title: QscR acts as an intermediate in gacA-dependent regulation of PCA biosynthesis in Pseudomonas sp. M-18.
abstract: The qscR gene, encoding a quorum sensing regulator, was cloned and the qscR-null mutant strain M-18Q derived from Pseudomonas sp. M-18 was constructed to study the effect of the qscR gene on biosynthesis of phenazine-1-carboxylic acid (PCA) and pyoluteorin (Plt) in strain M-18. Results showed that the PCA produced in the mutant increased four- to six-fold, while the synthesis of Plt was barely influenced in comparison with the wild type. The results were confirmed by complementation with the qscR gene in trans in strain M-18Q. The negative effect of the qscR gene on PCA production was further confirmed by analysis of beta-galactosidase activities from the translational phzA'-lacZ' fusion. Furthermore, by introducing a qscR-lacZ transcriptional fusion vector to strains M-18, M-18Q, and M-18G, a gacA inactivation mutant in strain M-18, respectively, it was found that beta-galactosidase activity in both strain M-18G and strain M-18Q was decreased to half that in the wild type. This suggested that QscR might be involved in autoinducing its own gene expression and act as an intermediate in GacA-dependent gene regulation as well. The result was further demonstrated by the overexpression of the gacA gene in strain M-18Q.
authors.affiliation: Ministry of Education, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, People's Republic of China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
authors.forename: Xianqing
authors.initials: X
authors.lastname: Huang
authors.forename: Hongbo
authors.initials: H
authors.lastname: Hu
authors.forename: Xuehong
authors.initials: X
authors.lastname: Zhang
authors.forename: Yuquan
authors.initials: Y
authors.lastname: Xu
mesh_terms: D019677:Artificial Gene Fusion; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D005816:Genetic Complementation Test; D016254:Mutagenesis, Insertional; D010619:Phenazines / Q000378:metabolism; D010636:Phenols / Q000378:metabolism*; D011549:Pseudomonas / Q000502:physiology*; D011758:Pyrroles / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; C091100:GacA protein, Bacteria; D010619:Phenazines; D010636:Phenols; D011758:Pyrroles; C434259:QscR protein, Pseudomonas aeruginosa; D012097:Repressor Proteins; C095503:pyoluteorin; C037165:1-phenazinecarboxylic acid; D001616:beta-Galactosidase