JB
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
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 Vilchèze, C.
Right arrow Articles by Jacobs, W. R.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Vilchèze, C.
Right arrow Articles by Jacobs, W. R., Jr.

 Previous Article  |  Next Article 

Journal of Bacteriology, July 2000, p. 4059-4067, Vol. 182, No. 14
0021-9193/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.

Inactivation of the inhA-Encoded Fatty Acid Synthase II (FASII) Enoyl-Acyl Carrier Protein Reductase Induces Accumulation of the FASI End Products and Cell Lysis of Mycobacterium smegmatis

Catherine Vilchèze,1 Hector R. Morbidoni,1 Torin R. Weisbrod,1 Hiroyuki Iwamoto,2 Mack Kuo,2 James C. Sacchettini,2 and William R. Jacobs Jr.1,*

Howard Hughes Medical Institute, Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461,1 and Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 778432

Received 10 February 2000/Accepted 19 April 2000

The mechanism of action of isoniazid (INH), a first-line antituberculosis drug, is complex, as mutations in at least five different genes (katG, inhA, ahpC, kasA, and ndh) have been found to correlate with isoniazid resistance. Despite this complexity, a preponderance of evidence implicates inhA, which codes for an enoyl-acyl carrier protein reductase of the fatty acid synthase II (FASII), as the primary target of INH. However, INH treatment of Mycobacterium tuberculosis causes the accumulation of hexacosanoic acid (C26:0), a result unexpected for the blocking of an enoyl-reductase. To test whether inactivation of InhA is identical to INH treatment of mycobacteria, we isolated a temperature-sensitive mutation in the inhA gene of Mycobacterium smegmatis that rendered InhA inactive at 42°C. Thermal inactivation of InhA in M. smegmatis resulted in the inhibition of mycolic acid biosynthesis, a decrease in hexadecanoic acid (C16:0) and a concomitant increase of tetracosanoic acid (C24:0) in a manner equivalent to that seen in INH-treated cells. Similarly, INH treatment of Mycobacterium bovis BCG caused an inhibition of mycolic acid biosynthesis, a decrease in C16:0, and a concomitant accumulation of C26:0. Moreover, the InhA-inactivated cells, like INH-treated cells, underwent a drastic morphological change, leading to cell lysis. These data show that InhA inactivation, alone, is sufficient to induce the accumulation of saturated fatty acids, cell wall alterations, and cell lysis and are consistent with InhA being a primary target of INH.

* Corresponding author. Mailing address: Howard Hughes Medical Institute, Department of Microbiology and Immunology, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, NY 10461. Phone: (718) 430-2888. Fax: (718) 518-0366. E-mail: jacobs{at}aecom.yu.edu.

Journal of Bacteriology, July 2000, p. 4059-4067, Vol. 182, No. 14
0021-9193/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.


This article has been cited by other articles:



Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
Appl. Environ. Microbiol. Infect. Immun. Eukaryot. Cell
Mol. Cell. Biol. J. Virol. Microbiol. Mol. Biol. Rev.
ALL ASM JOURNALS

Copyright © 2000 by the American Society for Microbiology. All rights reserved.