DNA distortion and multimerization: novel functions of the glutamine-rich domain of GAGA factor.
DNA distortion and multimerization: novel functions of the glutamine-rich domain of GAGA factor.
复制标题
DNA 扭曲和多聚化：GAGA 因子富含谷氨酰胺结构域的新功能。
DOI：
10.1006/jmbi.1998.2356
复制
发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Lis,JT
中科院分区：
文献类型：
--
作者：
Wilkins,RC;Lis,JT
GAF是果蝇体内的一种重要蛋白质，对多种基因的转录调控具有重要作用。GAF对染色质结构和启动子功能的影响一直是人们关注的主题，但对其实际机制和单个GAF结构域对其功能的具体贡献还知之甚少。GAF的DNA结合活性由单个锌指结合域(ZN)确定，但POZ/BTB和谷氨酰胺结构域(Q)的功能仍不清楚。在这里，我们报道了GAF的Q结构域的三种不同的活性：启动子扭曲、单链结合和多聚化。在体外，GAF与HSP70启动子结合可产生延长的DNase I保护和KMnO4超敏反应。这些活性需要GAF的锌结构域和Q结构域，并且独立于POZ/BTB结构域。GAF也具有单链DNA结合亲和力，就像富含Q的区域一样。GAF在体外和体内形成多聚体，Q结构域本身形成多聚体。因此，由Q结构域介导的蛋白质-蛋白质相互作用可能至少部分地对GAF的多聚化能力负责。我们根据这些发现在GAF介导的转录调控中的可能功能来讨论这些发现。
GAGA factor (GAF) is an essential protein in Drosophila melanogaster, important for the transcriptional regulation of numerous genes. The effect of GAF on chromatin structure and promoter function has been the subject of much attention, yet little is known of the actual mechanism and the specific contributions of individual GAF domains to its function. The DNA-binding activity of GAF, as specified by the single zinc finger binding domain (Zn), has been examined in some detail; however, the functions of the POZ/BTB and glutamine domain (Q) remain poorly understood. Here, we report three separate activities of the Q domain of GAF; promoter distortion, single-strand binding, and multimerization. In vitro, GAF binding to the hsp70 promoter produces extended DNase I protection and KMnO4hypersensitivity. These activities require both the Zn domain and Q domain of GAF, and appear independent of the POZ/BTB domain. GAF also has a single-stranded DNA binding affinity, as does the Q-rich region alone. GAF forms multimers both in vitro and in vivo, and the Q domain itself forms multimers. Protein-protein interactions mediated by the Q domain may, therefore, be at least partially responsible for the multimerization capabilities of GAF. We discuss these findings in the context of their possible function in GAF mediated transcriptional regulation.