Interaction between heat shock transcription factor and transcription initiation complex.

点击翻译按钮获取中文摘要

The transcription activation signals of transcription activators are transmitted to the transcription initiation complex via intermediary factors such as Mediator and TAF(TBP-associated factor). The initiation complex consists of RNA polymerase II and the general transcription factors TBP,TFIIB,TFIIE,TFIIF,and TFIIH. By using the methods of yeast molecular genetics, it has been disclosed that activity of the TFIIH kinase(encoded by the KIN28 gene), which phosphorylates the carboxy-terminal domain(CTD) of RNA polymerase II, is dispensable for activation of several stress responsive genes such as heat shock genes. In this study, I have shown that the Kin28-independent activation of the heat-inducible genes is mediated by the heat shock transaction factor Hsfl. In addition, the general transcription factor IIE, which regulates the kinase activity of Kin28, was dispensable for copper-induced transcription of the CUP1 gene encoding copper metallothionein. Transcription of CUP1 is regulated by Hsfl and Aoe 1(copper-inducible activator). I further analyzed the Kin28-and TFIIE-independent transcription mechanisms and revealed the following. 1)The TFIIE-independent activation of CUP1 is mediated by oertain components of the Mediator complex. 2)The recruitment of TAFs, another well-known intermediary factor, is involved in the Kin28-independent transcription by Hsfl. 3) The C-terminal half of Hsfl has activities to recruit TAFs to a promoter and to undergo transcription independently of Kin28. 4)The C-terminal region of Hsfl contains a novel domain that regulates heat-inducible phosphorylation of Hsfl. These results illustrated that an alternate pathway of transcription reaction, in which a specific domain of activator plays a critical role in abrogation of requirement for subset of general transcription factors that are prerequisites in the main pathway of the transcription reaction.