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Applying an Inducible Expression System to Study Interference of Bacterial Virulence Factors with Intracellular Signaling
08:51

Applying an Inducible Expression System to Study Interference of Bacterial Virulence Factors with Intracellular Signaling

Published on: June 25, 2015

Targeted sigma factor turnover inserts negative control into a positive feedback loop.

Timothy J Donohue1

  • 1University of Wisconsin-Madison, Bacteriology Department, Madison, WI 53706, USA. tdonohue@bact.wisc.edu

Molecular Microbiology
|August 18, 2009
PubMed
Summary
This summary is machine-generated.

Streptomyces coelicolor

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Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • Group IV alternative sigma factors regulate gene expression in response to environmental and stress signals.
  • In Streptomyces coelicolor, sigma(R) (SigR) activity is modulated by cytoplasmic disulfide bond redox state.
  • SigR activation leads to the expression of genes that reduce cytoplasmic disulfide bonds.

Discussion:

  • Kim and co-workers investigate the positive and negative regulation of SigR activity.
  • A transcript from the sigRrsrA p2 promoter encodes a higher molecular weight sigma(R) protein (SigR').
  • SigR' undergoes rapid proteolysis by the ClpP1/P2 protease system, unlike the smaller SigR found in uninduced cells.

Key Insights:

  • A novel positive control mechanism involves the synthesis of SigR'.
  • A negative control mechanism is identified through the selective turnover of SigR' by ClpP1/P2 protease.
  • The ClpP1/P2 protease subunit genes are part of the SigR regulon.

Outlook:

  • The newly identified regulatory circuit of SigR' synthesis and turnover provides new insights into sigma factor regulation.
  • These regulatory mechanisms are predicted to be conserved in other Group IV sigma factor family members.