PEP群易位
突变体
生物
糖
大肠杆菌
操纵子
生物化学
酶
突变
磷酸烯醇丙酮酸羧激酶
磷酸转移酶
细菌
微生物学
基因
遗传学
作者
Huitae Min,Yeong‐Jae Seok
标识
DOI:10.1111/1462-2920.16244
摘要
Most bacteria use the phosphoenolpyruvate (PEP):sugar phosphotransferase system (PTS) to catalyse coupled transport and phosphorylation of sugars. The PTS consists of several sugar-specific components (enzyme IIs) and two general components: enzyme I, encoded by ptsI, and HPr, encoded by ptsH, which are common to most PTS carbohydrates. Although both enzyme I and HPr are believed to be required to utilize these PTS sugars, an E. coli ptsH mutant has been reported to exhibit a leaky growth phenotype on these sugars. Here, we show that this phenomenon occurs because the ptsH mutant undergoes adaptive mutations in the presence of PTS sugars within a few generation times. The ptsH mutant cells once exposed to a PTS sugar showed a growth rate similar to that of the wild-type strain when transferred to fresh medium supplemented with the same PTS sugar, suggesting the acquisition of additional genetic variations. Genome sequencing revealed that the PTS sugar-adapted variants harboured loss-of-function mutations in cra, which increased expression of the fruBKA operon. Our results suggest that the presence of a PTS sugar can exert a strong selective pressure when a general PTS component is defective.
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