title: [Mutagenesis of cysteine residues in dptC from Salmonella enteric serovar Cerro 87 and its effects on DNA phosphorothioate modification].
abstract: OBJECTIVE
  DNA phosphorothioate modification (DNA sulfur modification, a non-bridging oxygen swapped with a sulfur) exists in diverse bacteria. Salmonella enterica serovar Cerro 87 is one of the bacteria that harbor the DNA sulfur modification. The modification is carried out by the products of a four-membered gene cluster, dptBCDE. Transformation of Escherichia coli DH10B with the dptBCDE gene cluster endows the strain with DNA sulfur modification capability. Deletion of dptC abolished the modification. Here, we studied the function of dptC in DNA sulfur modification.
  
  
  METHODS
  Six cysteine residues in dptC were mutated individually within the dptBCDE gene cluster. Mutants were then tested for DNA sulfur modification.
  
  
  RESULTS
  Among the 6 cysteine mutations (C39, C146, C262, C273, C280, and C283), 5 abolished DNA modification except for C39, suggesting that C146, C262, C273, C280, and C283 are essential for DNA sulfur modification. Sequence alignment shows that these five cysteine residues are conserved among different strains.
  
  
  CONCLUSIONS
  Mutation at anyone of C146, C262, C273, C280 and C283 of dptC abolished DNA modification. Our results shed light on further study of DNA sulfur modification biochemical pathway.
authors.affiliation: State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China. anxh2006@yahoo.com.cn
authors.forename: Xianhui
authors.initials: X
authors.lastname: An
authors.forename: Xiufen
authors.initials: X
authors.lastname: Zhou
authors.forename: Zhijun
authors.initials: Z
authors.lastname: Wang
authors.forename: Zixin
authors.initials: Z
authors.lastname: Deng
authors.forename: Jingdan
authors.initials: J
authors.lastname: Liang
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D003545:Cysteine / Q000235:genetics / Q000378:metabolism; D004269:DNA, Bacterial / Q000378:metabolism*; D007506:Iron-Sulfur Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D005810:Multigene Family; D016296:Mutagenesis; D019779:Salmonella enterica / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D007506:Iron-Sulfur Proteins; D003545:Cysteine