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X-Ray Crystallography to Study the Oligomeric State Transition of the Thermotoga maritima M42 Aminopeptidase TmPep1050
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X-Ray Crystallography to Study the Oligomeric State Transition of the Thermotoga maritima M42 Aminopeptidase TmPep1050

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Activator-induced conformational changes regulate division-associated peptidoglycan amidases

Jonathan Cook1, Tyler C Baverstock1, Martin B L McAndrew1

  • 1School of Life Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom.

Proceedings of the National Academy of Sciences of the United States of America
|June 5, 2023
PubMed

Insights

Escherichia coli amidases AmiA and AmiB are essential for cell division. Structural studies reveal how the EnvC protein activates these enzymes by displacing an autoinhibitory helix, enabling peptidoglycan hydrolysis.

Area of Science:

  • Microbiology
  • Structural Biology
  • Biochemistry

Background:

  • AmiA and AmiB are essential peptidoglycan hydrolases in Escherichia coli, crucial for cell division and envelope integrity.
  • Their activity is regulated by the FtsEX-EnvC complex, involving ATP-dependent conformational changes.
  • Activation requires EnvC's LytM domain, which interacts with AmiA and AmiB.

Purpose of the Study:

  • To elucidate the structural basis of AmiA and AmiB autoinhibition and activation.
  • To determine the high-resolution structure of isolated AmiA and the AmiB-EnvC LytM complex.
  • To define the conformational changes mediating enzyme activation.

Main Methods:

  • X-ray crystallography to obtain high-resolution structures of AmiA and the AmiB-EnvC LytM complex.
  • Mutagenesis studies to complement structural findings.

Main Results:

  • The structure of isolated AmiA shows an autoinhibitory helix blocking the active site, similar to AmiB and AmiC.
  • The AmiB-EnvC LytM complex structure reveals that EnvC binding displaces the autoinhibitory helix.
  • This displacement reorganizes the active site, preparing it for peptidoglycan binding and hydrolysis.

Conclusions:

  • The LytM domain of EnvC is the direct activator of AmiA and AmiB amidases.
  • Activation involves a conformational change that releases the autoinhibitory helix.
  • These findings clarify the mechanism of peptidoglycan hydrolase regulation in E. coli cell division.
Keywords:
AmidasesX-ray crystallographybacterial cell divisionpeptidoglycanstructural microbiology

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