Nelson S O, Schuitema A R, Benne R, van der Ploeg L H, Plijter J S, Aan F, Postma P W
EMBO J. 1984 Jul;3(7):1587-93. doi: 10.1002/j.1460-2075.1984.tb02015.x.
The phosphoenolpyruvate:glucose phosphotransferase system (PTS) of Salmonella typhimurium is involved both in glucose transport and in the regulation and synthesis of adenylate cyclase and several transport systems. The crr gene has been implicated in this regulating mechanism. A 9.6-kb segment of the S. typhimurium chromosome containing the crr gene was cloned in pAT153. The cloned fragment also complemented cysA mutations but did not contain a functional pts operon which is closely linked to the crr gene and codes for two enzymes of the PTS. Although cysA and crr have been reported to be located on opposite sides of ptsHI, our results suggest that the correct gene order is cysK-ptsHI-crr-cysA. Expression of crr plasmids in a maxicell system yielded two proteins which reacted with specific anti-serum against IIIGlc. The apparent mol. wts. in SDS-polyacrylamide gels were 20 000 and 21 000, the former corresponding to the major band of purified IIIGlc. Both forms were also observed in bacterial extracts and purified IIIGlc. The crr gene was localized on a 1-kb EcoRI-EcoRV fragment of the 9.6-kb insert and sequenced. It codes for a single protein (18 556 D) containing 169 amino acid residues and identified as IIIGlc.
葡萄糖磷酸转移酶系统（PTS）既参与葡萄糖转运，也参与腺苷酸环化酶及几种转运系统的调节与合成。crr基因与这种调节机制有关。包含crr基因的鼠伤寒沙门氏菌染色体9.6 kb片段被克隆到pAT153中。克隆片段也能互补cysA突变，但不包含与crr基因紧密连锁且编码PTS两种酶的功能性pts操纵子。尽管据报道cysA和crr位于ptsHI的两侧，但我们的结果表明正确的基因顺序是cysK - ptsHI - crr - cysA。crr质粒在大细胞系统中的表达产生了两种与抗IIIGlc特异性抗血清反应的蛋白质。在SDS -聚丙烯酰胺凝胶中的表观分子量分别为20000和21000，前者对应纯化的IIIGlc主带。在细菌提取物和纯化的IIIGlc中也观察到了这两种形式。crr基因定位于9.6 kb插入片段的1 kb EcoRI - EcoRV片段上并进行了测序。它编码一种含有169个氨基酸残基的单一蛋白质（18556 D），并被鉴定为IIIGlc。
