Schmid K, Ebner R, Altenbuchner J, Schmitt R, Lengeler J W
Fachbereich Biologie/Chemie, Universität Osnabrück, FRG.
Mol Microbiol. 1988 Jan;2(1):1-8. doi: 10.1111/j.1365-2958.1988.tb00001.x.
The scr genes located on plasmid pUR400 and responsible for sucrose (Scr) metabolism of Escherichia coli K12 and other enteric bacteria have been cloned on a 9.3 kb DNA fragment. The different genes were mapped by transposon insertion mutagenesis, by restriction endonuclease and deletion mapping, and the corresponding gene products were identified. Besides the known structural genes scrA, coding for an EnzymeII(Scr) (45 kD) of the phosphoenolypyruvate-dependent phosphotransferase system (PTS), and scrB, coding for a sucrose 6-phosphate hydrolase (invertase) (55 kD), two new structural genes were discovered. Gene scrK apparently codes for an intracellular and ATP-dependent fructokinase (39 kD), while scrY seems to code for a sucrose porin (58 kD) in the outer cell membrane. No genes for an Enzyme III(Scr) of the PTS or for (a) glycosyltransferase(s) were detected. The four genes form an scr operon (gene order, scrK scrY scrA scrB, transcription from K to B), regulated by a repressor (gene scrR, 37 kD) and inducible by sucrose, fructose and fructose-containing oligosaccharides.
位于质粒pUR400上、负责大肠杆菌K12及其他肠道细菌蔗糖（Scr）代谢的scr基因已被克隆到一段9.3 kb的DNA片段上。通过转座子插入诱变、限制性内切酶和缺失作图对不同基因进行了定位，并鉴定了相应的基因产物。除了已知的结构基因scrA（编码磷酸烯醇丙酮酸依赖性磷酸转移酶系统（PTS）的酶II（Scr）（45 kD））和scrB（编码蔗糖6-磷酸水解酶（转化酶）（55 kD））外，还发现了两个新的结构基因。基因scrK显然编码一种细胞内且依赖ATP的果糖激酶（39 kD），而scrY似乎编码外细胞膜中的一种蔗糖孔蛋白（58 kD）。未检测到PTS的酶III（Scr）或糖基转移酶的基因。这四个基因形成一个scr操纵子（基因顺序为scrK scrY scrA scrB，从K到B转录），受一种阻遏物（基因scrR，37 kD）调控，可被蔗糖、果糖和含果糖的寡糖诱导。
