Abstract

The sdaA gene of Escherichia coli encodes L-serine deaminase (L-SD), which degrades L-serine to ammonia and pyruvate. LRP represses the expression of both L-SD and sdaA . CRP was assumed to affect sdaA transcription, but this had not been proven. I demonstrated here that both CRP and LRP were involved in L-SD and sdaA expression. LRP repressed L-SD expression and sdaA transcription. CRP activated L-SD expression depending on the presence of LRP but did not affect sdaA transcription. The genes for serA and metK are known to be regulated by LRP and are proposed to be regulated by CRP. CRP activated the serA P2 promoter. However, it did not affect serA expression overall. CRP was also involved in the regulation of metK expression through an unclear mechanism. By providing ptsG expression on a plasmid, I identified one factor causing the slow growth rate of crp mutants. The rate of glucose uptake was suggested to affect the growth rate of crp mutants.