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Continuous control of flagellar gene expression by the σ28–FlgM regulatory circuit in Salmonella enterica

Lookup NU author(s): Christine Aldridge, Dr Jonathan Brown, Dr Phillip AldridgeORCiD


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The flagellar genes in Salmonella enterica are expressed in a temporal hierarchy that mirrors the assembly process itself. The sigma(28)-FlgM regulatory circuit plays a key role in controlling this temporal hierarchy. This circuit ensures that the class 3 genes are expressed only when the hook-basal body (HBB), a key intermediate in flagellar assembly, is complete. In this work, we investigated the role of the sigma(28)-FlgM regulatory circuit in controlling the timing and magnitude of class 3 gene expression using a combination of mathematical modelling and experimental analysis. Analysis of the model predicted that this circuit continuously controls class 3 gene expression in response to HBB abundance. We experimentally validated these predictions by eliminating different components of the sigma(28)-FlgM regulatory system and also by rewiring the transcriptional hierarchy. Based on these results, we conclude that the sigma(28)-FlgM regulatory circuit continuously senses the HBB assembly process and regulates class 3 gene expression and possibly flagellar numbers in response.

Publication metadata

Author(s): Saini S, Floess E, Aldridge C, Brown J, Aldridge PD, Rao CV

Publication type: Article

Publication status: Published

Journal: Molecular Microbiology

Year: 2011

Volume: 79

Issue: 1

Pages: 264-278

Print publication date: 17/11/2010

ISSN (print): 0950-382X

ISSN (electronic): 1365-2958

Publisher: Wiley-Blackwell Publishing Ltd.


DOI: 10.1111/j.1365-2958.2010.07444.x


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Funder referenceFunder name
Department of Chemical & Biomolecular Engineering at the University of Illinois
CBET 0644744National Science Foundation
GM083601Public Health Service
GM054365Public Health Service