Winslow R H, Julien B, Calendar R, Christie G E
Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, Virginia 23298-0678, USA.
J Bacteriol. 1998 Nov;180(22):6064-7. doi: 10.1128/JB.180.22.6064-6067.1998.
The Serratia marcescens extracellular nuclease gene, nucA, is positively regulated by the product of the nucC gene. In this study, the upstream region required for NucC-dependent nuclease expression was defined by using fusions to the gene encoding chloramphenicol acetyltransferase (cat). This sequence includes an element of hyphenated dyad symmetry identified previously as the binding site for the P2 Ogr family of activators. Footprint analysis confirmed that members of this family of activator proteins bind to this site, protecting a region between -76 and -59 relative to the start of transcription. The activator binding site in the nucA promoter lies one turn of the helix upstream from the corresponding sites in the P2 and P4 late promoters. The effects of deletions between the downstream end of the activator binding site and the putative -35 region are consistent with a strict helical phasing requirement for activation.
粘质沙雷氏菌胞外核酸酶基因nucA受nucC基因产物的正调控。在本研究中，通过与编码氯霉素乙酰转移酶（cat）的基因融合，确定了NucC依赖性核酸酶表达所需的上游区域。该序列包含一个先前被鉴定为P2 Ogr激活剂家族结合位点的断连二元对称元件。足迹分析证实，该激活剂蛋白家族成员结合到该位点，保护相对于转录起始点-76至-59之间的区域。nucA启动子中的激活剂结合位点位于P2和P4晚期启动子相应位点上游一圈螺旋处。激活剂结合位点下游末端与假定的-35区域之间缺失的影响与激活所需的严格螺旋相位要求一致。
