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Continuous control of flagellar gene expression by the σ 28 –FlgM regulatory circuit in Salmonella enterica
Author(s) -
Saini Supreet,
Floess Emily,
Aldridge Christine,
Brown Jonathon,
Aldridge Phillip D.,
Rao Christopher V.
Publication year - 2011
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2010.07444.x
Subject(s) - biology , salmonella enterica , gene , gene expression , regulation of gene expression , gene regulatory network , computational biology , hierarchy , genetics , regulator gene , flagellum , microbiology and biotechnology , escherichia coli , economics , market economy
Summary The flagellar genes in Salmonella enterica are expressed in a temporal hierarchy that mirrors the assembly process itself. The σ 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 σ 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 σ 28 –FlgM regulatory system and also by rewiring the transcriptional hierarchy. Based on these results, we conclude that the σ 28 –FlgM regulatory circuit continuously senses the HBB assembly process and regulates class 3 gene expression and possibly flagellar numbers in response.