title: Translational coupling of nasST expression in Azotobacter vinelandii prevents overexpression of the nasT gene.
abstract: The nasST operon encodes the transcriptional regulators of assimilatory nitrate reductase operons in phylogenetically diverse bacteria. NasT is a RNA-binding antiterminator and helps RNA polymerase read through the regulatory terminator sequences upstream of the structural genes. NasS senses nitrate and nitrite and regulates the activity of NasT through stoichiometric interaction. In this study, we analyzed the nasST sequence in Azotobacter vinelandii and revealed that the nasS and nasT genes overlap by 19 nucleotides. Our genetic analyses suggested that translational initiation of NasT was coupled with NasS translation, a regulatory mechanism that prevents overproduction of NasT. The significance of tight control of nasT expression was demonstrated in a nasT-overexpression strain, where expression of the assimilatory nitrate reductase operon was deregulated.
authors.affiliation: The School of Plant Sciences, University of Arizona, Tucson, AZ, USA; Department of Medicine, Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, VA, USA.
authors.forename: Baomin
authors.initials: B
authors.lastname: Wang
authors.forename: Christopher
authors.initials: C
authors.lastname: Rensing
authors.forename: Leland S
authors.initials: LS
authors.lastname: Pierson
authors.forename: Hui
authors.initials: H
authors.lastname: Zhao
authors.forename: Christina
authors.initials: C
authors.lastname: Kennedy
mesh_terms: D016948:Azotobacter vinelandii / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; C098638:NASS protein, Azotobacter vinelandii; C098639:NAST protein, Azotobacter vinelandii; D012097:Repressor Proteins; D015534:Trans-Activators
keywords: antitermination; nitrate reductase; nitrite reductase; overlapping genes; posttranscriptional regulation; two-component regulatory system