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Temperature-dependent regulation of mycolic acid cyclopropanation in saprophytic mycobacteria: Role of the Mycobacterium smegmatis 1351 gene (MSMEG-1351) in cis-cyclopropanation of α-mycolates

Alibaud, L and Alahari, A and Trivelli, X and Ojha, AK and Hatfull, GF and Guerardel, Y and Kremer, L (2010) Temperature-dependent regulation of mycolic acid cyclopropanation in saprophytic mycobacteria: Role of the Mycobacterium smegmatis 1351 gene (MSMEG-1351) in cis-cyclopropanation of α-mycolates. Journal of Biological Chemistry, 285 (28). 21698 - 21707. ISSN 0021-9258

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The cell envelope is a crucial determinant of virulence and drug resistance in Mycobacterium tuberculosis. Several features of pathogenesis and immunomodulation of host responses are attributable to the structural diversity in cell wall lipids, particularly in the mycolic acids. Structural modification of the α-mycolic acid by introduction of cyclopropane rings as catalyzed by the methyltransferase, PcaA, is essential for a lethal, persistent infection and the cording phenotype in M. tuberculosis. Here, we demonstrate the presence of cyclopropanated cell wall mycolates in the nonpathogenic strain Mycobacterium smegmatis and identify MSMEG-1351 as a gene encoding a PcaA homologue. Interestingly, α-mycolic acid cyclopropanation was inducible in cultures grown at 25 °C. The growth temperature modulation of the cyclopropanating activity was determined by high resolution magic angle spinning NMR analyses on whole cells. In parallel, quantitative reverse transcription-PCR analysis showed that MSMEG-1351 gene expression is up-regulated at 25 °C compared with 37 °C. An MSMEG-1351 knock-out strain of M. smegmatis, generated by recombineering, exhibited a deficiency in cyclopropanation of α-mycolates. The functional equivalence of PcaA and MSMEG-1351 was established by cross-complementation in the MSMEG-1351 knock-out mutant and also in a ΔpcaA strain of Mycobacterium bovis BCG. Overexpression of MSMEG-1351 restored the wild-type mycolic acid profile and the cording phenotype in BCG. Although the biological significance of mycolic acid cyclopropanation in nonpathogenic mycobacteria remains unclear, it likely represents a mechanism of adaptation of cell wall structure and composition to cope with environmental factors. © 2010 by The American Society for Biochemistry and Molecular Biology, Inc.


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Item Type: Article
Status: Published
CreatorsEmailPitt UsernameORCID
Alibaud, L
Alahari, A
Trivelli, X
Ojha, AK
Hatfull, GFgfh@pitt.eduGFH
Guerardel, Y
Kremer, L
Date: 9 July 2010
Date Type: Publication
Journal or Publication Title: Journal of Biological Chemistry
Volume: 285
Number: 28
Page Range: 21698 - 21707
DOI or Unique Handle: 10.1074/jbc.m110.125724
Schools and Programs: Dietrich School of Arts and Sciences > Biological Sciences
Refereed: Yes
ISSN: 0021-9258
Related URLs:
MeSH Headings: Cyclopropanes--chemistry; Fatty Acids--metabolism; Gene Expression Regulation, Bacterial; Genetic Complementation Test; Lipids--chemistry; Magnetic Resonance Spectroscopy; Mass Spectrometry--methods; Methyltransferases--metabolism; Mycobacterium bovis--metabolism; Mycobacterium smegmatis--metabolism; Mycolic Acids--chemistry; Mycolic Acids--metabolism; Phenotype; Reverse Transcriptase Polymerase Chain Reaction; Temperature; Up-Regulation
Other ID: NLM PMC2898377
PubMed Central ID: PMC2898377
PubMed ID: 20457615
Date Deposited: 29 Oct 2012 21:19
Last Modified: 28 Sep 2022 13:24


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