BDP7

BDP7 (PF3D7_1124300) is a nuclear bromodomain-containing protein of Plasmodium falciparum that functions in heterochromatin-mediated silencing of clonally variant virulence gene families (PMID:35493110, PMID:23181666). It is a constitutive component of the PfBDP1/BDP2 core chromatin complex, physically associating with PfBDP1, and shares genome-wide chromatin occupancy with PfBDP1 both at invasion gene promoters in mature schizonts and across the gene bodies of variant surface antigen (VSA) families within heterochromatin in early schizonts (PMID:35493110). Conditional depletion of BDP7 de-represses the PfEMP1, RIFIN, STEVOR, and PfMC-2TM VSA families at the mRNA and protein levels, establishing a direct role in maintaining their silencing (PMID:35493110). Partial depletion does not detectably impair parasite viability under standard culture, indicating BDP7 is not individually essential at the depletion levels achieved (PMID:35493110). Beyond its complex membership, chromatin association, and silencing phenotype, no further mechanistic detail—such as the histone modifications recognized by its predicted bromodomain—has been characterized in the available corpus.

1. 2012 Medium

   Before any functional annotation, establishing where BDP7 resides in the cell was the first step toward its role; this showed BDP7 is a nuclear protein, consistent with a chromatin-associated function.

   Evidence Nuclear fractionation and mass spectrometry of the P. falciparum nuclear proteome, validated by transgenic GFP-tagged fluorescence microscopy

   PMID:23181666

   Open questions at the time

   • No functional or mechanistic role assigned in this study
   • No interaction partners or chromatin targets identified
   • Proteome-wide survey with limited gene-specific depth
2. 2022 High

   The open question of whether BDP7 acts alone or within a complex was resolved by showing it constitutively associates with PfBDP1/BDP2 and co-occupies invasion gene promoters, placing BDP7 in a defined core chromatin regulatory complex.

   Evidence Co-immunoprecipitation and ChIP-seq in mature schizont-stage parasites, with bromodomain fold predicted by structural modelling

   PMID:35493110

   Open questions at the time

   • Bromodomain ligand/histone mark recognized by BDP7 not experimentally determined
   • Stoichiometry and architecture of the BDP1/BDP2/BDP7 complex unresolved
   • Direct DNA/chromatin binding by BDP7 versus recruitment via PfBDP1 not distinguished
3. 2022 Medium

   Whether BDP7 has a causal role in gene regulation was tested by depletion, showing it is required to keep the VSA virulence gene families silenced at both transcript and protein levels.

   Evidence DiCre-based conditional knockdown with RT-qPCR and Western blot/flow cytometry readouts of PfEMP1, RIFIN, STEVOR, and PfMC-2TM

   PMID:35493110

   Open questions at the time

   • Whether BDP7 silencing acts through the bromodomain or another domain is untested
   • Direct versus indirect contribution to each VSA family not dissected
   • Single lab; partial depletion may underestimate effects
4. 2022 Medium

   Mapping where BDP7 acts on the genome tied its silencing role to a physical location, showing co-enrichment with PfBDP1 in heterochromatin across VSA gene bodies in early schizonts.

   Evidence ChIP-seq chromatin occupancy mapping

   PMID:35493110

   Open questions at the time

   • Histone modification landscape underlying BDP7 recruitment not defined
   • Temporal dynamics of occupancy across the cell cycle not fully resolved
5. 2022 Medium

   The question of essentiality was addressed, showing partial BDP7 depletion does not detectably affect viability, indicating BDP7 is not individually essential at the depletion achieved.

   Evidence DiCre-based conditional knockdown with growth assay

   PMID:35493110

   Open questions at the time

   • Negative result limited by incomplete depletion
   • Possible essentiality under stress or in specific life-cycle stages untested
   • Redundancy with other complex members not evaluated

• It remains unknown what chromatin mark BDP7's predicted bromodomain recognizes and whether that recognition is mechanistically required for its role in complex assembly, heterochromatin targeting, and VSA silencing.
• No experimental demonstration of a histone-mark ligand for the BDP7 bromodomain
• No structure of BDP7 or the intact BDP1/BDP2/BDP7 complex
• Separation-of-function mutants distinguishing binding from silencing not reported