The role of CopG mediated DNA bending on the regulation of the σ54-dependent promoters in E. coli

Abstract

In order to investigate the role of DNA bending on the regulation of σ54-dependent promoters, we introduced the CopG binding site between the enhancer-like element and the core promoter of glnAp2, nifLp and glnHp2, without changing the distance in between. The expression activities of these homologous promoters were either activated or repressed by the CopG-induced DNA bending in E. coli. In this case, similar regulatory pattern (either activated or repressed) could be observed, when the bending centers from CopG are in integral DNA helixes interval, while opposite regulatory pattern could be observed, when the bending centers from CopG are in integral plus a half DNA helixes interval. These results suggested that CopG-induced DNA bending can exert regulatory effects on the transcription of σ54-dependent promoters probably by altering the relative DNA helix phase of 54 RNA polymerase and NtrC.