Differential protein-DNA contacts for activation and repression by ArgP, a LysR-type (LTTR) transcriptional regulator in Escherichia coli

Publication date: Available online 23 October 2017 Source:Microbiological Research Author(s): Phu Nguyen Le Minh, Cristina Velázquez Ruiz, Steven Vandermeeren, Pamella Abwoyo, Indra Bervoets, Daniel Charlier ArgP is a LysR-type transcriptional regulator (LTTR) that operates with two effector molecules, lysine and arginine, to differentially regulate gene expression. Effector-free ArgP stimulates transcription of all investigated regulon members, except argO, whereas lysine abolishes this effect. Activation of argO, encoding an exporter for arginine and canavanine, is strictly dependent on arginine-bound ArgP. Lysine counteracts this effect and even though lysine-bound ArgP stimulates RNA polymerase recruitment at the argO promoter, the complex is non-productive. It is presently unclear what distinguishes argO from other ArgP targets and how binding of arginine and lysine translates in antagonistic effects on promoter activity. Here we generate high resolution contact maps of effector-free and effector-bound ArgP-DNA interactions and identify the sequence 5′-CTTAT as the consensus recognition motif for ArgP binding. argO is the only operator at which ArgP binding overlaps the −35 promoter element and binding of arginine results in a repositioning of the promoter proximal bound ArgP-arg subunits. This effect was mimicked by the generation of a 10bp insertion mutant (ins-10) in the argO operator that renders its activation by ArgP arginine-independent. ArgP-induced ...
Source: Microbiological Research - Category: Infectious Diseases Source Type: research