| Category | Specific claim | Evidence (short) | Key source (with year, venue) | URL | Citation ID(s) |
|---|---|---|---|---|---|
| Molecular function | Asf1 is the budding-yeast ASF1-family histone chaperone that binds H3–H4 dimers and shields the H3 tetramerization surface. | Conserved chaperone activity; binds H3–H4 and prevents inappropriate tetramer formation before handoff. | Ding et al., 2025, *Nucleic Acids Research* | https://doi.org/10.1093/nar/gkaf036 | (pqac-00000006) |
| Molecular function | The N-terminal core of ASF1 contains conserved acidic patches contacting histone H3 and also binds H4. | Review excerpt notes N-terminal 155 aa globular core; binds H3–H4 in vitro and in vivo and can bind each histone individually. | Breuer et al., 2024, *mBio* | https://doi.org/10.1128/mbio.02896-23 | (pqac-00000002) |
| Biological process | Asf1 functions in replication-coupled chromatin assembly and chromatin remodeling during transcription. | Hiraga excerpt states Asf1 assembles H3–H4 into nucleosomes and functions in DNA replication and transcription-coupled remodeling. | Hiraga et al., 2008, *Journal of Cell Biology* | https://doi.org/10.1083/jcb.200806065 | (pqac-00000012) |
| Pathway/module | Canonical budding-yeast handoff model: Asf1 binds newly synthesized H3–H4, presents them to Rtt109 for H3K56 acetylation, then acetylated dimers are transferred to CAF-1 and/or Rtt106 for deposition. | Dannah states H3K56ac is solely reliant on Asf1 and Asf1 stimulates Rtt109; Kattar-Mell states Asf1-bound cytoplasmic H3–H4 dimers are imported, acetylated by Rtt109, then transferred to downstream chaperones including CAF-1. | Dannah, 2024, thesis; Kattar-Mell, 2012, thesis | https://doi.org/10.32920/25233562.v1 | (pqac-00000010, pqac-00000015) |
| Key interactions | Asf1 functionally cooperates with the HIR complex and Rtt106 in replication-independent H3–H4 deposition and promoter fidelity. | Kim 2024 excerpt states Asf1 works with HIR and Rtt106 for replication-independent deposition and promoter fidelity; linked to heterochromatic silencing. | Kim et al., 2024, *Molecular Cell* | https://doi.org/10.1016/j.molcel.2024.05.031 | (pqac-00000000) |
| Key interactions | Asf1 interacts with HIR/Hir1 in histone gene regulation outside S phase and contributes to histone-gene activation in S phase. | Mendiratta excerpt states yeast Asf1 activates histone gene transcription in S phase and represses it outside S phase in combination with Hir1. | Mendiratta et al., 2024, *bioRxiv* | https://doi.org/10.1101/2022.11.30.518476 | (pqac-00000005) |
| Localization | Asf1 contains a functional classical NLS in its highly acidic C-terminal tail that is required for nuclear localization. | Dannah reports deleting the C-tail cNLS makes Asf1 fully cytoplasmic, independent of Vps75. | Dannah, 2024, thesis | https://doi.org/10.32920/25233562.v1 | (pqac-00000008) |
| Localization | The Asf1 C-terminal cNLS is required for full H3K56 acetylation and for interactions with Rad53 and Hir1. | Dannah reports reduced H3K56ac when the cNLS is deleted in VPS75+ cells and abolition of H3K56ac in vps75Δ background; also required for Rad53/Hir1 interaction. | Dannah, 2024, thesis | https://doi.org/10.32920/25233562.v1 | (pqac-00000008) |
| Pathway/module | H3K56 acetylation is a nuclear S-phase mark on newly synthesized H3, enabling efficient handoff of histones to CAF-1 and Rtt106 during DNA replication and repair. | Dannah notes nuclear H3K56ac during S phase and role in transfer to CAF-1/Rtt106; Hst3/Hst4 remove the mark in G2/M. | Dannah, 2024, thesis | https://doi.org/10.32920/25233562.v1 | (pqac-00000011) |
| Phenotypes & quantitative data | asf1Δ causes an S-phase-specific telomere localization defect. | Table/assay values: WT telomere XIV-L peripheral localization (zone 1) 66.0% in G1 and 67.5% in S; asf1 mutant 67.4% in G1 (n=46, p=0.05 vs WT) and 43.1% in S (n=51, p=4.7×10^-4 vs WT). | Hiraga et al., 2008, *Journal of Cell Biology* | https://doi.org/10.1083/jcb.200806065 | (pqac-00000012, pqac-00000016) |
| Phenotypes & quantitative data | Regulated H3K56 acetylation/deacetylation is required for chromosome positioning. | rtt109Δ shows severe telomere localization defects; both H3K56R and H3K56Q nearly abolish proper telomere localization in G1 and S. | Hiraga et al., 2008, *Journal of Cell Biology* | https://doi.org/10.1083/jcb.200806065 | (pqac-00000014) |
| Biological process | Asf1 is required for perinuclear localization of the ETC6 chromatin domain across interphase. | asf1 deletion randomizes ETC6 positioning; rtt109 mutants also lose peripheral positioning, linking Asf1-mediated H3K56ac to higher-order chromosome organization. | Hiraga et al., 2008, *Journal of Cell Biology* | https://doi.org/10.1083/jcb.200806065 | (pqac-00000013) |
| Key interactions | Asf1 is required for efficient Rtt109 activity and H3K56ac; Vps75 supports Rtt109 but cannot fully replace Asf1. | Dannah: loss of Asf1 markedly diminishes Rtt109 activity/H3K56ac; Hiraga: asf1 vps75 double mutant phenocopies strong localization defects. | Dannah, 2024, thesis; Hiraga et al., 2008, *J Cell Biol* | https://doi.org/10.32920/25233562.v1; https://doi.org/10.1083/jcb.200806065 | (pqac-00000010, pqac-00000012) |
| Recent (2023-2024) developments | New structural work strengthens the model that Asf1 engages the HIR complex in replication-independent chromatin assembly. | Kim 2024 provides structural/biochemical evidence for Asf1 binding to HIR-related machinery and supports replication-independent H3–H4 deposition and promoter fidelity roles. | Kim et al., 2024, *Molecular Cell* | https://doi.org/10.1016/j.molcel.2024.05.031 | (pqac-00000000, pqac-00000004) |
| Recent (2023-2024) developments | New localization work identifies a yeast-specific Asf1 cNLS in the acidic tail and links localization directly to H3K56ac competence. | Dannah 2024 reports C-tail cNLS, cytoplasmic mislocalization upon deletion, and H3K56ac defects tied to the motif. | Dannah, 2024, thesis | https://doi.org/10.32920/25233562.v1 | (pqac-00000008) |
| Recent (2023-2024) developments | Current cross-species work reiterates that budding-yeast Asf1 promotes H3K56ac yet is dispensable for viability/growth in S. cerevisiae. | Ding 2025 contrasts S. cerevisiae with fission yeast, noting Asf1 is dispensable for growth in budding yeast while retaining conserved chaperone/H3K56ac functions. | Ding et al., 2025, *Nucleic Acids Research* | https://doi.org/10.1093/nar/gkaf036 | (pqac-00000006) |


*Table: This table summarizes experimentally supported functional annotation for Saccharomyces cerevisiae Asf1 (UniProt P32447), emphasizing molecular function, pathways, localization, interactions, phenotypes, and recent 2023–2024 developments. It is useful as a compact evidence map for narrative gene-function reporting.*