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Cell Rep. 2018 Oct 2;25(1):57-67.e5. doi: 10.1016/j.celrep.2018.09.004.

Two Faces of CwlM, an Essential PknB Substrate, in Mycobacterium tuberculosis.

Author information

1
Leicester Tuberculosis Research Group, Department of Infection, Immunity and Inflammation, University of Leicester, Leicester LE1 9HN, UK.
2
Department of Biosciences, University of Milan, Milan 20133, Italy.
3
Leicester Tuberculosis Research Group, Department of Infection, Immunity and Inflammation, University of Leicester, Leicester LE1 9HN, UK; Biology Department, College of Science, University of Al-Qadisiyah, Al-Diwaniyah 58002, Iraq.
4
Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4AX, UK.
5
Electron Microscopy Facility, Core Biotechnology Services, University of Leicester, Leicester LE1 7RH, UK.
6
Protein Nucleic Acid Laboratory, University of Leicester, Leicester LE1 7RH, UK.
7
School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
8
Leicester Tuberculosis Research Group, Department of Infection, Immunity and Inflammation, University of Leicester, Leicester LE1 9HN, UK; The Leicester Institute of Structural and Chemical Biology, Henry Wellcome Building, University of Leicester, Lancaster Road, Leicester LE1 7HB, UK.
9
Centre de Biochimie Structurale, CNRS, INSERM, University of Montpellier, Montpellier 34090, France.
10
Gemini Biosciences, Liverpool Science Park, Liverpool L3 5TF, UK.
11
Leicester Tuberculosis Research Group, Department of Infection, Immunity and Inflammation, University of Leicester, Leicester LE1 9HN, UK. Electronic address: gvm4@le.ac.uk.

Abstract

Tuberculosis claims >1 million lives annually, and its causative agent Mycobacterium tuberculosis is a highly successful pathogen. Protein kinase B (PknB) is reported to be critical for mycobacterial growth. Here, we demonstrate that PknB-depleted M. tuberculosis can replicate normally and can synthesize peptidoglycan in an osmoprotective medium. Comparative phosphoproteomics of PknB-producing and PknB-depleted mycobacteria identify CwlM, an essential regulator of peptidoglycan synthesis, as a major PknB substrate. Our complementation studies of a cwlM mutant of M. tuberculosis support CwlM phosphorylation as a likely molecular basis for PknB being essential for mycobacterial growth. We demonstrate that growing mycobacteria produce two forms of CwlM: a non-phosphorylated membrane-associated form and a PknB-phosphorylated cytoplasmic form. Furthermore, we show that the partner proteins for the phosphorylated and non-phosphorylated forms of CwlM are FhaA, a fork head-associated domain protein, and MurJ, a proposed lipid II flippase, respectively. From our results, we propose a model in which CwlM potentially regulates both the biosynthesis of peptidoglycan precursors and their transport across the cytoplasmic membrane.

KEYWORDS:

CwlM; MurJ; Mycobacterium tuberculosis; cellular localization; peptidoglycan; phosphoproteomics; protein kinase B; serine/threonine protein kinase

PMID:
30282038
PMCID:
PMC6180346
DOI:
10.1016/j.celrep.2018.09.004
[Indexed for MEDLINE]
Free PMC Article

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