title: Transcriptional regulation of the Rhodococcus rhodochrous J1 nitA gene encoding a nitrilase.
abstract: The 1.4-kb downstream region from a nitrilase gene (nitA) of an actinomycete Rhodococcus rhodochrous J1, which is industrially in use, was found to be required for the isovaleronitrile-dependent induction of nitrilase synthesis in experiments using a Rhodococcus-Escherichia coli shuttle vector pK4 in a Rhodococcus strain. Sequence analysis of the 1.4-kb region revealed the existence of an open reading frame (nitR) of 957 bp, which would encode a protein with a molecular mass of 35,100. Deletion of the central and 3'-terminal portion of nitR resulted in the complete loss of nitrilase activity, demonstrating that nitR codes for a transcriptional positive regulator in nitA expression. The deduced amino acid sequence of nitR showed similarity to a positive regulator family including XylS from Pseudomonas putida and AraC from E. coli. By Northern blot analysis, the 1.4-kb transcripts for nitA were detected in R. rhodochrous J1 cells cultured in the presence of isovaleronitrile, but not those cultured in the absence of isovaleronitrile. The transcriptional start site for nitA was mapped to a C residue located 26 bp upstream of its translational start site. Deletion analysis to define the nitA promoter region suggested the possible participation of an inverted repeat sequence, centered on base pair -52, in induction of nitA transcription.
authors.affiliation: Department of Agricultural Chemistry, Faculty of Agriculture, Kyoto University, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Komeda
authors.forename: Y
authors.initials: Y
authors.lastname: Hori
authors.forename: M
authors.initials: M
authors.lastname: Kobayashi
authors.forename: S
authors.initials: S
authors.lastname: Shimizu
mesh_terms: D000595:Amino Acid Sequence; D000619:Aminohydrolases / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D003001:Cloning, Molecular; D018274:Electroporation; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid; D012240:Rhodococcus / Q000235:genetics*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics*; D014158:Transcription, Genetic; D014170:Transformation, Genetic
chemical_list: D001426:Bacterial Proteins; C101823:NitR protein, Rhodococcus rhodochrous; D012333:RNA, Messenger; D015534:Trans-Activators; D000619:Aminohydrolases; C021867:nitrilase