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The Ms6 Mycolyl-Arabinogalactan Esterase LysB is Essential for an Efficient Mycobacteriophage-Induced Lysis

Adriano M Gigante1, Cheri M Hampton2, Rebecca S Dillard3

  • 1Research Institute for Medicines (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa, Lisbon, 1649-003, Portugal. amsgigante@ff.ulisboa.pt.

Viruses
|November 18, 2017
PubMed

Insights

Mycobacteriophage LysB protein is crucial for efficient host lysis and phage release. A mutant lacking LysB showed incomplete lysis and retained phage particles within Mycobacterium smegmatis cells.

Area of Science:

  • Bacteriophage biology
  • Microbial genetics
  • Cell envelope structure

Background:

  • Bacteriophages utilize endolysins, holins, and spanins for host cell lysis.
  • Mycobacteriophages possess a unique lytic cassette gene encoding LysB, a mycolyl-arabinogalactan esterase.
  • The complex mycobacterial cell envelope necessitates specialized lysis mechanisms.

Purpose of the Study:

  • To investigate the role of LysB in the lysis process of mycobacteriophage Ms6 infecting Mycobacterium smegmatis.
  • To elucidate the function of LysB in phage particle release and host cell envelope disruption.

Main Methods:

  • Construction and analysis of an Ms6 mutant deficient in LysB.
  • Cryo-electron microscopy and tomography to visualize lysis phenotypes.
  • Comparative analysis of wild-type Ms6 and LysB mutant infected cells.

Main Results:

  • Ms6 LysB is essential for efficient lysis and complete phage particle release.
  • LysB-deficient mutants exhibit incomplete lysis, retaining phage particles intracellularly.
  • Cryo-electron microscopy confirmed delayed and incomplete lysis in the absence of LysB.

Conclusions:

  • Ms6 LysB plays a critical role in the final stages of mycobacterial lysis, analogous to spanins.
  • LysB facilitates efficient release of progeny phage particles from infected Mycobacterium smegmatis.
  • This study highlights the importance of LysB in overcoming the complex mycobacterial cell envelope during phage infection.
Keywords:
LysBMs6bacteriophage lysiscryo-electron microscopymycobacteriamycobacteriophagespanins

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