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A second endolysin gene is fully embedded in-frame with the lysA gene of mycobacteriophage Ms6

Maria João Catalão1, Catarina Milho, Filipa Gil

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

Plos One
|June 23, 2011
PubMed

Insights

Mycobacteriophage Ms6 lysis involves two enzymes, Lysin A and Lysin B. Mutants producing only one form of Lysin A show impaired lysis but retain broad antibacterial activity.

Area of Science:

  • Virology
  • Microbiology
  • Biochemistry

Background:

  • Mycobacteriophages are viruses infecting mycobacteria, crucial for understanding bacterial lysis mechanisms.
  • The Ms6 phage utilizes two key enzymes, Lysin A (LysA) and Lysin B (LysB), for host cell lysis.
  • LysA targets peptidoglycan, while LysB hydrolyzes the mycolylarabinogalactan-peptidoglycan complex.

Purpose of the Study:

  • To investigate the function of the Ms6 phage Lysin A (LysA) and its embedded gene product.
  • To determine the impact of expressing different LysA variants on phage lysis and antibacterial activity.
  • To characterize the enzymatic activity and spectrum of inhibition of LysA variants.

Main Methods:

  • Genetic analysis of the lysA gene and its embedded lysA(241) gene.
  • Construction and characterization of Ms6 phage mutants expressing specific LysA variants.
  • Enzymatic assays to determine peptidoglycan hydrolase activity.
  • Growth inhibition assays against various bacterial species.

Main Results:

  • The lysA gene is essential for Ms6 viability, but mutants expressing only Lysin(384) or Lysin(241) are viable.
  • Both Lysin(384) and Lysin(241) exhibit peptidoglycan hydrolase activity.
  • Phage mutants expressing single LysA variants showed defects in lysis timing, progression, and completion.
  • Both endolysins demonstrated broad growth inhibition against Gram-positive bacteria and mycobacteria.

Conclusions:

  • The Ms6 phage encodes two functional endolysins, Lysin(384) and Lysin(241), with distinct roles in lysis.
  • While both endolysins possess antibacterial properties, their coordinated action is necessary for efficient host cell lysis.
  • These findings contribute to understanding phage-mediated lysis and offer potential for novel antibacterial agents.

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