{"gene":"PF3D7_1412100","run_date":"2026-09-08T19:44:17","timeline":{"discoveries":[{"year":2020,"finding":"MCMBP co-purified with the MCM complex (a replicative helicase required for genomic DNA replication), establishing its physical association with the MCM complex in P. falciparum blood stages.","method":"Co-purification / mass spectrometry","journal":"Cellular microbiology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — single co-purification experiment reported in one lab, confirmed by independent immunoprecipitation of PfMCM4-FLAG in a second study (PMID:40592953)","pmids":["33124706","40592953"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2020,"finding":"Conditional depletion of MCMBP disrupts nuclear morphology and parasite proliferation without causing a block in DNA replication, indicating MCMBP is required for normal karyokinesis but not for DNA replication per se.","method":"Conditional knockdown (inducible depletion) with immunofluorescence microscopy and proliferation assay","journal":"Cellular microbiology","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional knockdown with multiple orthogonal readouts (proliferation, IFA for nuclear morphology, DNA replication assay), replicated and extended in a second independent study (PMID:34835432)","pmids":["33124706","34835432"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2020,"finding":"MCMBP depletion promotes formation of mitotic spindle microtubules with extensions connecting more than one DNA focus and causes abnormal centrin distribution, indicating a role in coordinating mitotic spindle organization and centrosome function.","method":"Conditional knockdown with immunofluorescence microscopy (anti-tubulin and anti-centrin staining)","journal":"Cellular microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — single lab, two orthogonal staining approaches (tubulin and centrin), confirmed and refined by U-ExM in independent follow-up study (PMID:34835432)","pmids":["33124706","34835432"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2020,"finding":"MCMBP-deficient P. falciparum parasites complete cytokinesis and form aneuploid merozoites with variable cellular and nuclear sizes, demonstrating the absence of a robust checkpoint that prevents cytokinesis following aberrant karyokinesis.","method":"Conditional knockdown with flow cytometry and microscopy to assess merozoite nuclear content and size","journal":"Cellular microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — single lab, multiple readouts (nuclear size variability, DNA content, merozoite morphology)","pmids":["33124706"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2021,"finding":"Using ultrastructure expansion microscopy (U-ExM) with a novel nuclear envelope stain, MCMBP-deficient parasites display aberrant hemispindles and mitotic spindles approximately 30% longer with more branches, anaphase chromatin bridges, and individual nuclei containing multiple microtubule structures, refining the role of MCMBP in mitotic spindle integrity and chromosome segregation.","method":"Ultrastructure expansion microscopy (U-ExM) with nuclear envelope staining and anti-tubulin labeling following conditional knockdown","journal":"Microorganisms","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — single lab, novel high-resolution imaging method with multiple structural readouts; extends prior study","pmids":["34835432"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2025,"finding":"Proximity labeling (BirA-based) using MCMBP as bait identified an uncharacterized protein PfAnchor (Pf3D7_0613600) as a proximal neighbor, placing MCMBP in a spatial proximity network that includes apicoplast-associated proteins.","method":"Proximity labeling (BioID/TurboID) with mass spectrometry, using MCMBP-BirA-HA as bait","journal":"Nature communications","confidence":"Low","confidence_rationale":"Tier 3 / Weak — proximity labeling identifies spatial neighbors but does not establish direct physical interaction; single study, no reciprocal validation for MCMBP itself","pmids":["41309594"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":"3D7"}]},{"year":2025,"finding":"Immunoprecipitation of PfMCM4-FLAG significantly enriched MCMBP along with PfMCM2/3/5/6/7, confirming MCMBP is a stable component of the P. falciparum MCM replicative helicase complex in asexual blood stages; notably, MCM8 and MCM9 accessory proteins were absent from this complex.","method":"Immunoprecipitation of FLAG-tagged PfMCM4 followed by LC-MS/MS","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP with mass spectrometry in a single independent lab confirming prior co-purification result","pmids":["40592953"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2025,"finding":"Knockdown of PfRBX1 (a CRL E3 ligase component) leads to increased protein levels of MCMBP and all six MCM complex subunits (MCM2–7), suggesting that CRL ubiquitin ligase activity negatively regulates the abundance or stability of the MCM complex including MCMBP.","method":"Conditional knockdown of PfRBX1 with western blot assessment of MCMBP and MCM protein levels","journal":"Scientific reports","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, single method (western blot after knockdown of an upstream regulator); indirect evidence for CRL-mediated regulation of MCMBP stability","pmids":["40592953"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"current_model":"In P. falciparum, MCMBP (PF3D7_1412100) is a stable accessory subunit of the MCM replicative helicase complex (physically associated with MCM2–7 by co-purification and reciprocal co-IP) that is required for proper mitotic spindle organization and karyokinesis during schizogony: its conditional depletion causes aberrant hemispindles and mitotic spindles, anaphase chromatin bridges, and abnormal centrin distribution, leading to aneuploid merozoites, yet cytokinesis proceeds unimpeded, demonstrating the absence of a checkpoint coupling karyokinesis to cytokinesis; its abundance is negatively regulated by the CRL ubiquitin ligase pathway."},"narrative":{"mechanistic_narrative":"In Plasmodium falciparum, MCMBP (PF3D7_1412100) is a stable accessory subunit of the MCM replicative helicase complex, physically associating with the MCM2–7 subunits by co-purification and confirmed by reciprocal immunoprecipitation of PfMCM4-FLAG, which enriches MCMBP together with MCM2/3/5/6/7 [PMID:33124706, PMID:40592953]. Despite this association with the DNA replication machinery, MCMBP's essential role during schizogony is in nuclear division rather than DNA synthesis: conditional depletion disrupts nuclear morphology and parasite proliferation without blocking DNA replication [PMID:33124706, PMID:34835432]. Loss of MCMBP produces aberrant hemispindles and mitotic spindles (~30% longer with additional branches), anaphase chromatin bridges, individual nuclei bearing multiple microtubule structures, and abnormal centrin distribution, establishing a requirement for MCMBP in mitotic spindle integrity, centrosome function, and chromosome segregation [PMID:33124706, PMID:34835432]. Because MCMBP-deficient parasites nonetheless complete cytokinesis and form aneuploid merozoites of variable size, karyokinesis and cytokinesis are not coupled by a robust checkpoint in this organism [PMID:33124706]. The abundance of MCMBP and the MCM subunits is negatively regulated by CRL ubiquitin ligase activity, as knockdown of the CRL component PfRBX1 raises their protein levels [PMID:40592953].","teleology":[{"year":2020,"claim":"Whether PF3D7_1412100 associates with the replication machinery was unknown; co-purification placed it physically within the MCM replicative helicase complex, defining it as an MCM-associated protein in blood-stage parasites.","evidence":"Co-purification with mass spectrometry in P. falciparum blood stages","pmids":["33124706","40592953"],"confidence":"Medium","gaps":["Does not resolve whether the association is direct or which MCM subunit MCMBP contacts","Stoichiometry and structural arrangement within the complex not defined"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2020,"claim":"It was unclear whether MCMBP acts in DNA replication like the core helicase or in a distinct process; conditional depletion showed it is required for normal karyokinesis but dispensable for DNA replication, uncoupling its function from bulk genome synthesis.","evidence":"Inducible conditional knockdown with proliferation assay, IFA for nuclear morphology, and DNA replication readout in P. falciparum","pmids":["33124706","34835432"],"confidence":"High","gaps":["Molecular mechanism linking an MCM-associated protein to karyokinesis not defined","Whether the karyokinesis defect is a direct MCMBP function or a downstream consequence unresolved"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2020,"claim":"The nature of the nuclear defect was undefined; depletion was shown to disrupt mitotic spindle organization and centrin distribution, and to permit cytokinesis despite aberrant karyokinesis, revealing the absence of a karyokinesis-to-cytokinesis checkpoint and production of aneuploid merozoites.","evidence":"Conditional knockdown with anti-tubulin/anti-centrin IFA, flow cytometry, and microscopy of merozoite nuclear content in P. falciparum","pmids":["33124706"],"confidence":"Medium","gaps":["How MCMBP influences spindle and centrin behavior mechanistically not established","Single-lab observation for the checkpoint-absence and aneuploidy phenotype"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2021,"claim":"The spindle phenotype was described only at conventional resolution; ultrastructure expansion microscopy refined it, revealing aberrant hemispindles, elongated over-branched spindles, anaphase chromatin bridges, and nuclei with multiple microtubule structures, sharpening the segregation-defect picture.","evidence":"U-ExM with a novel nuclear envelope stain and anti-tubulin labeling following conditional knockdown in P. falciparum","pmids":["34835432"],"confidence":"Medium","gaps":["Does not establish whether the spindle defects originate from MCMBP's role at centrosomes, chromatin, or spindle microtubules directly","Single-lab imaging study"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2025,"claim":"Whether MCMBP resides only within the MCM complex or has a broader spatial neighborhood was untested; proximity labeling placed it near an uncharacterized protein PfAnchor and apicoplast-associated proteins, hinting at a wider spatial network.","evidence":"BirA-based proximity labeling with mass spectrometry using MCMBP-BirA-HA as bait in P. falciparum 3D7","pmids":["41309594"],"confidence":"Low","gaps":["Proximity labeling does not establish direct physical interaction","No reciprocal validation for MCMBP; functional significance of PfAnchor proximity unknown"],"attribution":[{"species":"Plasmodium falciparum","strain":"3D7"}]},{"year":2025,"claim":"The MCM-complex membership of MCMBP rested on one co-purification; reciprocal IP of PfMCM4-FLAG confirmed MCMBP as a stable co-purifying subunit alongside MCM2/3/5/6/7, while showing MCM8/MCM9 are not part of this complex.","evidence":"Immunoprecipitation of FLAG-tagged PfMCM4 followed by LC-MS/MS in P. falciparum asexual blood stages","pmids":["40592953"],"confidence":"Medium","gaps":["Does not map direct contacts or the position of MCMBP within the complex","Complex composition determined in asexual stages only"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2025,"claim":"How MCMBP/MCM abundance is controlled was unknown; knockdown of the CRL E3 component PfRBX1 raised levels of MCMBP and all six MCM subunits, implicating CRL ubiquitin ligase activity in negatively regulating their stability.","evidence":"Conditional knockdown of PfRBX1 with western blot quantification of MCMBP and MCM subunit levels in P. falciparum","pmids":["40592953"],"confidence":"Low","gaps":["Indirect evidence via an upstream regulator; direct ubiquitination of MCMBP not demonstrated","Single lab, single method (western blot after knockdown)"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":null,"claim":"The direct molecular mechanism by which an MCM-complex-associated protein controls mitotic spindle organization, centrosome/centrin behavior, and chromosome segregation during schizogony remains unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural model of MCMBP within the MCM complex","No defined biochemical activity of MCMBP toward spindle or centrosome components","Whether the CRL-mediated regulation is functionally coupled to the karyokinesis role unknown"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["MCM replicative helicase complex (MCM2–7 with MCMBP)"],"partners":["MCM COMPLEX (MCM2/3/4/5/6/7)","PFMCM4","PFANCHOR (PF3D7_0613600) — PROXIMITY NEIGHBOR","PFRBX1 (CRL E3 LIGASE COMPONENT) — NEGATIVE REGULATOR OF ABUNDANCE"],"other_free_text":["Required for normal karyokinesis during schizogony but not for bulk DNA replication [#1].","Depletion causes aberrant hemispindles/mitotic spindles, anaphase chromatin bridges, and abnormal centrin distribution [#2, #4].","Loss produces aneuploid merozoites while cytokinesis proceeds, indicating no karyokinesis-to-cytokinesis checkpoint [#3].","Abundance negatively regulated by CRL ubiquitin ligase activity (via PfRBX1) [#7].","MCM8 and MCM9 accessory proteins are absent from the MCMBP-containing MCM complex [#6]."]}},"prefetch_data":{},"corpus_meta":[{"pmid":"34835432","id":"PMC_34835432","title":"Expansion Microscopy Reveals Plasmodium falciparum Blood-Stage Parasites Undergo Anaphase with A Chromatin Bridge in the Absence of Mini-Chromosome Maintenance Complex Binding Protein.","date":"2021","source":"Microorganisms","url":"https://pubmed.ncbi.nlm.nih.gov/34835432","citation_count":72,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["MCMBP","mini-chromosome maintenance complex-binding protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"33124706","id":"PMC_33124706","title":"Depletion of the mini-chromosome maintenance complex binding protein allows the progression of cytokinesis despite abnormal karyokinesis during the asexual development of Plasmodium falciparum.","date":"2020","source":"Cellular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/33124706","citation_count":16,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["mini-chromosome maintenance complex-binding protein"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"41309594","id":"","title":"An essential adaptor for apicoplast fission and inheritance in malaria parasites.","date":"2025","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/41309594","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["MCMBP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"40592953","id":"","title":"Functional characterisation of components in two Plasmodium falciparum Cullin-RING-Ligase complexes.","date":"2025","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/40592953","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["MCMBP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"38987258","id":"","title":"Disruption of Plasmodium falciparum kinetochore proteins destabilises the nexus between the centrosome equivalent and the mitotic apparatus.","date":"2024","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/38987258","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["MCMBP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"36862652","id":"","title":"Plasmodium schizogony, a chronology of the parasite's cell cycle in the blood stage.","date":"2023","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/36862652","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["MCMBP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"39445823","id":"","title":"The Plasmodium falciparum histone methyltransferase SET10 participates in a chromatin modulation network crucial for intraerythrocytic development.","date":"2024","source":"mSphere","url":"https://pubmed.ncbi.nlm.nih.gov/39445823","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["MCMBP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"39777415","id":"","title":"Widespread release of translational repression across Plasmodium's host-to-vector transmission event.","date":"2025","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/39777415","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["MCMBP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"33912479","id":"","title":"The Modular Circuitry of Apicomplexan Cell Division Plasticity.","date":"2021","source":"Frontiers in cellular and infection microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/33912479","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["MCMBP"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":11035,"output_tokens":2096,"usd":0.032273,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":7410,"output_tokens":3248,"usd":0.059125,"stage2_stop_reason":"end_turn"},"total_usd":0.091398,"stage1_batch_id":"msgbatch_01SRp5hyRc82zNjddxyCCXGk","stage2_batch_id":"msgbatch_01K3BTmBazRo3pRrMvyaPMTY","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2020,\n      \"finding\": \"MCMBP co-purified with the MCM complex (a replicative helicase required for genomic DNA replication), establishing its physical association with the MCM complex in P. falciparum blood stages.\",\n      \"method\": \"Co-purification / mass spectrometry\",\n      \"journal\": \"Cellular microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — single co-purification experiment reported in one lab, confirmed by independent immunoprecipitation of PfMCM4-FLAG in a second study (PMID:40592953)\",\n      \"pmids\": [\"33124706\", \"40592953\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Conditional depletion of MCMBP disrupts nuclear morphology and parasite proliferation without causing a block in DNA replication, indicating MCMBP is required for normal karyokinesis but not for DNA replication per se.\",\n      \"method\": \"Conditional knockdown (inducible depletion) with immunofluorescence microscopy and proliferation assay\",\n      \"journal\": \"Cellular microbiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional knockdown with multiple orthogonal readouts (proliferation, IFA for nuclear morphology, DNA replication assay), replicated and extended in a second independent study (PMID:34835432)\",\n      \"pmids\": [\"33124706\", \"34835432\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"MCMBP depletion promotes formation of mitotic spindle microtubules with extensions connecting more than one DNA focus and causes abnormal centrin distribution, indicating a role in coordinating mitotic spindle organization and centrosome function.\",\n      \"method\": \"Conditional knockdown with immunofluorescence microscopy (anti-tubulin and anti-centrin staining)\",\n      \"journal\": \"Cellular microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — single lab, two orthogonal staining approaches (tubulin and centrin), confirmed and refined by U-ExM in independent follow-up study (PMID:34835432)\",\n      \"pmids\": [\"33124706\", \"34835432\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"MCMBP-deficient P. falciparum parasites complete cytokinesis and form aneuploid merozoites with variable cellular and nuclear sizes, demonstrating the absence of a robust checkpoint that prevents cytokinesis following aberrant karyokinesis.\",\n      \"method\": \"Conditional knockdown with flow cytometry and microscopy to assess merozoite nuclear content and size\",\n      \"journal\": \"Cellular microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — single lab, multiple readouts (nuclear size variability, DNA content, merozoite morphology)\",\n      \"pmids\": [\"33124706\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Using ultrastructure expansion microscopy (U-ExM) with a novel nuclear envelope stain, MCMBP-deficient parasites display aberrant hemispindles and mitotic spindles approximately 30% longer with more branches, anaphase chromatin bridges, and individual nuclei containing multiple microtubule structures, refining the role of MCMBP in mitotic spindle integrity and chromosome segregation.\",\n      \"method\": \"Ultrastructure expansion microscopy (U-ExM) with nuclear envelope staining and anti-tubulin labeling following conditional knockdown\",\n      \"journal\": \"Microorganisms\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — single lab, novel high-resolution imaging method with multiple structural readouts; extends prior study\",\n      \"pmids\": [\"34835432\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Proximity labeling (BirA-based) using MCMBP as bait identified an uncharacterized protein PfAnchor (Pf3D7_0613600) as a proximal neighbor, placing MCMBP in a spatial proximity network that includes apicoplast-associated proteins.\",\n      \"method\": \"Proximity labeling (BioID/TurboID) with mass spectrometry, using MCMBP-BirA-HA as bait\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — proximity labeling identifies spatial neighbors but does not establish direct physical interaction; single study, no reciprocal validation for MCMBP itself\",\n      \"pmids\": [\"41309594\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"3D7\"}]\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Immunoprecipitation of PfMCM4-FLAG significantly enriched MCMBP along with PfMCM2/3/5/6/7, confirming MCMBP is a stable component of the P. falciparum MCM replicative helicase complex in asexual blood stages; notably, MCM8 and MCM9 accessory proteins were absent from this complex.\",\n      \"method\": \"Immunoprecipitation of FLAG-tagged PfMCM4 followed by LC-MS/MS\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP with mass spectrometry in a single independent lab confirming prior co-purification result\",\n      \"pmids\": [\"40592953\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Knockdown of PfRBX1 (a CRL E3 ligase component) leads to increased protein levels of MCMBP and all six MCM complex subunits (MCM2–7), suggesting that CRL ubiquitin ligase activity negatively regulates the abundance or stability of the MCM complex including MCMBP.\",\n      \"method\": \"Conditional knockdown of PfRBX1 with western blot assessment of MCMBP and MCM protein levels\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, single method (western blot after knockdown of an upstream regulator); indirect evidence for CRL-mediated regulation of MCMBP stability\",\n      \"pmids\": [\"40592953\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"In P. falciparum, MCMBP (PF3D7_1412100) is a stable accessory subunit of the MCM replicative helicase complex (physically associated with MCM2–7 by co-purification and reciprocal co-IP) that is required for proper mitotic spindle organization and karyokinesis during schizogony: its conditional depletion causes aberrant hemispindles and mitotic spindles, anaphase chromatin bridges, and abnormal centrin distribution, leading to aneuploid merozoites, yet cytokinesis proceeds unimpeded, demonstrating the absence of a checkpoint coupling karyokinesis to cytokinesis; its abundance is negatively regulated by the CRL ubiquitin ligase pathway.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"In Plasmodium falciparum, MCMBP (PF3D7_1412100) is a stable accessory subunit of the MCM replicative helicase complex, physically associating with the MCM2–7 subunits by co-purification and confirmed by reciprocal immunoprecipitation of PfMCM4-FLAG, which enriches MCMBP together with MCM2/3/5/6/7 [#0, #6]. Despite this association with the DNA replication machinery, MCMBP's essential role during schizogony is in nuclear division rather than DNA synthesis: conditional depletion disrupts nuclear morphology and parasite proliferation without blocking DNA replication [#1]. Loss of MCMBP produces aberrant hemispindles and mitotic spindles (~30% longer with additional branches), anaphase chromatin bridges, individual nuclei bearing multiple microtubule structures, and abnormal centrin distribution, establishing a requirement for MCMBP in mitotic spindle integrity, centrosome function, and chromosome segregation [#2, #4]. Because MCMBP-deficient parasites nonetheless complete cytokinesis and form aneuploid merozoites of variable size, karyokinesis and cytokinesis are not coupled by a robust checkpoint in this organism [#3]. The abundance of MCMBP and the MCM subunits is negatively regulated by CRL ubiquitin ligase activity, as knockdown of the CRL component PfRBX1 raises their protein levels [#7].\",\n  \"teleology\": [\n    {\n      \"year\": 2020,\n      \"claim\": \"Whether PF3D7_1412100 associates with the replication machinery was unknown; co-purification placed it physically within the MCM replicative helicase complex, defining it as an MCM-associated protein in blood-stage parasites.\",\n      \"evidence\": \"Co-purification with mass spectrometry in P. falciparum blood stages\",\n      \"pmids\": [\"33124706\", \"40592953\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Does not resolve whether the association is direct or which MCM subunit MCMBP contacts\", \"Stoichiometry and structural arrangement within the complex not defined\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"It was unclear whether MCMBP acts in DNA replication like the core helicase or in a distinct process; conditional depletion showed it is required for normal karyokinesis but dispensable for DNA replication, uncoupling its function from bulk genome synthesis.\",\n      \"evidence\": \"Inducible conditional knockdown with proliferation assay, IFA for nuclear morphology, and DNA replication readout in P. falciparum\",\n      \"pmids\": [\"33124706\", \"34835432\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular mechanism linking an MCM-associated protein to karyokinesis not defined\", \"Whether the karyokinesis defect is a direct MCMBP function or a downstream consequence unresolved\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"The nature of the nuclear defect was undefined; depletion was shown to disrupt mitotic spindle organization and centrin distribution, and to permit cytokinesis despite aberrant karyokinesis, revealing the absence of a karyokinesis-to-cytokinesis checkpoint and production of aneuploid merozoites.\",\n      \"evidence\": \"Conditional knockdown with anti-tubulin/anti-centrin IFA, flow cytometry, and microscopy of merozoite nuclear content in P. falciparum\",\n      \"pmids\": [\"33124706\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How MCMBP influences spindle and centrin behavior mechanistically not established\", \"Single-lab observation for the checkpoint-absence and aneuploidy phenotype\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"The spindle phenotype was described only at conventional resolution; ultrastructure expansion microscopy refined it, revealing aberrant hemispindles, elongated over-branched spindles, anaphase chromatin bridges, and nuclei with multiple microtubule structures, sharpening the segregation-defect picture.\",\n      \"evidence\": \"U-ExM with a novel nuclear envelope stain and anti-tubulin labeling following conditional knockdown in P. falciparum\",\n      \"pmids\": [\"34835432\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Does not establish whether the spindle defects originate from MCMBP's role at centrosomes, chromatin, or spindle microtubules directly\", \"Single-lab imaging study\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Whether MCMBP resides only within the MCM complex or has a broader spatial neighborhood was untested; proximity labeling placed it near an uncharacterized protein PfAnchor and apicoplast-associated proteins, hinting at a wider spatial network.\",\n      \"evidence\": \"BirA-based proximity labeling with mass spectrometry using MCMBP-BirA-HA as bait in P. falciparum 3D7\",\n      \"pmids\": [\"41309594\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Proximity labeling does not establish direct physical interaction\", \"No reciprocal validation for MCMBP; functional significance of PfAnchor proximity unknown\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"3D7\"}]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"The MCM-complex membership of MCMBP rested on one co-purification; reciprocal IP of PfMCM4-FLAG confirmed MCMBP as a stable co-purifying subunit alongside MCM2/3/5/6/7, while showing MCM8/MCM9 are not part of this complex.\",\n      \"evidence\": \"Immunoprecipitation of FLAG-tagged PfMCM4 followed by LC-MS/MS in P. falciparum asexual blood stages\",\n      \"pmids\": [\"40592953\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Does not map direct contacts or the position of MCMBP within the complex\", \"Complex composition determined in asexual stages only\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"How MCMBP/MCM abundance is controlled was unknown; knockdown of the CRL E3 component PfRBX1 raised levels of MCMBP and all six MCM subunits, implicating CRL ubiquitin ligase activity in negatively regulating their stability.\",\n      \"evidence\": \"Conditional knockdown of PfRBX1 with western blot quantification of MCMBP and MCM subunit levels in P. falciparum\",\n      \"pmids\": [\"40592953\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Indirect evidence via an upstream regulator; direct ubiquitination of MCMBP not demonstrated\", \"Single lab, single method (western blot after knockdown)\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The direct molecular mechanism by which an MCM-complex-associated protein controls mitotic spindle organization, centrosome/centrin behavior, and chromosome segregation during schizogony remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structural model of MCMBP within the MCM complex\", \"No defined biochemical activity of MCMBP toward spindle or centrosome components\", \"Whether the CRL-mediated regulation is functionally coupled to the karyokinesis role unknown\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [],\n    \"localization\": [],\n    \"pathway\": [],\n    \"complexes\": [\"MCM replicative helicase complex (MCM2–7 with MCMBP)\"],\n    \"partners\": [\"MCM complex (MCM2/3/4/5/6/7)\", \"PfMCM4\", \"PfAnchor (Pf3D7_0613600) — proximity neighbor\", \"PfRBX1 (CRL E3 ligase component) — negative regulator of abundance\"],\n    \"other_free_text\": [\n      \"Required for normal karyokinesis during schizogony but not for bulk DNA replication [#1].\",\n      \"Depletion causes aberrant hemispindles/mitotic spindles, anaphase chromatin bridges, and abnormal centrin distribution [#2, #4].\",\n      \"Loss produces aneuploid merozoites while cytokinesis proceeds, indicating no karyokinesis-to-cytokinesis checkpoint [#3].\",\n      \"Abundance negatively regulated by CRL ubiquitin ligase activity (via PfRBX1) [#7].\",\n      \"MCM8 and MCM9 accessory proteins are absent from the MCMBP-containing MCM complex [#6].\"\n    ]\n  }\n}","audit_flag":null,"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_1412100","name":null,"product":"mini-chromosome maintenance complex-binding protein","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PbANKA","gene_id":"PBANKA_1030500","name":null,"product":"mini-chromosome maintenance complex-binding protein, putative","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_1346200","name":null,"product":"mini-chromosome maintenance complex-binding protein, putative","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"MCMBP","evaluation":null}