| Aspect | Key points | Evidence/citation IDs | Key sources with year and URL (if available) |
|---|---|---|---|
| Complex membership | Spt16 is the large, essential subunit of the conserved yeast FACT histone chaperone complex; in *S. cerevisiae* it forms a heterodimer with Pob3, and budding-yeast FACT function additionally depends on the HMGB protein Nhp6 for efficient nucleosome engagement. Spt16 is also referred to as Cdc68, matching the yeast FACT subunit identity rather than metazoan SPT16 orthologs. | (pqac-00000000, pqac-00000007, pqac-00000012) | Takahata & Murakami 2023, *Biomolecules*, https://doi.org/10.3390/biom13020377; Jang et al. 2025, *Nucleic Acids Research*, https://doi.org/10.1101/2024.06.17.599424 |
| Domains | Supported domain architecture includes: N-terminal peptidase-like/pita-bread fold domain; dimerization domain; middle domain; and acidic/disordered C-terminal region. The peptidase-like fold appears catalytically inactive and repurposed for chromatin functions. The middle domain binds H3-H4, whereas the acidic C-terminus binds H2A-H2B. | (pqac-00000001, pqac-00000011, pqac-00000020) | Schweighofer 2025, unknown journal; Hou 2025, unknown journal |
| Binding specificity | FACT/Spt16 is atypical among histone chaperones because it can engage both H3-H4 and H2A-H2B. In budding yeast, the Spt16 N-terminal domain is linked to H3/H4 interactions, the middle/tandem PH-like region binds H3-H4, and the acidic C-terminal tail binds H2A-H2B and can act as a DNA placeholder on partially unwrapped nucleosomes. FACT preferentially stabilizes partially unwrapped nucleosome intermediates rather than fully wrapped nucleosomes. | (pqac-00000001, pqac-00000008, pqac-00000012) | Takahata & Murakami 2023, https://doi.org/10.3390/biom13020377; Hou 2025, unknown journal; Schweighofer 2025, unknown journal |
| Transcription roles | In yeast, Spt16/FACT is a nucleosome-templated transcription factor that promotes productive RNAPII elongation, supports nucleosome disassembly and reassembly during polymerase passage, suppresses cryptic initiation, and contributes to promoter function/PIC formation. Spt16 is recruited near promoters via a partially unwrapped +1 nucleosome and travels across gene bodies with help from Chd1. | (pqac-00000002, pqac-00000006, pqac-00000015) | Byrd et al. 2024, *BMC Research Notes*, https://doi.org/10.1186/s13104-024-06872-y; Hou 2025, unknown journal |
| Replication roles | Spt16 also functions at replication forks. Its N-terminal domain binds Tof1 and MCM2-7, linking FACT to the fork protection complex/replisome; FACT also interacts with DNA polymerase α. Recent replication-focused work places FACT ahead of the fork, with the Spt16 middle domain contacting H3-H4 and the C-terminus contacting H2A-H2B, consistent with roles in parental histone disassembly/recycling and nucleosome reassembly during DNA synthesis. | (pqac-00000005, pqac-00000016, pqac-00000019) | Zhang et al. 2024, bioRxiv, https://doi.org/10.1101/2024.08.08.607175; Dolson 2024, unknown journal |
| Heterochromatin / euchromatin roles | Authoritative 2023 review evidence supports an asymmetry in yeast FACT roles: in budding yeast, FACT promotes euchromatic/promoter chromatin activation, including SBF/MBF-dependent G1/S genes, whereas no clear role is reported for Sir-dependent heterochromatin silencing; in fission yeast, by contrast, FACT contributes to heterochromatin stability with Swi6/HP1. This distinction is important when annotating *S. cerevisiae* Spt16 specifically. | (pqac-00000009, pqac-00000012) | Takahata & Murakami 2023, *Biomolecules*, https://doi.org/10.3390/biom13020377 |
| Localization | The supported localization is nuclear/chromatin-associated. Functionally, Spt16/FACT localizes to transcribed genes, promoters/+1 nucleosomes, and replication forks via interactions with Tof1/MCM; proteomics and other studies also report centromeric enrichment of FACT, though the centromere-specific function remains unresolved. | (pqac-00000006, pqac-00000013, pqac-00000019) | Byrd et al. 2024, https://doi.org/10.1186/s13104-024-06872-y; Schweighofer 2025, unknown journal |
| Recent 2023-2024 findings | 2023 review work synthesized a model in which budding-yeast Spt16/Pob3/Nhp6 reorganizes nucleosomes by DNA loosening, H2A-H2B displacement, and redeposition. A 2023 primary study linked H2B Arg95-dependent recruitment of Spt16 to expression of the pheromone-pathway scaffold gene *STE5*. A 2024 study showed one PMA1 3' internal deletion modestly increased Spt16 retention at the gene end, supporting sequence contributions to yFACT dissociation. 2024 replication studies tied the Spt16 N-terminus to parental histone recycling and replisome coupling. | (pqac-00000004, pqac-00000012, pqac-00000015, pqac-00000016) | Sulaiman et al. 2023, *Scientific Reports*, https://doi.org/10.1038/s41598-023-37339-y; Takahata & Murakami 2023, https://doi.org/10.3390/biom13020377; Byrd et al. 2024, https://doi.org/10.1186/s13104-024-06872-y; Dolson 2024, unknown journal |
| Quantitative stats | Quantitative findings available in the snippets are limited but include: the H2B R95A mutant lost expression of 26 pheromone-response genes, and rapamycin induced roughly 3- to 4-fold *CLN2* expression in *ste5Δ* cells within 30 min; Pol α/primase products comprise an 8-10 nt RNA primer extended to ~20-35 nt total; Byrd et al. generated fourteen 68-bp deletions across the PMA1 3' region, with one deletion causing a modest increase in Spt16 occupancy. Most other retrieved yeast-specific findings were qualitative or structural rather than numerically quantified in the available snippets. | (pqac-00000004, pqac-00000005, pqac-00000015) | Sulaiman et al. 2023, https://doi.org/10.1038/s41598-023-37339-y; Zhang et al. 2024, https://doi.org/10.1101/2024.08.08.607175; Byrd et al. 2024, https://doi.org/10.1186/s13104-024-06872-y |


*Table: This table summarizes the supported functional annotation of Saccharomyces cerevisiae Spt16/Cdc68 as the FACT complex subunit, emphasizing domains, binding specificity, transcription and replication roles, localization, and recent 2023–2024 findings. It is useful as a compact evidence map tied directly to available citation IDs and source URLs.*