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Published October 8, 2019 | Submitted
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The transcriptional response of genes to RpoS concentration in Escherichia coli is not determined by core promoter sequences

Abstract

The alternative sigma factor RpoS is an important regulatory protein in Escherichia coli, responsible for mediating the general stress response. RpoS levels vary continuously in response to different stresses. Previous work has shown that genes vary in their responsiveness to increasing RpoS concentrations, with some genes being "sensitive," requiring only a low level of RpoS to be relatively highly expressed, while other genes are "insensitive," only being highly expressed in the presence of high levels of RpoS. In other systems, this type of variation is caused by interactions between the regulatory protein and the DNA it binds. To see if this is the case for RpoS, we measured twelve RpoS binding site mutants for their effects on maximal expression and responsiveness to increasing RpoS concentration. While maximal expression varied over an order of magnitude across these twelve constructs, the responsiveness to increasing RpoS concentration was largely unaffected, suggesting that the RpoS binding site alone is not responsible for a genes' sensitivity or insensitivity to RpoS. In addition, we swapped the RpoS binding region between sensitive and insensitive promoters and found no change in the behavior of the promoter. Taken together, these results argue that differences in sensitivity of the RpoS-dependent promoters are not due to interactions between RpoS and the various DNA sites it binds.

Additional Information

The copyright holder for this preprint is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license. bioRxiv preprint first posted online Oct. 8, 2019. Thanks to Roya Amini-Naieni, Lakshmi Batachari, Carla Becker, Moira Dillon, and Asaul Gonzalez for technical help, and to Jane Liu and Pete Chandrangsu for comments on an earlier version of the manuscript. This work was supported by NSF Grant #1716794 to Dan Stoebel and HHMI Undergraduate Science Education award #52007544 to Harvey Mudd College.

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Created:
August 19, 2023
Modified:
October 18, 2023