O'Brien T, Tjian R
Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley 94720, USA.
Mol Cell. 1998 May;1(6):905-11. doi: 10.1016/s1097-2765(00)80089-1.
The largest subunit of the human transcription factor TFIID, TAFII250, was previously reported to contain serine/threonine kinase domains that can autophosphorylate and transphosphorylate the large subunit of the basal factor TFIIF. Here, we identify the regions of the N-terminal kinase domain (amino acids 1-414) necessary for kinase activity and examine its function in vivo. Point mutations within two patches of amino acids in the kinase domain decrease both autophosphorylation and transphosphorylation activities. Importantly, we find that TAFII250-bearing mutations within the N-terminal kinase domain exhibit a significantly reduced ability to rescue ts13 cells that express a temperature-sensitive TAFII250. Moreover, transcription from the cyclin A and cdc2 promoters becomes impaired when cotransfected with hTAFII250 containing inactive forms of the N-terminal kinase domain. Our results suggest that the TAFII250 kinase activity is required to direct transcription of at least some genes in vivo.
人类转录因子TFIID的最大亚基TAFII250，先前报道其含有丝氨酸/苏氨酸激酶结构域，该结构域可进行自磷酸化并对基础因子TFIIF的大亚基进行转磷酸化。在此，我们确定了激酶活性所必需的N端激酶结构域（氨基酸1 - 414）区域，并在体内研究了其功能。激酶结构域中两个氨基酸片段内的点突变降低了自磷酸化和转磷酸化活性。重要的是，我们发现N端激酶结构域内带有突变的TAFII250拯救表达温度敏感型TAFII250的ts13细胞的能力显著降低。此外，当与含有无活性N端激酶结构域形式的hTAFII250共转染时，细胞周期蛋白A和cdc2启动子的转录受到损害。我们的结果表明，TAFII250激酶活性是体内指导至少某些基因转录所必需的。
