Affinage · Plasmodium

PF3D7_0903700

alpha tubulin 1

Annotated
2026-09-08
30 papers in source corpus 12 papers cited in narrative 12 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

Alpha-tubulin I (PF3D7_0903700) is a core structural component of the Plasmodium microtubule cytoskeleton, encoded by a two-intron gene on chromosome 9 and expressed in a stage-specific manner distinct from alpha-tubulin II, with protein accumulation peaking in schizonts and segmenters and evidence of assembly into spindle-pole and post-mitotic microtubular structures (PMID:2693901, PMID:2090947, PMID:17977543). Its expression level is rate-limiting for cytoskeletal architecture: in P. berghei, deleting or replacing the orthologous alpha-tubulin gene showed that tubulin abundance directly sets the number of subpellicular microtubules in sporozoites, with fewer/shorter microtubules crippling sporozoite formation, motility, and infectivity (a threshold of ~10 microtubules for infectivity), while chromosome segregation in oocysts proceeded even without microtubules (PMID:31368598). The protein carries several post-translational modifications — a C-terminal tyrosine epitope and MTOC-localized polyglutamylation (PMID:8488059, PMID:17977543), and O-GlcNAcylation in late trophozoites (PMID:29187233) — but K40 acetylation is not a feature of this protein: blood-stage alpha-tubulin I is unacetylated at K40, and in P. berghei a Q40K knock-in permitting acetylation had no phenotypic consequence, indicating this modification is dispensable (PMID:8488059, PMID:41531934). Alpha-tubulin I engages multiple partners: a lysine-rich C-terminal peptide competitively inhibits P. falciparum aldolase, consistent with a cytoskeletal scaffold for glycolytic enzymes (PMID:8459825); it is bound by apicortin and by Prefoldin subunits as a chaperone substrate, both interactions being druggable growth-dependencies (PMID:33633135, PMID:38925325); and it is displayed on the apical surface of live ookinetes where it binds the mosquito midgut protein FREP1 to orient midgut invasion, with anti-alpha-tubulin I antibodies reducing oocyst burden (PMID:37009496). It is also the target of antimitotic dinitroaniline and phosphorothioamidate herbicides, which bind at a site that has resisted structural definition by mutagenesis (PMID:23523992).

Mechanistic history

Synthesis pass · year-by-year structured walk · 12 steps
  1. 1989 Medium

    Establishing the gene's sequence and structure was the necessary first step to define alpha-tubulin I as a discrete tubulin gene rather than an undifferentiated tubulin activity.

    Evidence Genomic library screening and DNA sequencing of P. falciparum clones

    PMID:2693901

    Open questions at the time
    • No functional or expression data at this stage
    • Protein product not directly characterized
  2. 1990 Medium

    Chromosomal mapping distinguished alpha-tubulin I from alpha-tubulin II and beta-tubulin and showed stage-specific expression, establishing it as an independently regulated gene.

    Evidence Pulsed-field gel electrophoresis, chromosomal mapping and Northern blotting

    PMID:2090947

    Open questions at the time
    • Functional distinction between alpha-tubulin I and II not tested
    • Regulatory basis of stage specificity unknown
  3. 1993 Medium

    Defining the PTM status resolved which conserved tubulin modifications apply to this parasite protein, showing K40 is not acetylated in blood stages while the C-terminal tyrosine epitope is retained.

    Evidence PTM-specific antibody immunofluorescence and in vitro acetylation assay

    PMID:8488059

    Open questions at the time
    • Functional consequence of missing K40 acetylation not tested
    • Antibody-based, no site-resolved mass spectrometry
  4. 1993 Medium

    A lysine-rich alpha-tubulin peptide inhibiting aldolase implicated the cytoskeleton as an organizing matrix for glycolytic enzymes, extending tubulin's role beyond structure.

    Evidence In vitro enzyme inhibition with synthetic peptide plus site-directed mutagenesis of aldolase

    PMID:8459825

    Open questions at the time
    • Only a peptide fragment, not full-length alpha-tubulin I, was tested
    • In vivo relevance of the interaction not demonstrated
  5. 2007 Medium

    Mapping protein abundance across stages and detecting polyglutamylation at MTOCs linked alpha-tubulin I to spindle-pole/merozoite biogenesis and pinpointed its peak in schizonts.

    Evidence Isotype- and glutamylation-specific antibody Western blotting and immunofluorescence with stage fractionation

    PMID:17977543

    Open questions at the time
    • Enzymes mediating polyglutamylation not identified
    • Functional requirement of the modification not tested
  6. 2013 High

    Confirming direct herbicide binding to recombinant alpha-tubulin I identified it as the antimitotic drug target, but mutagenesis failed to localize the binding site.

    Evidence Recombinant expression, site-directed mutagenesis, fluorescence-quenching binding assay and liver-stage inhibition

    PMID:23523992

    Open questions at the time
    • Structural location of the herbicide site remains unresolved
    • Six designed mutations did not alter binding, so the true contact residues are unknown
  7. 2017 Medium

    Detecting O-GlcNAcylation added another PTM to the alpha-tubulin repertoire in late trophozoites, though assignment to isoform I versus II was not fully resolved.

    Evidence Click-chemistry enrichment with nano-LC MS/MS and antibody confirmation

    PMID:29187233

    Open questions at the time
    • Cannot unambiguously assign to alpha-tubulin I versus II
    • Functional role of O-GlcNAcylation not tested
  8. 2019 High

    Genetic titration of tubulin in P. berghei established that alpha-tubulin expression level quantitatively sets microtubule number and thereby sporozoite morphology, motility, and infectivity, defining a mechanistic threshold.

    Evidence Gene deletion/replacement, quantitative EM, motility/infectivity assays and mathematical modelling in P. berghei

    PMID:31368598

    Open questions at the time
    • Shown in P. berghei ortholog, not directly in PF3D7_0903700
    • Mechanism coupling tubulin level to microtubule count not molecularly dissected
  9. 2021 Low

    Identifying apicortin as a binding partner and showing tamoxifen-mediated disruption impairs growth suggested this interaction supports blood-stage progression.

    Evidence In silico modelling, in vitro pulldown and tamoxifen growth-inhibition assay

    PMID:33633135

    Open questions at the time
    • No reciprocal Co-IP or structural validation described
    • Tamoxifen effect may not be specific to the alpha-tubulin I–apicortin interaction
  10. 2023 Medium

    Demonstrating surface accessibility on ookinetes and FREP1 binding revealed a moonlighting adhesion role for alpha-tubulin I in mosquito midgut invasion and defined it as a transmission-blocking target.

    Evidence Live-cell IFA, ELISA, pull-down with FREP1 and antibody-based membrane feeding assays

    PMID:37009496

    Open questions at the time
    • Mechanism by which cytoskeletal tubulin reaches the ookinete surface unclear
    • Structural basis of the FREP1 interaction not defined
  11. 2024 Medium

    Identifying Prefoldin subunits as interactors positioned alpha-tubulin I as a chaperone substrate and revealed Biperiden as a growth-inhibitory drug acting on this axis across resistant strains.

    Evidence Co-IP MS/MS, biophysical interaction analysis and growth/ring-survival assays

    PMID:38925325

    Open questions at the time
    • Direct effect of Biperiden on the interaction versus off-target not fully separated
    • Consequence of Prefoldin loss for tubulin folding in vivo not shown
  12. 2025 Medium

    A Q40K knock-in in P. berghei testing whether restoring the acetylatable lysine matters showed K40 acetylation capacity is dispensable, confirming this modification is not required for microtubule function.

    Evidence Q40K site-directed mutagenesis and life-cycle phenotyping in P. berghei

    PMID:41531934

    Open questions at the time
    • Shown in P. berghei ortholog, not directly in PF3D7_0903700
    • Does not address whether other K40-linked functions exist

Open questions

Synthesis pass · forward-looking unresolved questions
  • The structural location of the antimitotic herbicide binding site and the molecular basis for how a cytoskeletal tubulin becomes surface-exposed to bind FREP1 remain unresolved.
  • No structure of alpha-tubulin I with bound herbicide
  • No mechanism explaining ookinete surface display of tubulin
  • Direct requirement of PF3D7_0903700 itself (versus P. berghei ortholog) for microtubule count not genetically shown in P. falciparum

Mechanism profile

Synthesis pass · controlled-vocabulary classification
Partners
APICORTIN [#8]MOSQUITO MIDGUT FREP1 [#9]PFALDOLASE (VIA LYSINE-RICH C-TERMINAL PEPTIDE) [#3]PREFOLDIN SUBUNITS PFD1-6 [#10]
Complex memberships
Prefoldin complex (as substrate, PFD1-6) [#10]

Evidence

Reading pass · 12 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1989 Alpha-tubulin I (PF3D7_0903700) of P. falciparum was isolated and sequenced from genomic clones; the gene contains two introns and encodes a 453 amino acid, ~50.3 kDa protein with high homology to other alpha-tubulins (94% identity to Toxoplasma gondii alpha-tubulin); intron positions are identical to those of T. gondii alpha-tubulin I. Genomic library screening, DNA sequencing, Southern blotting Molecular microbiology Medium 2693901
1990 Alpha-tubulin I (PF3D7_0903700) is located on chromosome 9 of P. falciparum, as determined by pulsed-field gel electrophoresis, and is expressed in a stage-specific manner distinct from alpha-tubulin II (chromosome 4) and beta-tubulin (chromosome 10). Pulsed-field gel electrophoresis, chromosomal mapping, Northern blotting Molecular and biochemical parasitology Medium 2090947
1993 In erythrocytic P. falciparum, the C-terminal tyrosine-containing epitope of alpha-tubulin I (PF3D7_0903700) is present and recognized by antibodies specific for that post-translational modification, similar to other organisms. However, Lysine-40 of alpha-tubulin I is NOT acetylated in blood stages examined, although the epitope it contributes to is conformationally conserved (recognizable after in vitro acetylation), despite lack of primary sequence homology immediately downstream of K40. Immunofluorescence microscopy with PTM-specific antibodies; in vitro acetylation assay followed by antibody recognition Parasitology Medium 8488059
1993 A peptide derived from P. falciparum alpha-tubulin (alpha-tubulin I, PF3D7_0903700) acts as a selective competitive inhibitor of P. falciparum aldolase (PfAldo) in vitro; the inhibitory activity depends on the presence of tandem lysine residues and the fine structure of the peptide, supporting a matrix organisation of glycolytic enzymes in the parasite. In vitro enzyme inhibition assay using synthetic peptide; site-directed mutagenesis of PfAldo Molecular and biochemical parasitology Medium 8459825
2007 Alpha-tubulin I (PF3D7_0903700) protein is produced in both asexual and sexual blood-stage P. falciparum parasites, with production reaching maximum levels in schizonts and segmenters. Evidence of post-translational polyglutamylation of P. falciparum tubulin (including alpha-tubulin I) was found, localised specifically to microtubule-organising centres and post-mitotic microtubular structures, suggesting roles in spindle pole body formation and merozoite biogenesis. Western blotting with isotype-specific antibodies; immunofluorescence with glutamylation-specific antibodies; stage-specific protein fractionation International journal for parasitology Medium 17977543
2013 Antimitotic herbicides (dinitroanilines, phosphorothioamidates) bind to P. falciparum alpha-tubulin I (PF3D7_0903700) at an unidentified site distinct from three previously proposed overlapping sites; site-directed mutagenesis introducing six amino acid changes designed to occlude the proposed herbicide-binding sites on recombinant alpha-tubulin I had little to no effect on herbicide binding affinity (Kd changes ≤1.6-fold). These herbicides also block liver-stage parasite development. Site-directed mutagenesis of alpha-tubulin I; recombinant protein expression in E. coli; fluorescence quenching binding assay; liver-stage parasite inhibition assay Molecular and biochemical parasitology High 23523992
2017 Alpha-tubulin (including alpha-tubulin I, PF3D7_0903700) of P. falciparum is O-GlcNAcylated in late trophozoites, as identified by proteomics; this was confirmed by probing click-chemistry-enriched O-GlcNAcylated proteins with an anti-alpha-tubulin antibody. Click chemistry labelling followed by mass spectrometry (nano-LC MS/MS); antibody confirmation of O-GlcNAcylated alpha-tubulin Malaria journal Medium 29187233
2019 In P. berghei, gene deletion and replacement targeting one of the two alpha-tubulin genes (alpha-tubulin I, the ortholog of PF3D7_0903700) showed that alpha-tubulin expression levels directly determine the number of subpellicular microtubules in sporozoites. Fewer and shorter microtubules severely impaired sporozoite formation, motility, and infectivity; infectious sporozoites required at least 10 microtubules. Chromosome segregation in oocysts proceeded even in the absence of microtubules. Gene deletion and replacement strategy; quantitative electron microscopy of microtubule number/length; sporozoite motility and infectivity assays; mathematical modelling The EMBO journal High 31368598
2021 P. falciparum apicortin interacts with alpha-tubulin I (PF3D7_0903700) in vitro; disruption of this interaction using tamoxifen (a p25-domain binding drug) inhibited parasite blood stage growth and progression. In silico modelling; in vitro interaction assay (pulldown); growth inhibition assay with tamoxifen Scientific reports Low 33633135
2023 P. falciparum alpha-tubulin I (PF3D7_0903700) is accessible on the surface of the apical complex of live ookinetes, and interacts with the mosquito midgut protein FREP1 (fibrinogen-related protein 1), as demonstrated by ELISA and pull-down assay. Polyclonal and monoclonal antibodies against recombinant alpha-tubulin I significantly reduced P. falciparum oocyst numbers in Anopheles gambiae midguts. The interaction between FREP1 and alpha-tubulin I is proposed to anchor and orient the ookinete invasive apparatus toward the midgut epithelium. Immunofluorescence assay on live ookinetes; ELISA; pull-down assay with insect cell-expressed FREP1; standard membrane feeding assay with polyclonal and monoclonal antibodies Frontiers in cellular and infection microbiology Medium 37009496
2024 P. falciparum Prefoldin subunits (PFD1-6) interact with alpha-tubulin I (PF3D7_0903700) as a substrate, as identified by immunoprecipitation coupled to MS/MS analysis. An FDA-approved drug Biperiden inhibits the Prefoldin complex interaction with alpha-tubulin I and inhibits parasite growth in both ART-sensitive and ART-resistant strains. Immunoprecipitation coupled MS/MS; biophysical interaction analysis; growth inhibition assay; ring survival assay The Journal of biological chemistry Medium 38925325
2025 In P. berghei, introduction of a Q40K mutation in alpha-tubulin I (ortholog of PF3D7_0903700, which naturally has Q40 instead of K40) did not affect parasite development or infectivity, indicating that the absence of K40 acetylation (which would require the lysine) is not detrimental to microtubule function in this species. Site-directed mutagenesis (Q40K knock-in); parasite phenotypic characterization across life cycle stages Microbial cell (Graz, Austria) Medium 41531934

Source papers

Stage 0 corpus · 30 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2014 A flow cytometry-based quantitative drug sensitivity assay for all Plasmodium falciparum gametocyte stages. PloS one 102 24736563
1993 Microtubular organization visualized by immunofluorescence microscopy during erythrocytic schizogony in Plasmodium falciparum and investigation of post-translational modifications of parasite tubulin. Parasitology 98 8488059
2000 Commitment to the production of male and female gametocytes in the human malaria parasite Plasmodium falciparum. Parasitology 90 11128797
1992 Alpha-tubulin II is a male-specific protein in Plasmodium falciparum. Molecular and biochemical parasitology 87 1484548
2008 Centrins, cell cycle regulation proteins in human malaria parasite Plasmodium falciparum. The Journal of biological chemistry 67 18693242
2010 An essential Aurora-related kinase transiently associates with spindle pole bodies during Plasmodium falciparum erythrocytic schizogony. Molecular microbiology 65 21166904
2012 Comparative gene expression profiling of P. falciparum malaria parasites exposed to three different histone deacetylase inhibitors. PloS one 59 22384084
1996 A developmental defect in Plasmodium falciparum male gametogenesis. The Journal of cell biology 49 8858179
2019 Microtubule number and length determine cellular shape and function in Plasmodium. The EMBO journal 48 31368598
1990 The tubulin genes of the human malaria parasite Plasmodium falciparum, their chromosomal location and sequence analysis of the alpha-tubulin II gene. Molecular and biochemical parasitology 45 2090947
1989 Isolation of alpha-tubulin genes from the human malaria parasite, Plasmodium falciparum: sequence analysis of alpha-tubulin. Molecular microbiology 42 2693901
2021 In Vitro Evaluation of the Potential Pharmacological Activity and Molecular Targets of New Benzimidazole-Based Schiff Base Metal Complexes. Antibiotics (Basel, Switzerland) 28 34208759
2010 Promiscuous expression of α-tubulin II in maturing male and female Plasmodium falciparum gametocytes. PloS one 28 21209927
2007 Isotype expression, post-translational modification and stage-dependent production of tubulins in erythrocytic Plasmodium falciparum. International journal for parasitology 26 17977543
2005 Plasmodium berghei alpha-tubulin II: a role in both male gamete formation and asexual blood stages. Molecular and biochemical parasitology 26 16115694
2017 Identification of O-GlcNAcylated proteins in Plasmodium falciparum. Malaria journal 24 29187233
1990 Isolation of alpha- and beta-tubulin genes of Plasmodium falciparum using a single oligonucleotide probe. Molecular and biochemical parasitology 21 2181306
2021 Interaction of Plasmodium falciparum apicortin with α- and β-tubulin is critical for parasite growth and survival. Scientific reports 20 33633135
2014 The development of loop-mediated isothermal amplification targeting alpha-tubulin DNA for the rapid detection of Plasmodium vivax. Malaria journal 19 24981710
2013 Antimitotic herbicides bind to an unidentified site on malarial parasite tubulin and block development of liver-stage Plasmodium parasites. Molecular and biochemical parasitology 19 23523992
2020 Plasmodium berghei Kinesin-5 Associates With the Spindle Apparatus During Cell Division and Is Important for Efficient Production of Infectious Sporozoites. Frontiers in cellular and infection microbiology 18 33154955
1988 Molecular clones of alpha-tubulin genes of Plasmodium yoelii reveal an unusual feature of the carboxy terminus. Molecular and biochemical parasitology 16 2459618
2018 Specific Targeting of Plant and Apicomplexa Parasite Tubulin through Differential Screening Using In Silico and Assay-Based Approaches. International journal of molecular sciences 14 30304836
2023 Targeting plasmodium α-tubulin-1 to block malaria transmission to mosquitoes. Frontiers in cellular and infection microbiology 13 37009496
1993 Selective inhibition of Plasmodium falciparum aldolase by a tubulin derived peptide and identification of the binding site. Molecular and biochemical parasitology 12 8459825
2016 In Silico Designing and Analysis of Inhibitors against Target Protein Identified through Host-Pathogen Protein Interactions in Malaria. International journal of medicinal chemistry 6 27057354
2024 Multicomponent syntheses enable the discovery of novel quisinostat-derived chemotypes as histone deacetylase inhibitors. European journal of medicinal chemistry 4 39549507
2025 Luminal acetylation of microtubules is not essential for Plasmodium berghei and Toxoplasma gondii survival. Microbial cell (Graz, Austria) 1 41531934
2024 Prefoldins are novel regulators of the unfolded protein response in artemisinin resistant Plasmodium falciparum malaria. The Journal of biological chemistry 1 38925325
2019 Investigation of the reactivity indices for the formation of substituted dinitroanilines and correlations to their dockings on α-tubulin of Plasmodium falciparum. Journal of molecular modeling 1 31713698