Minor Alterations in Core Promoter Element Positioning Reveal Functional Plasticity of a Bacterial Transcription Factor.

ABSTRACT: IscR is a global transcription factor that regulates Fe-S cluster homeostasis and other functions in Escherichia coli by either activating or repressing transcription. While the interaction of IscR with its DNA sites has been studied, less is known about the mechanism of IscR regulation of transcription. Here, we show that IscR recruits RNA polymerase to an activated promoter and that IscR binding compensates for the lack of an optimal RNA polymerase σ⁷⁰ -35 promoter element. We also find that the position of the -35 promoter element within the IscR DNA site impacts whether IscR activates or represses transcription. RNA polymerase binding at a distally positioned -35 element within the IscR site results in IscR activation. Molecular modeling suggests that this position of the -3

SUBMITTER: Chowdhury WP 

PROVIDER: S-EPMC8561392 | biostudies-literature | 2021 Dec

REPOSITORIES: biostudies-literature