Inducer exclusion, by itself, cannot account for the glucose-mediated lac repression of Escherichia coli.

ABSTRACT: The lac operon of Escherichia coli is repressed several 100-fold in the presence of glucose. This repression has been attributed to cAMP receptor protein-mediated inhibition of lac transcription and EIIA^Glc-mediated inhibition of lactose transport (inducer exclusion). The growing evidence against the first mechanism has led to the postulate that the repression is driven by inducer exclusion. Although inducer exclusion reduces the permease activity only 2-fold in fully induced cells, it could be more potent in partially induced cells. Here, we show that even in partially induced cells, inducer exclusion reduces the permease activity no more than 6-fold. Moreover, the repression is so small because these experiments are performed in the presence of chloramphenicol. Indeed, when gl

SUBMITTER: Aggarwal RK 

PROVIDER: S-EPMC8943701 | biostudies-literature | 2022 Mar

REPOSITORIES: biostudies-literature