Inhibition of herpes simplex virus type 1 DNA polymerase by [1R(1 alpha,2 beta,3 alpha)]-9-[2,3-bis(hydroxymethyl)cyclobutyl] guanine.
(+/-)-(1 alpha,2 beta,3 alpha)-9-[2,3-Bis(hydroxymethyl)cyclobutyl] guanine [(+/-)-BHCG] is a nucleoside analog with potent in vitro activity against herpesviruses [Tetrahedron Lett. 30:6453-6456 (1989)]. The two enantiomers have been synthesized, and their biochemical characterization is reported here. [1S(1 alpha,2 beta,3 alpha)]-9-[2,3-Bis(hydroxymethyl)cyclobutyl]guanine [(S)-BHCG] was phosphorylated by herpes simplex virus type 1 (HSV-1) thymidine kinase (Vmax = 8 nmol/hr/micrograms of enzyme), whereas [1R(1 alpha,2 beta,3 alpha)]-9-[2,3-bis(hydroxymethyl)cyclobutyl]guanine [(R)-BHCG] was a poor substrate for the viral thymidine kinase under these conditions. The triphosphate of each enantiomer was enzymatically synthesized, and both enantiomers competitively inhibited HSV-1 DNA polymerase with respect to dGTP. However, the potency of (R)-BHCG-TP was 4 orders of magnitude greater than that of (S)-BHCG-TP. (R)-BHCG-TP inhibited HeLa DNA polymerase alpha, but the inhibition constant was 30-fold higher than that for the viral DNA polymerase. In comparison, (S)-BHCG-TP was a very poor inhibitor of DNA polymerase alpha. (R)-[3H]BHCG-TP could be incorporated into a synthetic DNA template by HSV-1 DNA polymerase at 80% the extent of dGTP under the assay conditions used and, therefore, could act as an alternative substrate. Incorporation of (R)-BHCG-TP was similar to that observed for acyclovir triphosphate and ganciclovir triphosphate, based on maximal velocities. In contrast, HSV-1 DNA polymerase did not incorporate (S)-BHCG-TP into DNA. Compared with dGTP, only limited extension (10%) of the DNA primer by HSV-1 DNA polymerase occurred after incorporation of (R)-BHCG-TP and, therefore, (R)-BHCG-TP acts as a nonobligate chain terminator.
Terry
B J
BJ
Department of Virology, Bristol-Myers Squibb Pharmaceutical Research Institute, Princeton, New Jersey 08543-4000.
Cianci
C W
CW
Hagen
M E
ME
D000998:Antiviral Agents / Q000494:pharmacology*; D001483:Base Sequence; D004256:DNA Polymerase I / Q000037:antagonists & inhibitors*; D004279:DNA, Viral / Q000378:metabolism; D003845:Deoxycytosine Nucleotides / Q000378:metabolism; D003848:Deoxyguanine Nucleotides / Q000378:metabolism; D006147:Guanine / Q000031:analogs & derivatives* / Q000494:pharmacology; D008969:Molecular Sequence Data; D010766:Phosphorylation; D018139:Simplexvirus / Q000201:enzymology* / Q000378:metabolism; D013237:Stereoisomerism; D014764:Viral Proteins / Q000037:antagonists & inhibitors*
D000998:Antiviral Agents; D004279:DNA, Viral; D003845:Deoxycytosine Nucleotides; D003848:Deoxyguanine Nucleotides; D014764:Viral Proteins; C024107:2'-deoxycytidine 5'-triphosphate; D006147:Guanine; C029603:deoxyguanosine triphosphate; C063638:lobucavir; D004256:DNA Polymerase I