Budin-Verneuil Aurélie, Maguin Emmanuelle, Auffray Yanick, Ehrlich S Dusko, Pichereau Vianney
Laboratoire de Microbiologie de l'Environnement, EA956-USC INRA 2017, IRBA, Université de Caen, 14032 Caen Cedex, France.
FEMS Microbiol Lett. 2005 Sep 15;250(2):189-94. doi: 10.1016/j.femsle.2005.07.007.
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.
环丙烷脂肪酸合酶（cfa）催化将甲基从S-腺苷甲硫氨酸（SAM）转移至不饱和脂肪酸。Northern印迹实验表明，乳酸乳球菌MG1363的cfa基因主要与metK（编码SAM合成酶的基因）一起作为双顺反子转录本表达，并且受到酸度的高度诱导。通过5'-RACE PCR对cfa启动子进行了表征，并通过克隆到pAK80质粒中与β-半乳糖苷酶融合。这种转录融合在乳酸乳球菌中受到酸度（pH 5时为23倍）以及进入稳定期（8倍）的高度诱导。有趣的是，cfa启动子的表达在积累（p）ppGpp的乳酸乳球菌relA*突变体中受到抑制，而其在乳酸乳球菌和大肠杆菌中受酸度诱导似乎与（p）ppGpp无关。
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