title: Continuous control of flagellar gene expression by the σ28-FlgM regulatory circuit in Salmonella enterica.
abstract: 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.
authors.affiliation: Department of Chemical & Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Supreet
authors.initials: S
authors.lastname: Saini
authors.forename: Emily
authors.initials: E
authors.lastname: Floess
authors.forename: Christine
authors.initials: C
authors.lastname: Aldridge
authors.forename: Jonathon
authors.initials: J
authors.lastname: Brown
authors.forename: Phillip D
authors.initials: PD
authors.lastname: Aldridge
authors.forename: Christopher V
authors.initials: CV
authors.lastname: Rao
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D005408:Flagellin / Q000096:biosynthesis* / Q000235:genetics; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D008962:Models, Theoretical; D012486:Salmonella typhimurium / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D012808:Sigma Factor / Q000378:metabolism*; D013997:Time Factors
chemical_list: D001426:Bacterial Proteins; C064971:FliA protein, Bacteria; D012808:Sigma Factor; D005408:Flagellin; C071266:FlgM protein, Bacteria