SAGA complex subunit SUS1

UniProtKB accession:  Q6WNK7

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UniProtKB description:  Involved in mRNA export coupled transcription activation by association with both the TREX-2 and the SAGA complexes (PubMed:14718168, PubMed:15311284, PubMed:18923079). SAGA acts as a general cofactor required for essentially all RNA polymerase II transcription (PubMed:25216679, PubMed:28918903). At the promoters, SAGA is required for transcription pre-initiation complex (PIC) recruitment. It influences RNA polymerase II transcriptional activity through different activities such as TBP interaction (via core/TAF module) and promoter selectivity, interaction with transcription activators (via Tra1/SPT module), and chromatin modification through histone acetylation (via HAT module) and deubiquitination (via DUB module) (PubMed:16855026, PubMed:31969703). SAGA preferentially acetylates histones H3 (to form H3K9ac, H3K14ac, H3K18ac and H3K23ac) and H2B and deubiquitinates histone H2B (PubMed:20395473). SAGA interacts with DNA via upstream activating sequences (UASs) (PubMed:28918903, PubMed:29598828). Also identified in a modified version of SAGA named SALSA or SLIK. The cleavage of SPT7 and the absence of the SPT8 subunit in SLIK neither drive any major conformational differences in its structure compared with SAGA, nor significantly affect HAT, DUB, or DNA-binding activities (PubMed:33864814). Within the SAGA complex, participates in a subcomplex with SGF11, SGF73 and UBP8 required for deubiquitination of H2B and for the maintenance of steady-state H3 methylation levels (PubMed:16855026). The TREX-2 complex functions in docking export-competent ribonucleoprotein particles (mRNPs) to the nuclear entrance of the nuclear pore complex (nuclear basket), by association with components of the nuclear mRNA export machinery (MEX67-MTR2 and SUB2) in the nucleoplasm and the nucleoporin NUP1 at the nuclear basket. TREX-2 participates in mRNA export and accurate chromatin positioning in the nucleus by tethering genes to the nuclear periphery (PubMed:16760982, PubMed:18003937, PubMed:19328066). SUS1 also has a role in mRNP biogenesis and maintenance of genome integrity through preventing RNA-mediated genome instability (PubMed:18667528). Has a role in response to DNA damage induced by methyl methane sulfonate (MMS) and replication arrest induced by hydroxyurea (PubMed:16510898). May also be involved in cytoplasmic mRNA decay by interaction with components of P-bodies (PubMed:20230609).