ucFabV Requires Functional Reductase Activity to Confer Reduced Triclosan Susceptibility in Escherichia coli

We previously identified the Triclo1 fosmid in a functional metagenomic selection for clones that increased triclosan tolerance in Escherichia coli. The active enzyme encoded by Triclo1 is ucFabV. Although ucFabV is homologous to FabV from other organisms, ucFabV contains substitutions at key positi...

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Bibliographic Details
Published in:	Journal of molecular microbiology and biotechnology Vol. 25; no. 6; p. 394
Main Authors:	Fischer, Taylor L, White, Robert J, Mares, Katherine F K, Molnau, Devin E, Donato, Justin J
Format:	Journal Article
Language:	English
Published:	Switzerland 01-01-2015
Subjects:	Amino Acid Sequence Anti-Infective Agents - pharmacology Drug Resistance, Bacterial Enoyl-(Acyl-Carrier-Protein) Reductase (NADH) - genetics Enoyl-(Acyl-Carrier-Protein) Reductase (NADH) - metabolism Enzyme Activation Escherichia coli - drug effects Escherichia coli - enzymology Escherichia coli - genetics Escherichia coli - metabolism Escherichia coli Proteins - genetics Escherichia coli Proteins - metabolism Fatty Acid Synthase, Type II - genetics Fatty Acid Synthase, Type II - metabolism Mutation Oxidoreductases - metabolism Sequence Homology, Amino Acid Triclosan - pharmacology
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Summary:	We previously identified the Triclo1 fosmid in a functional metagenomic selection for clones that increased triclosan tolerance in Escherichia coli. The active enzyme encoded by Triclo1 is ucFabV. Although ucFabV is homologous to FabV from other organisms, ucFabV contains substitutions at key positions that would predict differences in substrate binding. Therefore, a detailed characterization of ucFabV was conducted to link its biochemical activity to its ability to confer reduced triclosan sensitivity. ucFabV and a catalytic mutant were purified and used to reduce crotonoyl-CoA in vitro. The mutant and wild-type enzymes were introduced into E. coli, and their ability to confer triclosan tolerance as well as suppress a temperature-sensitive mutant of FabI were measured. Purified ucFabV, but not the mutant, reduced crotonoyl-CoA in vitro. The wild-type enzyme confers increased triclosan tolerance when introduced into E. coli, whereas the mutant remained susceptible to triclosan. Additionally, wild-type ucFabV, but not the mutant, functionally replaced FabI within living cells. ucFabV confers increased tolerance through its function as an enoyl-ACP reductase. Furthermore, ucFabV is capable of restoring viability in the presence of compromised FabI, suggesting ucFabV is likely facilitating an alternate step within fatty acid synthesis, bypassing FabI inhibition.
ISSN:	1660-2412
DOI:	10.1159/000441640