Effect of ?,?-CHF- and ?,?-CHCl-dGTP halogen atom stereochemistry on the transition state of DNA polymerase ?.

ABSTRACT: Recently, we synthesized the first individual ?,?-CHX-dGTP diastereomers [(R)- or (S)-CHX, where X is F or Cl] and determined their structures in ternary complexes with DNA polymerase ? (pol ?). We now report stereospecificity by pol ? on the mixed ?,?-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 ? (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.

SUBMITTER: Oertell K 

PROVIDER: S-EPMC3548995 | biostudies-other | 2012 Oct

REPOSITORIES: biostudies-other