title: Regulation of DNA phosphorothioate modifications by the transcriptional regulator DptB in Salmonella.
abstract: DNA phosphorothioate (PT) modifications, with one non-bridging phosphate oxygen replaced with sulfur, are widely but sporadically distributed in prokaryotic genomes. Short consensus sequences surround the modified linkage in each strain, although each site is only partially modified. The mechanism that maintains this low-frequency modification status is still unknown. In Salmonella enterica serovar Cerro 87, PT modification is mediated by a four-gene cluster called dptBCDE. Here, we found that deletion of dptB led to a significant increase in intracellular PT modification level. In this deletion, transcription of downstream genes was elevated during rapid cell growth. Restoration of dptB on a plasmid restored wild-type levels of expression of downstream genes and PT modification. In vitro, DptB directly protected two separate sequences within the dpt promoter region from DNase I cleavage. Each protected sequence contained a direct repeat (DR). Mutagenesis assays of the DRs demonstrated that each DR was essential for DptB binding. The observation of two shifted species by gel-shift analysis suggests dimer conformation of DptB protein. These DRs are conserved among the promoter regions of dptB homologs, suggesting that this regulatory mechanism is widespread. These findings demonstrate that PT modification is regulated at least in part at the transcriptional level.
authors.affiliation: State Key Laboratory of Microbial Metabolism, and School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200030, China.
authors.forename: Qiuxiang
authors.initials: Q
authors.lastname: Cheng
authors.affiliation: State Key Laboratory of Microbial Metabolism, and School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200030, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Cao
authors.affiliation: State Key Laboratory of Microbial Metabolism, and School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200030, China.
authors.forename: Fen
authors.initials: F
authors.lastname: Yao
authors.affiliation: State Key Laboratory of Microbial Metabolism, and School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200030, China.
authors.forename: Jinli
authors.initials: J
authors.lastname: Li
authors.affiliation: State Key Laboratory of Microbial Metabolism, and School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200030, China.
authors.forename: Zixin
authors.initials: Z
authors.lastname: Deng
authors.affiliation: State Key Laboratory of Microbial Metabolism, and School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200030, China.|Joint International Research Laboratory of Metabolic and Developmental Sciences, Shanghai Jiao Tong University, Shanghai, 200240, China.
authors.forename: Delin
authors.initials: D
authors.lastname: You
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D004269:DNA, Bacterial / Q000378:metabolism*; D005810:Multigene Family; D009154:Mutation; D054735:Phosphorothioate Oligonucleotides / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D019779:Salmonella enterica / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D054735:Phosphorothioate Oligonucleotides; D014157:Transcription Factors