(620c) Transcriptional Effects of Crp* Expression In Escherichia Coli

Escherichia coli exhibits diauxic growth in sugar mixtures due to CRP-mediated catabolite repression and inducer exclusion related to phosphotransferase system enzyme activity. Replacement of the native crp gene with a catabolite repression mutant (referred to as crp*) alleviates diauxic growth effects in E. coli and enables co-utilization of glucose and other sugars. While previous studies have examined the effects of expressing CRP* mutants on the expression of specific catabolic genes, little is known about the global transcriptional effects of CRP* expression. In this study, we compare the transcriptome of E. coli W3110 (expressing wild-type CRP) to that of mutant strain PC05 (expressing CRP*) in the presence and absence of glucose. While the simplest model of CRP*-mediated gene expression assumes insensitivity to glucose (or cAMP), our results show that gene expression in the context of CRP* is very different from that of wild-type in the absence of glucose, and is influenced by the presence of glucose. Approximately 400 genes were found to respond differently to glucose in PC05 compared to W3110. While most genes upregulated by glucose in W3110 are also upregulated by glucose in PC05, the glucose effect is significantly suppressed in PC05. We will present a detailed transcription analysis and relate these results to several important phenotypic differences between W3110 and PC05.