Wehmeier U F, Nobelmann B, Lengeler J W
Fachbereich Biologie/Chemie, Universität Osnabrück, Germany.
J Bacteriol. 1992 Dec;174(23):7784-90. doi: 10.1128/jb.174.23.7784-7790.1992.
The sor genes for L-sorbose (Sor) degradation of Escherichia coli EC3132, a wild-type strain, have been cloned on a 10.8-kbp fragment together with parts of the metH gene. The genes were mapped by restriction analysis, by deletion mapping, and by insertion mutagenesis with Tn1725. Seven sor genes with their corresponding gene products have been identified. They form an operon (gene order sorCpCDFBAME) inducible by L-sorbose, and their products have the following functions: SorC (36 kDa), regulatory protein with repressor-activator functions; SorD (29 kDa), D-glucitol-6-phosphate dehydrogenase; SorF and SorB (14 and 19 kDa, respectively), and SorA and SorM (27 and 29 kDa, respectively), two soluble and two membrane-bound proteins, respectively, of an L-sorbose phosphotransferase transport system; SorE (45 kDa), sorbose-1-phosphate reductase. The sor operon from E. coli EC3132 thus is identical to the operon from Klebsiella pneumoniae KAY2026. On the basis of restriction mapping followed by Southern hybridization experiments, the sor genes were mapped at 91.2 min on the chromosome, 3.3 kbp downstream of the metH-iclR gene cluster, and shown to be transcribed in a counterclockwise direction. The chromosomal map of the Sor+ strain EC3132 differs from that of the Sor- strain K-12 in approximately 8.6 kbp.
野生型大肠杆菌EC3132中负责L-山梨糖（Sor）降解的sor基因已与metH基因的部分片段一起克隆到一个10.8kbp的片段上。通过限制性分析、缺失作图以及用Tn1725进行插入诱变对这些基因进行了定位。已鉴定出7个sor基因及其相应的基因产物。它们形成一个由L-山梨糖诱导的操纵子（基因顺序为sorCpCDFBAME），其产物具有以下功能：SorC（36kDa），具有阻遏物-激活物功能的调节蛋白；SorD（29kDa），D-葡萄糖醇-6-磷酸脱氢酶；SorF和SorB（分别为14kDa和19kDa），以及SorA和SorM（分别为27kDa和29kDa），分别是L-山梨糖磷酸转移酶运输系统的两种可溶性蛋白和两种膜结合蛋白；SorE（45kDa），山梨糖-1-磷酸还原酶。因此，大肠杆菌EC3132的sor操纵子与肺炎克雷伯菌KAY2026的操纵子相同。基于限制性图谱分析以及随后的Southern杂交实验，sor基因定位于染色体上91.2分钟处，在metH-iclR基因簇下游3.3kbp处，并显示其转录方向为逆时针。Sor+菌株EC3132的染色体图谱与Sor-菌株K-12的染色体图谱在约8.6kbp处存在差异。
