title: Regulation of the cyclopropane synthase cfaB gene in Pseudomonas putida KT2440.
abstract: In Pseudomonas putida, as in many other eubacteria, cyclopropane fatty acids (CFAs) accumulate in the membrane during the stationary phase of growth. Here, we show that cfaB gene expression in P. putida KT2440 is dependent on the RpoS sigma factor that recognizes the sequence 5'-CTACTCT-3' between -8 and -14. We have carried out a mutational study of the cfa promoter and have determined that positions -9, -12, -13 and -14 are the most critical for maximal activity. In P. putida, the substrates of the CFA synthase, cis-unsaturated fatty acids (cis-UFAs), are also substrates for another stress-related enzyme, the cis-trans isomerase (CTI). Despite using the same substrates, we have found that the activity of the CTI is not limited by the CFA synthase activity and vice versa. For instance, in a cfaB knockout mutant, the amount of trans-UFAs synthesized after a specific stress was no higher than in the parental background despite the fact that there are more cis-UFAs available to be used by the CTI as substrates. In this regard, in a cti-deficient mutant background, the levels of CFAs were similar to those in the parental one under the same conditions.
authors.affiliation: Consejo Superior de Investigaciones Cient´ıficas, Environmental Protection Department, Estacio´ n Experimental del Zaid´ın, Granada, Spain.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Pini
authors.forename: Patricia
authors.initials: P
authors.lastname: Godoy
authors.forename: Patricia
authors.initials: P
authors.lastname: Bernal
authors.forename: Juan-Luis
authors.initials: JL
authors.lastname: Ramos
authors.forename: Ana
authors.initials: A
authors.lastname: Segura
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D008780:Methyltransferases / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011401:Promoter Regions, Genetic; D016958:Pseudomonas putida / Q000201:enzymology* / Q000235:genetics*; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism; D019745:cis-trans-Isomerases / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D005231:Fatty Acids, Unsaturated; D012808:Sigma Factor; C069567:sigma factor KatF protein, Bacteria; D008780:Methyltransferases; C019964:cyclopropane synthetase; D019745:cis-trans-Isomerases