Identification of a novel peptidoglycan hydrolase CwlM in Mycobacterium tuberculosis.
Mycobacterium tuberculosis is a major global pathogen whose threat has increased with the emergence of multidrug-resistant strains. The cell wall of M. tuberculosis is thick, rigid, and hydrophobic, which serves to protect the organism from the environment and makes it highly impermeable to conventional antimicrobial agents. There is little known about cell wall autolysins (also referred to as peptidoglycan hydrolases) of mycobacteria. We identified an open reading frame (Rv3915) in the M. tuberculosis genome designated cwlM that appeared consistent with a peptidoglycan hydrolase. The 1218-bp gene was amplified by PCR, cloned and expressed in E. coli strain HMS174(DE-3), and its gene product, a 47-kDa recombinant protein, was purified and partially characterized. Purified CwlM was able to lyse whole mycobacteria, release peptidoglycan from the cell wall of Micrococcus luteus and Mycobacterium smegmatis, and cleave N-acetylmuramoyl-L-alanyl-D-isoglutamine, releasing free N-acetylmuramic acid. These results indicate that CwlM is a novel autolysin and identify cwlM as the first, to our knowledge, autolysin gene identified and cloned from M. tuberculosis. CwlM offers a new target for a unique class of drugs that could alter the permeability of the mycobacterial cell wall and enhance the effectiveness of treatments for tuberculosis.
Deng
Lingyi Lynn
LL
Department of Medicine, Boston University School of Medicine, Research Service, VA Boston Healthcare System, 150 S. Huntington Ave., Boston, MA 02130, USA. lynndeng@bu.edu
Humphries
Donald E
DE
Arbeit
Robert D
RD
Carlton
Laura E
LE
Smole
Sandra C
SC
Carroll
J David
JD
D000119:Acetylmuramyl-Alanyl-Isoglutamine / Q000378:metabolism; D001483:Base Sequence; D002473:Cell Wall / Q000201:enzymology / Q000378:metabolism; D003001:Cloning, Molecular; D019295:Computational Biology; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D016680:Genome, Bacterial; D007477:Ions / Q000378:metabolism / Q000494:pharmacology; D008969:Molecular Sequence Data; D009112:Muramic Acids / Q000378:metabolism; D009169:Mycobacterium tuberculosis / Q000201:enzymology* / Q000235:genetics; D009238:N-Acetylmuramoyl-L-alanine Amidase / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D016366:Open Reading Frames / Q000235:genetics; D010457:Peptidoglycan / Q000378:metabolism
D007477:Ions; D009112:Muramic Acids; D010457:Peptidoglycan; C031651:N-acetylmuramic acid; D000119:Acetylmuramyl-Alanyl-Isoglutamine; D009238:N-Acetylmuramoyl-L-alanine Amidase