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In Situ Monitoring of Transiently Formed Molecular Chaperone Assemblies in Bacteria, Yeast, and Human Cells
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A new means to identify type 3 secreted effectors: functionally interchangeable class IB chaperones recognize a

Sonia C P Costa1, Alexa M Schmitz, Fathima F Jahufar

  • 1Division of Infectious Diseases, Department of Medicine (Microbiology and Molecular Genetics), Massachusetts General Hospital and Harvard Medical School, Cambridge, Massachusetts, USA.

Mbio
|February 16, 2012
PubMed
Summary

Class IB chaperones from Gram-negative bacteria bind a conserved effector sequence, enabling identification of new bacterial secretion system substrates. These chaperones are interchangeable across species, offering potential targets for novel antibiotic development.

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Published on: June 7, 2018

Area of Science:

  • Microbiology
  • Molecular Biology
  • Bacterial Pathogenesis

Background:

  • Gram-negative bacteria use type 3 secretion systems (T3SS) to inject effector proteins into host cells.
  • Identifying these effectors is crucial for understanding bacterial pathogenesis, but many require chaperones for secretion, complicating bioinformatic identification.
  • Class IB chaperones are known to assist in the secretion of T3SS effectors.

Purpose of the Study:

  • To investigate the substrate specificity of class IB chaperones.
  • To determine if class IB chaperones are functionally interchangeable across different bacterial species.
  • To identify a conserved sequence recognized by class IB chaperones for effector identification.

Main Methods:

  • Utilized a protein interaction platform assay to study chaperone-effector binding.
  • Tested the functional interchangeability of class IB homologs from seven different bacterial species.
  • Developed and applied a pattern search algorithm based on a newly identified conserved sequence.

Main Results:

  • Class IB chaperones bind specific effectors, including those from other bacterial species.
  • Class IB chaperones from seven species demonstrated functional interchangeability in mediating effector translocation.
  • A conserved chaperone-binding domain (CCBD) sequence, [(LMIF)(1)XXX(IV)(5)XX(IV)(8)X(N)(10)], was identified as the recognition motif.
  • The CCBD sequence facilitated the identification of novel effectors from the endosymbiont Sodalis glossinidius.

Conclusions:

  • Class IB chaperones recognize a specific conserved sequence (CCBD) rather than being promiscuous.
  • The functional interchangeability of class IB chaperones suggests broad applicability in studying T3SS.
  • The identified CCBD sequence provides a novel bioinformatic tool for discovering new T3SS effectors.
  • Targeting chaperone-effector interactions could lead to new therapeutic strategies against Gram-negative pathogens.