Feaver W J, Svejstrup J Q, Bardwell L, Bardwell A J, Buratowski S, Gulyas K D, Donahue T F, Friedberg E C, Kornberg R D
Department of Cell Biology, Stanford University School of Medicine, California 94305.
Cell. 1993 Dec 31;75(7):1379-87. doi: 10.1016/0092-8674(93)90624-y.
Yeast RNA polymerase II initiation factor b, homolog of human TFIIH, is a protein kinase capable of phosphorylating the C-terminal repeat domain of the polymerase; it possesses a DNA-dependent ATPase activity as well. The 85 kd and 50 kd subunits of factor b are now identified as RAD3 and SSL1 proteins, respectively; both are known to be involved in DNA repair. Factor b interacts specifically with another DNA repair protein, SSL2. The ATPase activity of factor b may be due entirely to that associated with a helicase function of RAD3. Factor b transcriptional activity was unaffected, however, by amino acid substitution at a conserved residue in the RAD3 nucleotide-binding domain, suggesting that the ATPase/helicase function is not required for transcription. These results identify factor b as a core repairosome, which may be responsible for the preferential repair of actively transcribed genes in eukaryotes.
酵母RNA聚合酶II起始因子b是人类TFIIH的同源物，是一种能够磷酸化聚合酶C末端重复结构域的蛋白激酶；它还具有依赖于DNA的ATP酶活性。因子b的85 kd和50 kd亚基现在分别被鉴定为RAD3和SSL1蛋白；已知两者都参与DNA修复。因子b与另一种DNA修复蛋白SSL2特异性相互作用。因子b的ATP酶活性可能完全归因于与RAD3解旋酶功能相关的活性。然而，RAD3核苷酸结合结构域中保守残基的氨基酸取代并未影响因子b的转录活性，这表明转录不需要ATP酶/解旋酶功能。这些结果将因子b鉴定为核心修复体，它可能负责真核生物中活跃转录基因的优先修复。
