Chang C H, Winans S C
Section of Microbiology, Cornell University, Ithaca, New York 14853, USA.
J Bacteriol. 1996 Aug;178(15):4717-20. doi: 10.1128/jb.178.15.4717-4720.1996.
Transcription of the virG gene initiates from two tandem promoters, designated P1 and P2, that are located 50 nucleotides apart. Transcription of the P2 promoter is induced by extracellular acidity. cis-acting sites required for P2 activity were identified by constructing and assaying a series of 5' and 3' resections and site-directed nucleotide substitutions. Nucleotides between positions -9 and -37 were sufficient for regulated promoter activity. Within this region, nucleotide substitutions at the predicted -10 and -35 regions strongly reduced P2 expression. In addition, alterations in the region between nucleotides -24 and -32 also eliminated or strongly reduced promoter activity. These data suggest that this promoter may be regulated by a positive transcription factor that binds to nucleotide residues in this interval.
virG基因的转录起始于两个串联启动子，分别命名为P1和P2，它们相距50个核苷酸。P2启动子的转录受细胞外酸性环境诱导。通过构建和检测一系列5'端和3'端切除片段以及定点核苷酸替换，确定了P2活性所需的顺式作用位点。-9至-37位之间的核苷酸对于启动子活性的调控是足够的。在该区域内，预测的-10和-35区域的核苷酸替换极大地降低了P2的表达。此外，-24至-32位核苷酸之间区域的改变也消除或极大地降低了启动子活性。这些数据表明，该启动子可能受一个与该区间核苷酸残基结合的正转录因子调控。
