Author:
Aldridge Phillip D.,Karlinsey Joyce E.,Aldridge Christine,Birchall Christopher,Thompson Danielle,Yagasaki Jin,Hughes Kelly T.
Abstract
The σ28 protein is a member of the bacterial σ70-family of transcription factors that directs RNA polymerase to flagellar late (class 3) promoters. The σ28 protein is regulated in response to flagellar assembly by the anti-σ28 factor FlgM. FlgM inhibits σ28-dependent transcription of genes whose products are needed late in assembly until the flagellar basal motor structure, the hook-basal body (HBB), is constructed. A second function for the σ28 transcription factor has been discovered: σ28 facilitates the secretion of FlgM through the HBB, acting as the FlgM Type III secretion chaperone. Transcription-specific mutants in σ28 were isolated that remained competent for FlgM-facilitated secretion separating the transcription and secretion-facilitation activities of σ
28. Conversely, we also describe the isolation of mutants in σ28 that are specific for FlgM-facilitated secretion. The data demonstrate that σ28 is the Type III secretion chaperone for its own anti-sigma factor FlgM. Thus, a novel role for a σ70-family transcription factor is described.
Publisher
Cold Spring Harbor Laboratory
Subject
Developmental Biology,Genetics
Cited by
66 articles.
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