title: Characterization of magnesium requirement of human 5'-tyrosyl DNA phosphodiesterase mediated reaction.
abstract: BACKGROUND
  Topo-poisons can produce an enzyme-DNA complex linked by a 3'- or 5'-phosphotyrosyl covalent bond. 3'-phosphotyrosyl bonds can be repaired by tyrosyl DNA phosphodiesterase-1 (TDP1), an enzyme known for years, but a complementary human enzyme 5'-tyrosyl DNA phosphodiesterase (hTDP2) that cleaves 5'-phosphotyrosyl bonds has been reported only recently. Although hTDP2 possesses both 3'- and 5'- tyrosyl DNA phosphodiesterase activity, the role of Mg2+ in its activity was not studied in sufficient details.
  
  
  RESULTS
  In this study we showed that purified hTDP2 does not exhibit any 5'-phosphotyrosyl phosphodiesterase activity in the absence of Mg2+/Mn2+, and that neither Zn2+ or nor Ca2+ can activate hTDP2. Mg2+ also controls 3'-phosphotyrosyl activity of TDP2. In MCF-7 cell extracts and de-yolked zebrafish embryo extracts, Mg2+ controlled 5'-phosphotyrosyl activity. This study also showed that there is an optimal Mg2+ concentration above which it is inhibitory for hTDP2 activity.
  
  
  CONCLUSIONS
  These results altogether reveal the optimal Mg2+ requirement in hTDP2 mediated reaction.
authors.affiliation: Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA. sa354@georgetown.edu
authors.forename: Sanjay
authors.initials: S
authors.lastname: Adhikari
authors.forename: Soumendra K
authors.initials: SK
authors.lastname: Karmahapatra
authors.forename: Tejaswita M
authors.initials: TM
authors.lastname: Karve
authors.forename: Sanjona
authors.initials: S
authors.lastname: Bandyopadhyay
authors.forename: Jordan
authors.initials: J
authors.lastname: Woodrick
authors.forename: Praveen V
authors.initials: PV
authors.lastname: Manthena
authors.forename: Eric
authors.initials: E
authors.lastname: Glasgow
authors.forename: Stephen
authors.initials: S
authors.lastname: Byers
authors.forename: Tapas
authors.initials: T
authors.lastname: Saha
authors.forename: Aykut
authors.initials: A
authors.lastname: Uren
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002457:Cell Extracts / Q000737:chemistry; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins; D004591:Electrophoresis, Polyacrylamide Gel; D004625:Embryo, Nonmammalian / Q000196:embryology / Q000201:enzymology*; D004789:Enzyme Activation; D004926:Escherichia coli / Q000235:genetics; D029941:Fish Proteins / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D061986:MCF-7 Cells; D008274:Magnesium / Q000378:metabolism*; D008345:Manganese / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D009841:Oligonucleotides / Q000378:metabolism; D010727:Phosphoric Diester Hydrolases; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D014020:Tissue Extracts / Q000737:chemistry; D014157:Transcription Factors / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D015027:Zebrafish / Q000196:embryology / Q000378:metabolism*; D015032:Zinc / Q000378:metabolism
chemical_list: D002457:Cell Extracts; D004268:DNA-Binding Proteins; D029941:Fish Proteins; D009687:Nuclear Proteins; D009841:Oligonucleotides; D011994:Recombinant Proteins; D014020:Tissue Extracts; D014157:Transcription Factors; D008345:Manganese; D004247:DNA; D010727:Phosphoric Diester Hydrolases; C474866:TDP2 protein, human; D008274:Magnesium; D015032:Zinc; D002118:Calcium