Identification of a Membrane Protein Required for Lipomannan Maturation and Lipoarabinomannan Synthesis in Corynebacterineae.
Mycobacterium tuberculosisand related Corynebacterineae synthesize a family of lipomannans (LM) and lipoarabinomannans (LAM) that are abundant components of the multilaminate cell wall and essential virulence factors in pathogenic species. Here we describe a new membrane protein, highly conserved in all Corynebacterineae, that is required for synthesis of full-length LM and LAM. Deletion of theCorynebacterium glutamicum NCgl2760gene resulted in a complete loss of mature LM/LAM and the appearance of a truncated LM (t-LM). Complementation of the mutant with theNCgl2760gene fully restored LM/LAM synthesis. Structural studies, including monosaccharide analysis, methylation linkage analysis, and mass spectrometry of native LM species, indicated that the ΔNCgl2760t-LM comprised a series of short LM species (8-27 residues long) containing an α1-6-linked mannose backbone with greatly reduced α1-2-mannose side chains and no arabinose caps. The structure of the ΔNCgl2760t-LM was similar to that of the t-LM produced by aC. glutamicummutant lacking themptAgene, encoding a membrane α1-6-mannosyltransferase involved in extending the α1-6-mannan backbone of LM intermediates. Interestingly, NCgl2760 lacks any motifs or homology to other proteins of known function. Attempts to delete theNCgl2760orthologue inMycobacterium smegmatiswere unsuccessful, consistent with previous studies indicating that theM. tuberculosisorthologue,Rv0227c, is an essential gene. Together, these data suggest that NCgl2760/Rv0227c plays a critical role in the elongation of the mannan backbone of mycobacterial and corynebacterial LM, further highlighting the complexity of lipoglycan pathways of Corynebacterineae.
From the Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800 and.
Tamaryn J
TJ
Cashmore
the Department of Biochemistry and Molecular Biology, Bio21 Institute of Molecular Sciences and Biotechnology, University of Melbourne, Parkville, Victoria 3010, Australia.
Stephan
S
Klatt
the Department of Biochemistry and Molecular Biology, Bio21 Institute of Molecular Sciences and Biotechnology, University of Melbourne, Parkville, Victoria 3010, Australia.
Yoshiki
Y
Yamaryo-Botte
From the Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800 and.
Rajini
R
Brammananth
From the Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800 and.
Arek K
AK
Rainczuk
the Department of Biochemistry and Molecular Biology, Bio21 Institute of Molecular Sciences and Biotechnology, University of Melbourne, Parkville, Victoria 3010, Australia.
Malcolm J
MJ
McConville
From the Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800 and paul.crellin@monash.edu.
Paul K
PK
Crellin
From the Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800 and.
Ross L
RL
Coppel
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D053898:Biosynthetic Pathways; D002473:Cell Wall / Q000235:genetics / Q000378:metabolism; D048230:Corynebacterium glutamicum / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D008070:Lipopolysaccharides / Q000378:metabolism*
D001426:Bacterial Proteins; D008070:Lipopolysaccharides; C050016:lipoarabinomannan; C064351:lipomannan
Corynebacterium glutamicum; Mycobacterium tuberculosis; cell wall; glycolipid; lipid synthesis; lipoarabinomannan; lipomannan; membrane protein