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The hydrolase LpqI primes mycobacterial peptidoglycan recycling

Patrick J Moynihan1, Ian T Cadby2, Natacha Veerapen2

  • 1Institute of Microbiology and Infection, School of Biological Sciences, University of Birmingham, Birmingham, B15 2TT, UK. p.j.moynihan@bham.ac.uk.

Nature Communications
|June 16, 2019
PubMed

Insights

Pathogenic mycobacteria, including Mycobacterium tuberculosis, can recycle peptidoglycan (PG) components. The gene lpqI encodes an essential enzyme for this PG-derived amino sugar recycling pathway.

Area of Science:

  • Microbiology
  • Cell Biology
  • Biochemistry

Background:

  • Bacterial growth and division necessitate cell wall remodeling and cleavage.
  • This process releases peptidoglycan (PG) fragments called muropeptides, which are recycled by many bacteria.
  • Muropeptides serve as signals for cell wall damage in bacteria and infection detection in hosts.

Purpose of the Study:

  • To investigate whether pathogenic mycobacteria, specifically Mycobacterium tuberculosis and Mycobacterium bovis BCG, recycle their peptidoglycan.
  • To identify the molecular mechanisms underlying peptidoglycan recycling in mycobacteria.

Main Methods:

  • Genetic analysis of the mycobacterial gene lpqI.
  • Biochemical characterization of the enzyme encoded by lpqI.
  • Investigation of peptidoglycan-derived amino sugar recycling pathways.

Main Results:

  • Mycobacterium tuberculosis and Mycobacterium bovis BCG were shown to recycle PG components.
  • The gene lpqI encodes a functional NagZ β-N-acetylglucosaminidase.
  • This enzyme is essential for an atypical pathway of PG-derived amino sugar recycling.

Conclusions:

  • Contrary to previous assumptions, pathogenic mycobacteria do recycle peptidoglycan.
  • The lpqI gene and its encoded NagZ enzyme are critical for this recycling process.
  • This study provides foundational insights into mycobacterial peptidoglycan recycling mechanisms.

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