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Enrichment of Native and Recombinant Extracellular Vesicles of Mycobacteria
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The mycobacteriophage Ms6 encodes a chaperone-like protein involved in the endolysin delivery to the peptidoglycan

Maria João Catalão1, Filipa Gil, José Moniz-Pereira

  • 1Centro de Patogénese Molecular, Unidade dos Retrovirus e Infecções Associadas, Faculdade de Farmácia, Universidade de Lisboa, Lisboa, Portugal.

Molecular Microbiology
|June 16, 2010
PubMed

Insights

Mycobacteriophage Ms6 lysis involves endolysin (LysA) delivery. The accessory protein Gp1 acts like a chaperone, aiding LysA transport to the murein layer independently of the holin system for efficient host cell lysis.

Area of Science:

  • Molecular biology
  • Microbiology
  • Virology

Background:

  • Double-stranded DNA phages, including mycobacteriophage Ms6, typically employ a holin-endolysin system for host cell lysis.
  • Ms6 encodes additional accessory lysis proteins beyond the canonical holin and endolysin (LysA) genes.

Purpose of the Study:

  • To investigate the lysis function of the accessory protein Gp1, encoded by the gp1 gene in mycobacteriophage Ms6.
  • To elucidate the mechanism by which Gp1 contributes to host cell lysis, particularly its interaction with LysA.

Main Methods:

  • Coexpression of LysA and Gp1 in Escherichia coli to assess lysis in the absence of Ms6 holin.
  • Analysis of Gp1's characteristics to determine its protein class, including potential chaperone activity.
  • PhoA fusions in Mycobacterium smegmatis to track LysA export in the presence of Gp1.
  • Construction and analysis of Ms6 gp1 deletion mutants to evaluate lysis defects.

Main Results:

  • Coexpression of LysA and Gp1 induced lysis in E. coli without Ms6 holin, suggesting a holin-independent role for Gp1.
  • Gp1 exhibits characteristics of molecular chaperones and directly interacts with LysA, facilitating its delivery to the target site.
  • In M. smegmatis, Gp1 promotes the export of LysA to the extracytoplasmic environment, and gp1 deletion impairs efficient host lysis.

Conclusions:

  • Gp1 functions as a chaperone-like protein that assists in the delivery of Ms6 endolysin (LysA) to the murein layer.
  • This Gp1-mediated delivery mechanism operates independently of the holin protein, representing a novel aspect of phage lysis.
  • Gp1 is essential for efficient mycobacteriophage Ms6-mediated lysis of its host, Mycobacterium smegmatis.

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