Document Detail

Structure-activity studies of the inhibition of FabI, the enoyl reductase from Escherichia coli, by triclosan: kinetic analysis of mutant FabIs.
MedLine Citation:
PMID:  12693936     Owner:  NLM     Status:  MEDLINE    
Triclosan, a common antibacterial additive used in consumer products, is an inhibitor of FabI, the enoyl reductase enzyme from type II bacterial fatty acid biosynthesis. In agreement with previous studies [Ward, W. H., Holdgate, G. A., Rowsell, S., McLean, E. G., Pauptit, R. A., Clayton, E., Nichols, W. W., Colls, J. G., Minshull, C. A., Jude, D. A., Mistry, A., Timms, D., Camble, R., Hales, N. J., Britton, C. J., and Taylor, I. W. (1999) Biochemistry 38, 12514-12525], we report here that triclosan is a slow, reversible, tight binding inhibitor of the FabI from Escherichia coli. Triclosan binds preferentially to the E.NAD(+) form of the wild-type enzyme with a K(1) value of 23 pM. In agreement with genetic selection experiments [McMurry, L. M., Oethinger, M., and Levy, S. B. (1998) Nature 394, 531-532], the affinity of triclosan for the FabI mutants G93V, M159T, and F203L is substantially reduced, binding preferentially to the E.NAD(+) forms of G93V, M159T, and F203L with K(1) values of 0.2 microM, 4 nM, and 0.9 nM, respectively. Triclosan binding to the E.NADH form of F203L can also be detected and is defined by a K(2) value of 51 nM. We have also characterized the Y156F and A197M mutants to compare and contrast the binding of triclosan to InhA, the homologous enoyl reductase from Mycobacterium tuberculosis. As observed for InhA, Y156F FabI has a decreased affinity for triclosan and the inhibitor binds to both E.NAD(+) and E.NADH forms of the enzyme with K(1) and K(2) values of 3 and 30 nM, respectively. The replacement of A197 with Met has no impact on triclosan affinity, indicating that differences in the sequence of the conserved active site loop cannot explain the 10000-fold difference in affinities of FabI and InhA for triclosan.
Sharada Sivaraman; Jacque Zwahlen; Alasdair F Bell; Lizbeth Hedstrom; Peter J Tonge
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Biochemistry     Volume:  42     ISSN:  0006-2960     ISO Abbreviation:  Biochemistry     Publication Date:  2003 Apr 
Date Detail:
Created Date:  2003-04-15     Completed Date:  2003-05-14     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0370623     Medline TA:  Biochemistry     Country:  United States    
Other Details:
Languages:  eng     Pagination:  4406-13     Citation Subset:  IM    
Department of Chemistry, State University of New York at Stony Brook, 11794-3400, USA.
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MeSH Terms
Amino Acid Substitution
Catalytic Domain
Enoyl-(Acyl-Carrier-Protein) Reductase (NADH)
Escherichia coli / enzymology*
Escherichia coli Proteins
Oxidoreductases / chemistry*,  genetics,  metabolism*
Structure-Activity Relationship
Triclosan / metabolism
Grant Support
Reg. No./Substance:
0/Escherichia coli Proteins; 3380-34-5/Triclosan; EC 1.-/Oxidoreductases; EC Reductase (NADH); EC protein, E coli

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