title: Effects of mercury on the structure and activity of BLM642-1290 recombinant helicase.
abstract: OBJECTIVE
  Bloom's syndrome is an autosomal recessive disorder characterized by genomic instability and a predisposition to many cancers. Mutations of the BLM gene (encoding a BLM helicase) may form a structure of the etiology of this disease. As a global pollutant, mercury poses a major threat to human health. The current study was conducted to elucidate the effects of Hg(2+) on the structure and activity of BLM642-1290 recombinant helicase, and to further explore the molecular mechanisms of mercury toxicity to the DNA helicase.
  
  
  METHODS
  The effects of Hg(2+) on biological activity and structure of BLM642-1290 recombinant helicase were determined by fluorescence polarized, ultraviolet spectroscopic, and free-phosphorus assay technologies, respectively.
  
  
  RESULTS
  The helicase activity, the DNA-binding activity, and the ATPase activity of BLM642-1290 recombinant helicase were inhibited by Hg(2+) treatment. The LMCT (ligand-to-metal charge transition) peaks of the helicase were enhanced with the increase of the Hg(2+) level. The LMCT peaks of the same concentration of helicase gradually increased over time.
  
  
  CONCLUSIONS
  The biological activity of BLM642-1290 recombinant helicase is inhibited by Hg(2+) treatment. The conformation of the helicase is significantly altered by Hg(2+). There exist two binding sites between Hg(2+) and the helicase, which are located in the amino acid residues 1063-1066 and 940-944 of the helicase, respectively.
authors: Guizhou Key Laboratory of Animal Genetics, Breeding and Reproduction, College of Animal Science, Guizhou University, Guiyang 550025, Guizhou, China.
authors: Xiang
authors: X
authors: Chen
authors: Heng
authors: H
authors: Luo
authors: Lixia
authors: L
authors: Duan
authors: Qinghe
authors: Q
authors: Xu
authors: Yong
authors: Y
authors: Zhang
authors: Houqiang
authors: H
authors: Xu
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D001483:Base Sequence; D017931:DNA Primers; D005454:Fluorescence Polarization; D006801:Humans; D008628:Mercury / Q000633:toxicity*; D011487:Protein Conformation; D053484:RecQ Helicases / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet; D013329:Structure-Activity Relationship
chemical_list: D017931:DNA Primers; D011994:Recombinant Proteins; D000251:Adenosine Triphosphatases; C097151:Bloom syndrome protein; D053484:RecQ Helicases; D008628:Mercury