Related Experiment Video

Updated: Aug 6, 2026

Generation of Null Mutants to Elucidate the Role of Bacterial Glycosyltransferases in Bacterial Motility
12:29

Generation of Null Mutants to Elucidate the Role of Bacterial Glycosyltransferases in Bacterial Motility

Published on: March 11, 2022

The flagellar-specific transcription factor, sigma28, is the Type III secretion chaperone for the flagellar-specific

Phillip D Aldridge1, Joyce E Karlinsey, Christine Aldridge

  • 1Institute for Cell and Molecular Biosciences, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK. p.d.aldridge@ncl.ac.uk

Genes & Development
|August 17, 2006
PubMed

Insights

The sigma(28) protein, a bacterial transcription factor, acts as a chaperone for its own anti-sigma factor, FlgM. This study separates sigma(28)

Area of Science:

  • Molecular Biology
  • Bacterial Genetics
  • Protein Function

Background:

  • The sigma(28) protein is a sigma(70)-family transcription factor regulating bacterial flagellar gene expression.
  • FlgM is an anti-sigma(28) factor that inhibits sigma(28)-dependent transcription until flagellar basal body construction.
  • Flagellar assembly requires precise temporal regulation of gene expression.

Purpose of the Study:

  • To investigate the dual functions of the sigma(28) protein in transcription and secretion.
  • To elucidate the role of sigma(28) in the secretion of its regulator, FlgM.
  • To characterize mutants affecting sigma(28)'s transcription and secretion-facilitation activities.

Main Methods:

  • Isolation and characterization of transcription-specific sigma(28) mutants.
  • Isolation and characterization of secretion-specific sigma(28) mutants.
  • Analysis of sigma(28)'s interaction with FlgM and the Type III secretion system.

Main Results:

  • Sigma(28) possesses a novel function in facilitating FlgM secretion through the hook-basal body (HBB).
  • Mutants were identified that separate sigma(28)'s transcriptional activity from its secretion-chaperone function.
  • Data confirm sigma(28) acts as the Type III secretion chaperone for FlgM.

Conclusions:

  • Sigma(28) functions not only as a transcription factor but also as a Type III secretion chaperone for its anti-sigma factor, FlgM.
  • This dual role highlights a novel mechanism for regulating gene expression and protein secretion in bacteria.
  • The findings expand the known functions of sigma(70)-family transcription factors.

More Related Videos

Applying Live Cell Imaging and Cryo-Electron Tomography to Resolve Spatiotemporal Features of the Legionella pneumophila Dot/Icm Secretion System09:12

Applying Live Cell Imaging and Cryo-Electron Tomography to Resolve Spatiotemporal Features of the Legionella pneumophila Dot/Icm Secretion System

Published on: March 10, 2020

Application of Biolayer Interferometry (BLI) for Studying Protein-Protein Interactions in Transcription07:18

Application of Biolayer Interferometry (BLI) for Studying Protein-Protein Interactions in Transcription

Published on: July 26, 2019

Related Concept Videos

Flagella and Motility in Bacteria01:18

Flagella and Motility in Bacteria

Flagella are specialized, thread-like structures that extend from a bacteria's cell envelope. They play a crucial role in motility and chemotaxis. Their structural organization and functioning exemplify sophisticated biological engineering, enabling bacterial survival and adaptability in diverse environments.Structure of the FlagellumA bacterial flagellum consists of three key components: the filament, the hook, and basal body. The filament, a long, helical structure composed of repeating...
Gram-negative Bacterial Protein Secretion Systems01:17

Gram-negative Bacterial Protein Secretion Systems

Gram-negative bacteria utilize sophisticated protein secretion systems to transport proteins across their double-membrane envelope into the extracellular environment or host cells. Based on their mechanism of action, these systems are classified into one-step and two-step pathways.One-Step Secretion Systems (Types I, III, IV, and VI)One-step secretion systems bypass the periplasm entirely, forming a continuous channel that spans both the inner and outer membranes:Type I Secretion System (T1SS):...
Gene Regulation in Microbial Communities: Quorum Sensing01:28

Gene Regulation in Microbial Communities: Quorum Sensing

Quorum sensing is a mechanism of bacterial communication that enables coordinated gene expression in response to changes in population density. This facilitates collective behaviors that enhance survival, resource acquisition, and ecological adaptation. This process relies on small signaling molecules called autoinducers that accumulate as bacterial populations grow. When a critical threshold concentration of autoinducers is reached, bacterial cells collectively modify gene expression,...
Gene Regulation During Sporulation01:17

Gene Regulation During Sporulation

Sporulation is a complex developmental process that allows certain Gram-positive bacteria, such as Bacillus subtilis and Clostridium species, to survive extreme environmental conditions. This process is tightly regulated by a series of signaling cascades and transcriptional controls, ensuring the formation of a highly resistant endospore.Sporulation is triggered by unfavorable conditions, such as nutrient depletion, and is governed by a phosphorelay system. One of the sensor kinases, such as...
Bacterial RNA Polymerase00:43

Bacterial RNA Polymerase

Unlike eukaryotes, bacteria use a single RNA Polymerase (RNAP) to transcribe all genes. The different subunits of bacterial RNAPhave distinct functions. The multisubunit structure of the bacterial RNAP helps the enzyme to maintain catalytic function, facilitate assembly, interact with DNA and RNA, and self-regulate its activity.
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...
Bacterial Translocation and Protein Secretion01:26

Bacterial Translocation and Protein Secretion

Bacterial protein secretion involves translocation systems to ensure proteins reach their designated locations, including the plasma membrane, periplasm, outer membrane, or the external environment. These translocation systems are vital for bacterial physiology, supporting processes like membrane assembly, enzymatic activity in the periplasm, and interactions with the external environment. The division of labor between Sec and Tat pathways ensures efficiency in handling proteins with diverse...