This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Singh, V. K.
Right arrow Articles by Wilkinson, B. J.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Singh, V. K.
Right arrow Articles by Wilkinson, B. J.
Agricola
Right arrow Articles by Singh, V. K.
Right arrow Articles by Wilkinson, B. J.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, October 2008, p. 5882-5890, Vol. 74, No. 19
0099-2240/08/$08.00+0     doi:10.1128/AEM.00882-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Insertional Inactivation of Branched-Chain {alpha}-Keto Acid Dehydrogenase in Staphylococcus aureus Leads to Decreased Branched-Chain Membrane Fatty Acid Content and Increased Susceptibility to Certain Stresses{triangledown}

Vineet K. Singh,1* Dipti S. Hattangady,2 Efstathios S. Giotis,2 Atul K. Singh,2 Neal R. Chamberlain,1 Melissa K. Stuart,1 and Brian J. Wilkinson2

Department of Microbiology and Immunology, A.T. Still University of Health Sciences, Kirksville, Missouri 63501,1 Microbiology Group, Department of Biological Sciences, Illinois State University, Normal, Illinois 617902

Received 17 April 2008/ Accepted 25 July 2008

Staphylococcus aureus is a major community and nosocomial pathogen. Its ability to withstand multiple stress conditions and quickly develop resistance to antibiotics complicates the control of staphylococcal infections. Adaptation to lower temperatures is a key for the survival of bacterial species outside the host. Branched-chain {alpha}-keto acid dehydrogenase (BKD) is an enzyme complex that catalyzes the early stages of branched-chain fatty acid (BCFA) production. In this study, BKD was inactivated, resulting in reduced levels of BCFAs in the membrane of S. aureus. Growth of the BKD-inactivated mutant was progressively more impaired than that of wild-type S. aureus with decreasing temperature, to the point that the mutant could not grow at 12°C. The growth of the mutant was markedly stimulated by the inclusion of 2-methylbutyrate in the growth medium at all temperatures tested. 2-Methylbutyrate is a precursor of odd-numbered anteiso fatty acids and bypasses BKD. Interestingly, growth of wild-type S. aureus was also stimulated by including 2-methylbutyrate in the medium, especially at lower temperatures. The anteiso fatty acid content of the BKD-inactivated mutant was restored by the inclusion of 2-methylbutyrate in the medium. Fluorescence polarization measurements indicated that the membrane of the BKD-inactivated mutant was significantly less fluid than that of wild-type S. aureus. Consistent with this result, the mutant showed decreased toluene tolerance that could be increased by the inclusion of 2-methylbutyrate in the medium. The BKD-inactivated mutant was more susceptible to alkaline pH and oxidative stress conditions. Inactivation of the BKD enzyme complex in S. aureus also led to a reduction in adherence of the mutant to eukaryotic cells and its survival in a mouse host. In addition, the mutant offers a tool to study the role of membrane fluidity in the interaction of S. aureus with antimicrobial substances.

* Corresponding author. Mailing address: Department of Microbiology and Immunology, A. T. Still University of Health Sciences, Kirksville, MO 63501. Phone: (660) 626-2474. Fax: (660) 626-2523. E-mail: vsingh{at}atsu.edu

{triangledown} Published ahead of print on 8 August 2008.

Applied and Environmental Microbiology, October 2008, p. 5882-5890, Vol. 74, No. 19
0099-2240/08/$08.00+0     doi:10.1128/AEM.00882-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Keeney, K., Colosi, L., Weber, W., O'Riordan, M. (2009). Generation of Branched-Chain Fatty Acids through Lipoate-Dependent Metabolism Facilitates Intracellular Growth of Listeria monocytogenes. J. Bacteriol. 191: 2187-2196 [Abstract] [Full Text]  


Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»