Koch K A, Allard S, Santoro N, Côté J, Thiele D J
Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109-0606, USA.
Mol Microbiol. 2001 Jun;40(5):1165-74. doi: 10.1046/j.1365-2958.2001.02458.x.
The yeast Candida glabrata rapidly autoactivates transcription of the AMT1 gene in response to potentially toxic copper levels through the copper-inducible binding of the Amt1 transcription factor to a metal response element (MRE) within a positioned nucleosome. Our previous studies have characterized the role of a 16 bp homopolymeric dA:dT DNA structural element in facilitating rapid Amt1 access to the AMT1 promoter nucleosomal MRE. In this study, we have used the genetically more facile yeast Saccharomyces cerevisiae to identify additional cellular factors that are important for promoting rapid autoactivation of the AMT1 gene in response to toxic copper levels. We demonstrate that the Swi/Snf nucleosome remodelling complex and the histone acetyltransferase Gcn5 are both essential for AMT1 gene autoregulation, and that the requirement for these chromatin remodelling factors is target gene specific. Chromatin accessibility measurements performed in vitro and in vivo indicate that part of the absolute requirement for these factors is derived from their involvement in facilitating nucleosomal access to the AMT1 promoter MRE. Additionally, these data implicate the involvement of Swi/Snf and Gcn5 at multiple levels of AMT1 gene autoregulation.
光滑念珠菌酵母可通过Amt1转录因子与定位核小体内的金属反应元件（MRE）的铜诱导结合，对潜在有毒的铜水平做出反应，迅速自动激活AMT1基因的转录。我们之前的研究已经表征了一个16bp的同聚dA:dT DNA结构元件在促进Amt1快速进入AMT1启动子核小体MRE中的作用。在本研究中，我们使用了遗传操作更简便的酿酒酵母来鉴定其他对响应有毒铜水平促进AMT1基因快速自动激活很重要的细胞因子。我们证明Swi/Snf核小体重塑复合体和组蛋白乙酰转移酶Gcn5对AMT1基因的自动调节都是必不可少的，并且对这些染色质重塑因子的需求是靶基因特异性的。在体外和体内进行的染色质可及性测量表明，对这些因子的绝对需求部分源于它们参与促进核小体进入AMT1启动子MRE。此外，这些数据表明Swi/Snf和Gcn5参与了AMT1基因自动调节的多个层面。
