title: Effect of β,γ-CHF- and β,γ-CHCl-dGTP halogen atom stereochemistry on the transition state of DNA polymerase β.
abstract: Recently, we synthesized the first individual β,γ-CHX-dGTP diastereomers [(R)- or (S)-CHX, where X is F or Cl] and determined their structures in ternary complexes with DNA polymerase β (pol β). We now report stereospecificity by pol β on the mixed β,γ-CHX diastereomer pairs using nuclear magnetic resonance and on the separate diastereomers using transient kinetics. For both the F and Cl diastereomers, the R isomer is favored over the S isomer for G·C correct incorporation, with stereospecificities [(k(pol)/K(d))(R)/(k(pol)/K(d))(S)] of 3.8 and 6.3, respectively, and also for G·T misincorporation, with stereospecificities of 11 and 7.8, respectively. Stereopreference for the (R)-CHF-dGTP diastereomer was abolished for k(pol) but not K(d) with mutant pol β (R183A). These compounds constitute a new class of stereochemical probes for active site interactions involving halogen atoms. As Arg183 is unique in family X pols, the design of CXY deoxyribonucleotide analogues to enhance interaction is a possible strategy for inhibiting BER selectively in cancer cells.
authors.affiliation: Department of Chemistry, University of Southern California, Los Angeles, CA 90089, USA.
authors.forename: Keriann
authors.initials: K
authors.lastname: Oertell
authors.forename: Yue
authors.initials: Y
authors.lastname: Wu
authors.forename: Valeria M
authors.initials: VM
authors.lastname: Zakharova
authors.forename: Boris A
authors.initials: BA
authors.lastname: Kashemirov
authors.forename: David D
authors.initials: DD
authors.lastname: Shock
authors.forename: William A
authors.initials: WA
authors.lastname: Beard
authors.forename: Samuel H
authors.initials: SH
authors.lastname: Wilson
authors.forename: Charles E
authors.initials: CE
authors.lastname: McKenna
authors.forename: Myron F
authors.initials: MF
authors.lastname: Goodman
mesh_terms: D020134:Catalytic Domain / Q000187:drug effects; D004247:DNA / Q000378:metabolism; D019951:DNA Polymerase beta / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003848:Deoxyguanine Nucleotides / Q000737:chemistry* / Q000494:pharmacology*; D006219:Halogens / Q000737:chemistry* / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D019906:Nuclear Magnetic Resonance, Biomolecular; D017354:Point Mutation; D013237:Stereoisomerism; D013379:Substrate Specificity
chemical_list: D003848:Deoxyguanine Nucleotides; D006219:Halogens; C029603:deoxyguanosine triphosphate; D004247:DNA; D019951:DNA Polymerase beta