Monedero V, Postma P W, Pérez-Martínez G
Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos, 46100-Burjassot, Valencia, Spain.
J Bacteriol. 1998 Oct;180(19):5247-50. doi: 10.1128/JB.180.19.5247-5250.1998.
A DNA fragment from Lactobacillus casei that restores growth to Escherichia coli and Salmonella typhimurium ptsH mutants on glucose and other substrates of the phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS) has been isolated. These mutants lack the HPr protein, a general component of the PTS. Sequencing of the cloned fragment revealed the absence of ptsH homologues. Instead, the complementation ability was located in a 120-bp fragment that contained a sequence homologue to the binding site of the Cra regulator from enteric bacteria. Experiments indicated that the reversion of the ptsH phenotype was due to a titration of the Cra protein, which allowed the constitutive expression of the fructose operon.
已从干酪乳杆菌中分离出一段DNA片段，该片段可使大肠杆菌和鼠伤寒沙门氏菌ptsH突变体在葡萄糖及磷酸烯醇式丙酮酸：碳水化合物磷酸转移酶系统（PTS）的其他底物上恢复生长。这些突变体缺乏HPr蛋白，即PTS的一种通用成分。对克隆片段进行测序后发现不存在ptsH同源物。相反，互补能力位于一个120 bp的片段中，该片段包含与肠道细菌Cra调节因子结合位点的序列同源物。实验表明，ptsH表型的回复是由于Cra蛋白的滴定，这使得果糖操纵子能够组成型表达。
