The Mycobacterium tuberculosis cmaA2 gene encodes a mycolic acid trans-cyclopropane synthetase. Academic Article uri icon

Overview

abstract

  • Infection with Mycobacterium tuberculosis remains a major global health emergency. Although detailed understanding of the molecular events of M. tuberculosis pathogenesis is still limited, recent genetic analyses have implicated specific lipids of the cell envelope as important effectors in M. tuberculosis pathogenesis. We have shown that pcaA, a novel member of a family of M. tuberculosis S-adenosyl methionine (SAM)-dependent methyl transferases, is required for alpha-mycolic acid cyclopropanation and lethal chronic persistent M. tuberculosis infection. To examine the apparent redundancy between pcaA and cmaA2, another cyclopropane synthetase of M. tuberculosis thought to be involved in alpha-mycolate synthesis, we have disrupted the cmaA2 gene in virulent M. tuberculosis by specialized transduction. Inactivation of cmaA2 causes accumulation of unsaturated derivatives of both the methoxy- and ketomycolates. Analysis by proton NMR indicates that the mycolic acids of the cmaA2 mutant lack trans-cyclopropane rings but are otherwise intact with respect to cyclopropane and methyl branch content. Thus, cmaA2 is required for the synthesis of the trans cyclopropane rings of both the methoxymycolates and ketomycolates. These results define cmaA2 as a trans-cyclopropane synthetase and expand our knowledge of the substrate specificity of a large family of highly homologous mycolic acid methyl transferases recently shown to be critical to M. tuberculosis pathogenesis.

publication date

  • November 22, 2000

Research

keywords

  • Bacterial Proteins
  • Methyltransferases
  • Mycobacterium tuberculosis

Identity

Scopus Document Identifier

  • 0035910583

PubMed ID

  • 11092877

Additional Document Info

volume

  • 276

issue

  • 3