Transcriptional analysis of the cyclopropane fatty acid synthase gene of Lactococcus lactis MG1363 at low pH.
Cyclopropane fatty acid synthase (cfa) catalyses the transfer of a methyl group from S-adenosylmethionine (SAM) to unsaturated fatty acids. Northern blot experiments demonstrated that the Lactococcus lactis MG1363 cfa gene is mainly expressed as a bicistronic transcript together with metK, the gene encoding SAM synthetase, and is highly induced by acidity. The cfa promoter was characterized by 5'-RACE PCR, and fused to beta-galactosidase by cloning into the pAK80 plasmid. This transcriptional fusion was highly induced by acidity (23-fold at pH 5) as well as during entry into the stationary phase (8-fold) in L. lactis. Interestingly, the cfa promoter expression is repressed in a L. lactis relA* mutant which accumulates (p)ppGpp, whereas its induction by acidity appeared independent of (p)ppGpp in L. lactis and in Escherichia coli.
Budin-Verneuil
Aurélie
A
Laboratoire de Microbiologie de l'Environnement, EA956-USC INRA 2017, IRBA, Université de Caen, 14032 Caen Cedex, France.
Maguin
Emmanuelle
E
Auffray
Yanick
Y
Ehrlich
S Dusko
SD
Pichereau
Vianney
V
D000222:Adaptation, Physiological; D001483:Base Sequence; D004269:DNA, Bacterial; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D017930:Genes, Reporter; D006863:Hydrogen-Ion Concentration; D013294:Lactococcus lactis / Q000201:enzymology / Q000235:genetics*; D008025:Ligases / Q000235:genetics; D008716:Methionine Adenosyltransferase / Q000235:genetics; D008780:Methyltransferases / Q000235:genetics*; D008969:Molecular Sequence Data; D009876:Operon; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins; D014158:Transcription, Genetic; D015854:Up-Regulation; D001616:beta-Galactosidase / Q000235:genetics
D004269:DNA, Bacterial; D011993:Recombinant Fusion Proteins; D008780:Methyltransferases; C019964:cyclopropane synthetase; D008716:Methionine Adenosyltransferase; D001616:beta-Galactosidase; D008025:Ligases; C028812:guanosine 3',5'-polyphosphate synthetases