BDP1

BDP1 (PF3D7_1033700) is a nuclear bromodomain protein of Plasmodium falciparum that functions as an acetylation-reading chromatin regulator governing both activation of red blood cell invasion genes and silencing of variant surface antigen (VSA) virulence genes (PMID:26067602, PMID:35493110, PMID:23181666). Its bromodomain adopts the conserved bromodomain fold but employs a binding mechanism distinct from human bromodomain families, preferentially recognizing tetra-acetylated histone H4 with weaker binding to multi-acetylated H2A.Z and to acetylated histone H3 (PMID:36328269, PMID:26067602). Through this reader activity BDP1 is recruited to chromatin in an acetylation-dependent manner and occupies transcriptional start sites of invasion genes, where its conditional knockdown downregulates invasion gene expression and blocks parasite invasion while overexpression enhances the same genes (PMID:26067602, PMID:31728527). At these active regulatory sites BDP1 co-localizes with the ApiAP2 transcription factor PfAP2-I and with H3K18ac/H3K27ac marks in open chromatin, and it cooperates with PfAP2-I, the PfGCN5 acetyltransferase complex, and PfPRMT5 to activate invasion gene transcription (PMID:28618269, PMID:33225957, PMID:34403450, PMID:37349497). BDP1 assembles into a constitutive bromodomain-protein complex with PfBDP2 and PfBDP7; the BDP1/BDP7 module is co-enriched across the heterochromatic gene bodies of PfEMP1, RIFIN, STEVOR, and PfMC-2TM, and BDP1 knockdown de-represses these VSA families at mRNA and protein levels, establishing an additional role in heterochromatic silencing of virulence genes (PMID:26067602, PMID:35493110). The bromodomain is a validated small-molecule target, with inhibitor-bound co-crystal structures and knockdown-confirmed on-target activity in parasites (PMID:40099623).

1. 2012 Medium

   Before functional study, establishing where BDP1 resides was needed to constrain its possible roles; nuclear proteomics placed it in the nucleus, consistent with a chromatin-associated function.

   Evidence Mass spectrometry nuclear proteomics with transgenic localization validation

   PMID:23181666

   Open questions at the time

   • Does not address chromatin binding specificity or target genes
   • No functional readout
2. 2015 High

   The central question of what BDP1 does was answered by showing it binds chromatin at invasion-gene start sites and directly controls their expression, defining it as a regulator of red blood cell invasion.

   Evidence Conditional knockdown, overexpression, ChIP and transcriptional analysis in P. falciparum; Co-IP linking BDP1 to acetylated H3 and to PfBDP2

   PMID:26067602

   Open questions at the time

   • Precise acetyl-mark specificity not resolved biophysically
   • Mechanism of PfBDP2 partnership from a single Co-IP
3. 2017 Medium

   To connect BDP1 to sequence-specific targeting, it was shown to associate with the ApiAP2 factor PfAP2-I in a chromatin complex co-regulating invasion genes, explaining how a generic acetyl-reader reaches specific promoters.

   Evidence Co-immunoprecipitation and genome-wide ChIP-seq co-occupancy

   PMID:28618269

   Open questions at the time

   • Direct vs indirect nature of the interaction unresolved
   • Single-lab data
4. 2019 Medium

   Whether BDP1 recruitment is acetylation-driven was tested quantitatively, showing it is a reader preferentially pulled down by acetylated histone peptides and forming a BDP1/BDP2 core complex.

   Evidence Quantitative histone peptide pull-downs and interaction proteomics

   PMID:31728527

   Open questions at the time

   • Which specific acetyl marks dominate recruitment not fully defined
   • Single lab
5. 2020 Medium

   Refining the activation model, BDP1 was shown to co-localize with PfAP2-I and active marks H3K18ac/H3K27ac at positioned nucleosomes in open chromatin, marking active regulatory sequences.

   Evidence Integrated ChIP-seq of BDP1, PfAP2-I and histone marks plus promoter assays

   PMID:33225957

   Open questions at the time

   • BDP1 tracks were re-analyzed prior datasets, not newly generated
   • Causality of mark vs binding not established
6. 2021 Medium

   The pathway logic of activation was extended by epistasis showing BDP1-regulated genes overlap with PfGCN5-complex and PfAP2-I targets, implicating BDP1 in recruiting the GCN5 acetyltransferase complex to invasion promoters.

   Evidence Genetic domain deletions, transcriptomics and overlap/epistasis analysis

   PMID:34403450

   Open questions at the time

   • BDP1's role inferred from overlap, not direct BDP1 manipulation in this study
   • Recruitment mechanism not shown directly
7. 2022 High

   Two advances refined the mechanism: the bromodomain crystal structure defined its unique acetyl-lysine binding specificity, and Co-IP/ChIP-seq revealed a BDP1/BDP7 complex controlling heterochromatic VSA silencing, uncovering a repressive role in addition to activation.

   Evidence X-ray crystallography, NMR and ITC for binding specificity; Co-IP, ChIP-seq and conditional knockdown with mRNA/protein readouts for VSA de-repression

   PMID:35493110 PMID:36328269

   Open questions at the time

   • How one reader partitions between activating and repressive contexts unresolved
   • Structural basis for VSA gene-body enrichment unknown
8. 2023 Low

   To further map its regulatory network, BDP1 was found in the interactome of the arginine methyltransferase PfPRMT5, placing it among invasion-related regulators alongside AP2-I and GCN5.

   Evidence Co-immunoprecipitation interactome proteomics

   PMID:37349497

   Open questions at the time

   • Single Co-IP interactome; BDP1 not directly manipulated
   • Functional consequence of the PRMT5 association untested
9. 2025 High

   Establishing BDP1 as a druggable target, inhibitor-bound co-crystal structures were solved and knockdown-verified on-target parasite sensitivity, with the P. vivax ortholog bromodomain also structurally characterized.

   Evidence Co-crystal X-ray structures, ITC, docking and conditional knockdown in P. falciparum; structural characterization of PvBDP1-BRD

   PMID:40099623

   Open questions at the time

   • In vivo antimalarial efficacy not addressed
   • Selectivity over other parasite bromodomains not fully defined

• How BDP1 mechanistically switches between activating invasion genes and repressing heterochromatic VSA families through the same acetyl-reading domain remains unresolved.
• No mechanism explaining dual activator/repressor behavior
• Contribution of BDP2 vs BDP7 partners to context choice unknown
• Whether distinct acetyl marks dictate each mode untested