title: A new member of the Escherichia coli fad regulon: transcriptional regulation of fadM (ybaW).
abstract: Recently, Nie and coworkers (L. Nie, Y. Ren, A. Janakiraman, S. Smith, and H. Schulz, Biochemistry 47:9618-9626, 2008) reported a new Escherichia coli thioesterase encoded by the ybaW gene that cleaves the thioester bonds of inhibitory acyl-coenzyme A (CoA) by-products generated during beta-oxidation of certain unsaturated fatty acids. These authors suggested that ybaW expression might be regulated by FadR, the repressor of the fad (fatty acid degradation) regulon. We report mapping of the ybaW promoter and show that ybaW transcription responded to FadR in vivo. Moreover, purified FadR bound to a DNA sequence similar to the canonical FadR binding site located upstream of the ybaW coding sequence and was released from the promoter upon the addition of long-chain acyl-CoA thioesters. We therefore propose the designation fadM in place of ybaW. Although FadR regulation of fadM expression had the pattern typical of fad regulon genes, its modulation by the cyclic AMP (cAMP) receptor protein-cAMP complex (CRP-cAMP) global regulator was the opposite of that normally observed. CRP-cAMP generally acts as an activator of fad gene expression, consistent with the low status of fatty acids as carbon sources. However, glucose growth stimulated fadM expression relative to acetate growth, as did inactivation of CRP-cAMP, indicating that the complex acts as a negative regulator of this gene. The stimulation of fadM expression seen upon deletion of the gene encoding adenylate cyclase (Deltacya) was reversed by supplementation of the growth medium with cAMP. Nie and coworkers also reported that growth on a conjugated linoleic acid isomer yields much higher levels of FadM thioesterase activity than does growth on oleic acid. In contrast, we found that the conjugated linoleic acid isomer was only a weak inducer of fadM expression. Although the gene is not essential for growth, the high basal level of fadM expression under diverse growth conditions suggests that the encoded thioesterase has functions in addition to beta-oxidation.
authors.affiliation: Department of Microbiology, University of Illinois, B103 Chemical and Life Sciences Laboratory, 601 S. Goodwin Ave., Urbana, IL 61801, USA.
authors.forename: Youjun
authors.initials: Y
authors.lastname: Feng
authors.forename: John E
authors.initials: JE
authors.lastname: Cronan
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D008969:Molecular Sequence Data; D018085:Regulon; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D013869:Thiolester Hydrolases / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C057119:FadR protein, Bacteria; D012097:Repressor Proteins; C544474:FadM protein, E coli; D013869:Thiolester Hydrolases
references.citation: J Bacteriol. 2001 Oct;183(20):5982-90
references.pmid: 11566998
references.citation: Gene. 2002 May 15;290(1-2):153-61
references.pmid: 12062810
references.citation: Mol Microbiol. 2003 Feb;47(3):793-805
references.pmid: 12535077
references.citation: Microbiology (Reading). 2006 Aug;152(Pt 8):2207-2219
references.pmid: 16849788
references.citation: Curr Opin Microbiol. 1999 Apr;2(2):195-201
references.pmid: 10322165
references.citation: J Bacteriol. 1997 Mar;179(5):1819-23
references.pmid: 9045847
references.citation: Nucleic Acids Res. 2006;34(20):6001-14
references.pmid: 17068078
references.citation: J Bacteriol. 1981 Oct;148(1):83-90
references.pmid: 7026540
references.citation: Eur J Biochem. 1971 Apr;19(3):442-50
references.pmid: 4928881
references.citation: J Bacteriol. 2005 Oct;187(20):6893-901
references.pmid: 16199558
references.citation: J Am Chem Soc. 2007 Dec 19;129(50):15668-76
references.pmid: 18041838
references.citation: Methods. 2001 Dec;25(4):402-8
references.pmid: 11846609
references.citation: J Bacteriol. 1974 Mar;117(3):1178-83
references.pmid: 4360540
references.citation: Cell. 1992 Aug 21;70(4):671-9
references.pmid: 1505031
references.citation: Biochemistry. 2008 Sep 9;47(36):9618-26
references.pmid: 18702504
references.citation: J Bacteriol. 1981 Nov;148(2):521-6
references.pmid: 6271734
references.citation: J Bacteriol. 2006 Jan;188(2):599-608
references.pmid: 16385050
references.citation: Biochim Biophys Acta. 2001 May 5;1547(1):1-17
references.pmid: 11343786
references.citation: J Biol Chem. 2002 May 3;277(18):15558-65
references.pmid: 11859088
references.citation: J Bacteriol. 2008 Nov;190(22):7567-78
references.pmid: 18723622
references.citation: Mol Gen Genet. 1993 Sep;240(3):339-47
references.pmid: 8413182
references.citation: J Biol Chem. 1993 May 5;268(13):9238-45
references.pmid: 8098033
references.citation: Proc Natl Acad Sci U S A. 2000 Jun 6;97(12):6640-5
references.pmid: 10829079
references.citation: Microbiology (Reading). 1995 Aug;141 ( Pt 8):1901-1907
references.pmid: 7551052
references.citation: J Bacteriol. 1996 Aug;178(15):4704-9
references.pmid: 8755903
references.citation: Gene. 1995 May 26;158(1):9-14
references.pmid: 7789817
references.citation: Biochemistry. 2008 Jul 22;47(29):7744-51
references.pmid: 18576672
references.citation: Eur J Biochem. 1969 Feb;7(4):559-74
references.pmid: 4887396
references.citation: Mol Microbiol. 1998 Aug;29(4):937-43
references.pmid: 9767562
references.citation: Science. 1967 May 5;156(3775):597-604
references.pmid: 5337175
references.citation: Biochem J. 1988 Aug 1;253(3):809-18
references.pmid: 2845937
references.citation: J Bacteriol. 1985 Feb;161(2):583-8
references.pmid: 3881402
references.citation: Mol Microbiol. 1998 Jan;27(1):1-8
references.pmid: 9466250
references.citation: Curr Opin Microbiol. 2008 Apr;11(2):87-93
references.pmid: 18359269
references.citation: J Bacteriol. 1980 Aug;143(2):971-80
references.pmid: 6162838
references.citation: Mol Microbiol. 2007 Nov;66(3):622-32
references.pmid: 17877713
references.citation: J Bacteriol. 2002 Jul;184(13):3759-64
references.pmid: 12057976
references.citation: Annu Rev Microbiol. 1989;43:317-43
references.pmid: 2679357
references.citation: Proc Natl Acad Sci U S A. 1997 Nov 25;94(24):12914-9
references.pmid: 9371775
references.citation: J Mol Biol. 1991 Dec 20;222(4):843-9
references.pmid: 1722255