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Updated: Jun 5, 2025

Quantifying the Cytotoxicity of Staphylococcus aureus Against Human Polymorphonuclear Leukocytes
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Quantifying the Cytotoxicity of Staphylococcus aureus Against Human Polymorphonuclear Leukocytes

Published on: January 3, 2020

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Structural Basis for the Essential Role of Ca2+ in the Lytic Activity of Staphylococcus aureus PlyGRCS Endolysin

Gopinatha Krishnappa1,2,3, Harshitha Nagaraj1, Harshavardini Bakthavatsalam SureshKumar1

  • 1Department of Biophysics, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, India.

Proteins
|December 11, 2024
PubMed

Insights

Bacteriophage endolysins like PlyGRCS show potential against Staphylococcus aureus infections. Key residues are crucial for its lytic activity against methicillin-resistant Staphylococcus aureus (MRSA), especially in the presence of Ca2+ ions.

Area of Science:

  • Microbiology
  • Structural Biology
  • Biochemistry

Background:

  • Staphylococcus aureus infections range from mild to life-threatening.
  • Bacteriophage endolysins are promising biotherapeutics against antibiotic-resistant bacteria.
  • PlyGRCS is an S. aureus-derived endolysin with catalytic and cell-wall binding domains.

Purpose of the Study:

  • To investigate the structural and functional roles of Ca2+ ions and specific residues in PlyGRCS activity.
  • To understand the mechanism of PlyGRCS bacteriolytic efficacy against MRSA.

Main Methods:

  • Crystal structure determination of PlyGRCS in the absence of Ca2+.
  • Site-directed mutagenesis of key residues in the catalytic and Ca2+ binding sites.
  • Antimicrobial assays to evaluate lytic activity against MRSA.

Main Results:

  • The crystal structure revealed significant conformational changes in the Ca2+ binding site without Ca2+.
  • Ca2+-deficient PlyGRCS and specific mutants showed reduced lytic activity.
  • Identified critical functional residues essential for PlyGRCS efficacy against MRSA.

Conclusions:

  • Ca2+ ions and specific residues are vital for PlyGRCS's catalytic function and bacteriolytic activity.
  • Structural insights inform the development of endolysins as therapeutics against MRSA infections.
Keywords:
Staphylococcus aureusPlyGRCScalciumcrystal structureendolysinlytic activitymicrobial assaysmutants

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