title: NpdR, a repressor involved in 2,4,6-trinitrophenol degradation in Rhodococcus opacus HL PM-1.
abstract: Rhodococcus opacus HL PM-1 utilizes 2,4,6-trinitrophenol (picric acid) as a sole nitrogen source. The initial attack on picric acid occurs through two hydrogenation reactions. Hydride transferase II (encoded by npdI) and hydride transferase I (encoded by npdC) are responsible for the hydride transfers. Database searches with the npd genes have indicated the presence of a putative transcriptional regulator, npdR. Here, the npdR gene was expressed in Escherichia coli, and the protein was purified and shown to form a complex with intergenic regions between open reading frames A and B and between npdH and npdI within the npd gene cluster. A change in DNA-NpdR complex formation occurred in the presence of 2,4-dinitrophenol, picric acid, 2-chloro-4,6-dinitrophenol, and 2-methyl-4,6-dinitrophenol. By constructing a promoter-probe vector, we demonstrated that both intergenic regions caused the expression of reporter gene xylE. Hence, both of these regions contain promoters. A deletion mutant of R. opacus HL PM-1 was constructed in which part of npdR was deleted. The expression of npdI and npdC was induced by 2,4-dinitrophenol in the wild-type strain, while in the mutant these genes were constitutively expressed. Hence, NpdR is a repressor involved in picric acid degradation.
authors.affiliation: Institute of Microbiology, University of Stuttgart, 70550 Stuttgart, Germany.
authors.forename: Dang P
authors.initials: DP
authors.lastname: Nga
authors.forename: Josef
authors.initials: J
authors.lastname: Altenbuchner
authors.forename: Gesche S
authors.initials: GS
authors.lastname: Heiss
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001673:Biodegradation, Environmental; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D019077:Helix-Turn-Helix Motifs; D006865:Hydrogenation; D008969:Molecular Sequence Data; D009876:Operon; D010851:Picrates / Q000378:metabolism*; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012240:Rhodococcus / Q000235:genetics / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D010851:Picrates; D012097:Repressor Proteins; D014157:Transcription Factors; C067479:IclR protein, E coli; C005858:picric acid