CAF1A

PF3D7_0501800 (CAF1A) is a Plasmodium falciparum chromatin assembly factor 1 subunit that acts as a histone chaperone in nucleosome assembly and heterochromatin maintenance (PMID:29183721). It physically associates with PfCAF2 and histones and co-localizes with the heterochromatin protein PfHP1 at telomeric repeat regions and at central and subtelomeric var gene loci, consistent with a role in maintaining silenced chromatin at these loci (PMID:29183721). CAF1A is also embedded in broader chromatin-regulatory networks in blood-stage parasites, having been captured as a proximity interactor of the histone methyltransferase PfSET10 (PMID:39445823) and as a co-purifying partner of the gametocyte transcription factor AP2-G2 within a SAGA-like effector complex linked to the H3K18acK23ac histone code (PMID:35051657). Beyond these interaction and localization data, the enzymatic and mechanistic details of CAF1A's chaperone activity have not been characterized in the available corpus, and its associations with PfSET10 and AP2-G2 rest on single proximity/proteomics experiments without reciprocal validation.

1. 2017 Medium

   Establishing whether CAF1A operates in heterochromatin biology required identifying its physical partners and genomic occupancy; co-IP and ChIP placed it with PfCAF2, histones, and PfHP1 at telomeric and var loci, defining it as a histone chaperone for nucleosome assembly and heterochromatin maintenance.

   Evidence Co-immunoprecipitation and ChIP at telomeric and var gene loci in P. falciparum

   PMID:29183721

   Open questions at the time

   • No in vitro reconstitution of chaperone or nucleosome-assembly activity
   • No mutagenesis to define which interactions are direct versus complex-mediated
   • Functional consequence of CAF1A loss on var gene silencing not tested
2. 2017 Low

   To test a role in genome maintenance, CAF1A protein levels were monitored after genotoxic stress; upregulation following MMS and HU treatment implicated it in the DNA damage repair response.

   Evidence Western blot / expression analysis after MMS and HU treatment in P. falciparum

   PMID:29183721

   Open questions at the time

   • Single method (expression change) without functional rescue or pathway placement
   • Does not identify which repair pathway CAF1A participates in
   • No demonstration that upregulation is required for survival under stress
3. 2022 Low

   Whether CAF1A contributes to sexual-stage gene regulation was addressed by chromatin proteomics of AP2-G2, which co-purified CAF1A within a gametocyte-specific SAGA-like effector complex associated with H3K18acK23ac.

   Evidence Chromatin proteomics / co-purification mass spectrometry in P. falciparum

   PMID:35051657

   Open questions at the time

   • Single co-purification experiment without reciprocal validation specific to CAF1A
   • Direct versus indirect association with AP2-G2 unresolved
   • No functional role of CAF1A in gametocyte gene regulation demonstrated
4. 2024 Low

   Proximity labeling of the histone methyltransferase PfSET10 identified CAF1A as a network member, extending its associations into blood-stage chromatin-remodeling machinery.

   Evidence TurboID proximity-labeling coupled with mass spectrometry in blood-stage P. falciparum

   PMID:39445823

   Open questions at the time

   • Single proximity-labeling experiment with no reciprocal validation or functional follow-up for CAF1A
   • Proximity does not establish a direct or stable interaction
   • Functional consequence of the CAF1A–PfSET10 association untested

• The intrinsic biochemical activity of CAF1A as a histone chaperone and its causal requirement for nucleosome assembly, var gene silencing, DNA repair, and gametocyte gene regulation remain undefined.
• No in vitro histone-chaperone assay
• No loss-of-function phenotype for CAF1A
• Direction of interactions (direct vs complex-mediated) with PfHP1, PfSET10, and AP2-G2 not resolved