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The membrane localization domains of two distinct bacterial toxins form a 4-helix-bundle in solution

Grant S Hisao1, Michael C Brothers1, Mengfei Ho2

  • 1Department of Chemistry, University of Illinois at Urbana-Champaign, Illinois.

Protein Science : a Publication of the Protein Society
|December 16, 2016
PubMed

Insights

The membrane localization domain (MLD) in Pasteurella multocida toxin and Vibrio vulnificus MARTX toxin adopts a 4-helix-bundle structure in solution, confirmed by NMR.

Area of Science:

  • Structural Biology
  • Molecular Biology
  • Toxinology

Background:

  • The membrane localization domain (MLD) was initially identified as a 4-helix-bundle motif in Pasteurella multocida toxin (PMT).
  • This motif is conserved in crystal structures of several clostridial glycosylating toxins.
  • The Ras/Rap1-specific endopeptidase (RRSP) module of Vibrio vulnificus MARTX toxin shares homology with PMT domains, including a potential MLD.

Purpose of the Study:

  • To determine the solution structure of the MLDs in PMT and RRSP.
  • To investigate the structural conformation of MLDs in different bacterial toxins.

Main Methods:

  • Solution state Nuclear Magnetic Resonance (NMR) spectroscopy was employed.
  • Structural analysis of MLDs from PMT and RRSP.

Main Results:

  • The solution structure of the MLDs in both PMT and RRSP was successfully determined.
  • Both MLDs were found to adopt a 4-helix-bundle structure in solution.

Conclusions:

  • The MLDs in PMT and RRSP exhibit a conserved 4-helix-bundle structure in solution.
  • This structural similarity suggests a common mechanism for membrane localization across different bacterial toxins.
Keywords:
4-helix-bundlePasteurella multocidaVibrio vulnificusbacterial toxinmembrane localization domainssolution NMR spectroscopy

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