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Mechanistic and structural insights into the proteolytic activation of Vibrio cholerae MARTX toxin

Aimee Shen1, Patrick J Lupardus, Victoria E Albrow

  • 1Department of Pathology, and Howard Hughes Medical Institute, Stanford School of Medicine, Stanford,California, USA.

Nature Chemical Biology
|May 26, 2009
PubMed

Insights

MARTX toxins, crucial for Vibrio virulence, are better understood through their cysteine protease domain (CPD). New inhibitors and structural data reveal substrate specificity, aiding antitoxin strategy development.

Area of Science:

  • Microbiology
  • Structural Biology
  • Biochemistry

Background:

  • MARTX toxins are key virulence factors in Vibrio species, featuring a cysteine protease domain (CPD).
  • The CPD proteolytically activates MARTX toxins, but its substrate recognition and processing mechanisms remain unclear.
  • Recent studies revealed an allosteric activation mechanism for the CPD.

Purpose of the Study:

  • To elucidate the substrate recognition and processing mechanisms of the MARTX toxin's CPD.
  • To identify small-molecule inhibitors of the CPD.
  • To understand the evolutionary relationship between the CPD and caspase proteases.

Main Methods:

  • Biochemical assays and mutational studies to analyze toxin processing.
  • X-ray crystallography to determine the structure of the CPD bound to an inhibitor.
  • Comparative analysis with clan CD caspase proteases.

Main Results:

  • Interdomain cleavage of MARTXVc enhances effector domain function.
  • The first small-molecule inhibitors of the MARTX CPD were identified.
  • The 2.35-A crystal structure of the CPD-inhibitor complex revealed the molecular basis of substrate specificity.
  • An evolutionary link between the CPD and caspase proteases was established.

Conclusions:

  • Understanding MARTX CPD substrate specificity is key to its function.
  • The identified inhibitors and structural insights provide a foundation for new antitoxin strategies.
  • These findings offer valuable insights into bacterial pathogenesis and potential therapeutic interventions.

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