title: Transcriptional regulation by TrsN of conjugative transfer genes on staphylococcal plasmid pGO1.
abstract: The major conjugative transfer gene cluster of staphylococcal plasmid pGO1 (trs) consists of 13 open reading frames (trsA to trsM) transcribed from one DNA strand and a single 189-bp open reading frame (trsN) within the first 348 bp of trs that is transcribed divergently. Promoter regions for trsN and trsA partially overlap. TrsN, a 7,181-Da protein, was purified as a fusion to glutathione S-transferase and found to have DNA-binding activity. Increasing concentrations of the fusion protein progressively retarded the gel migration of PCR-generated DNA fragments containing predicted promoters 5' to trsL, trsA, and trsN. The target sequences contained areas of identity, including regions of dyad symmetry, that were protected in DNase I footprinting studies. The binding of TrsN to its trsL target was required for this target DNA to be stably introduced into Staphylococcus aureus on a high-copy-number vector. Provision of excess TrsN from this high-copy-number vector in S. aureus decreased beta-galactosidase activity from a trsL-lacZ transcriptional fusion and decreased pGO1 conjugation frequency. Conversely, both transcription and conjugation increased in the presence of excess trsL target. We propose that TrsN negatively regulates the transcription of genes essential for conjugative transfer by binding to regions 5' to their translational start sites.
authors.affiliation: Department of Medicine, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298-0049.
authors.forename: V K
authors.initials: VK
authors.lastname: Sharma
authors.forename: J L
authors.initials: JL
authors.lastname: Johnston
authors.forename: T M
authors.initials: TM
authors.lastname: Morton
authors.forename: G L
authors.initials: GL
authors.lastname: Archer
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D001483:Base Sequence; D003001:Cloning, Molecular; D003227:Conjugation, Genetic / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial / Q000235:genetics; D005982:Glutathione Transferase / Q000096:biosynthesis / Q000235:genetics; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics; D016254:Mutagenesis, Insertional; D010957:Plasmids / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D017422:Sequence Analysis, DNA; D013211:Staphylococcus aureus / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D014170:Transformation, Genetic
chemical_list: C087724:ArtA protein, Staphylococcus aureus; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D005982:Glutathione Transferase