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Updated: Jan 2, 2026

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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Crystal structure of mature myroilysin and implication for its activation mechanism

Tingting Ran1, Weidong Li1, Bo Sun2

  • 1Department of Microbiology, College of Life Sciences, Nanjing Agricultural University, 210095 Nanjing, China.

International Journal of Biological Macromolecules
|December 1, 2019
PubMed

Insights

Myroilysin, a bacterial metalloprotease, reveals its activation mechanism and structural secrets. Key residues Tyr208 and Glu151 are crucial for its activity and stability.

Area of Science:

  • Biochemistry
  • Structural Biology
  • Enzymology

Background:

  • Myroilysin is a novel bacterial M12A metalloprotease with a unique "cysteine switch" activation and "cap" structure.
  • The activation mechanism of pro-myroilysin remained largely unelucidated prior to this study.

Purpose of the Study:

  • To determine the structure of mature myroilysin and elucidate its activation mechanism.
  • To investigate the functional roles of key residues Tyr208 and Glu151 in myroilysin activity and stability.

Main Methods:

  • Obtained mature myroilysin by trypsin treatment of pro-myroilysin for structure determination.
  • Performed site-directed mutagenesis (Tyr208 and Glu151) and analyzed proteolytic activity and thermostability.
  • Conducted structural comparisons between myroilysin and astacin.

Main Results:

  • Determined the crystal structure of mature myroilysin, revealing zinc ion coordination by His, water, and Tyr208 within the SIMHY motif.
  • Observed significant conformational changes upon activation, including cap movement and N-terminus burial, with Glu151 forming a salt bridge with Gly38.
  • Mutational analysis demonstrated Tyr208 is vital for activity, while Glu151 is critical for both catalysis and structural stability, with mutant E151A showing reduced activity and thermostability.
  • Structural comparison highlighted differences between myroilysin and astacin.

Conclusions:

  • The study provides novel insights into the activation mechanism of myroilysin, involving conformational changes and the role of the "cap" structure.
  • Tyr208 and Glu151 are identified as crucial residues for myroilysin's catalytic function and structural integrity.
  • Biochemical and structural data offer a foundation for understanding M12A metalloprotease activation and function.
Keywords:
Activation mechanismCrystal structureM12 family proteaseMyroilysin

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