Structural and Functional Analysis of the Promoter Region of the Escherichia coli udp Gene

Abstract

Effect of mutations in the –10 and –35 regions of the udpgene promoter on the nature of its regulation by CytR and CRP proteins was studied. In studies of expression of mutant promoters, competition between RNA polymerase and the CytR repressor for the promoter region of the udp gene was shown. In the presence of the improved –10 region, the introduction of a substitution 15C → T (that is the presence of the elongated Pribnow block) resulted in the CRP-independent transcription of the udp gene promoter. The binding site CRP2 was shown to be indispensable for the maximum promoter activation by the transcription-activating cAMP–CRP complex. Both positive (cAMP–CRP complex) and negative (CytR) regulation of the promoter was virtually fully abolished after the introduction of mutations leading to the creation of canonical sequences in –10 and –35 promoter regions.