Abstract
An aphidicolin-resistant (Aphr) mutant of herpes simplex virus (HSV) type 2 strain 186 previously has been shown to induce an altered viral DNA polymerase that is more resistant to aphidicolin and more sensitive to phosphonoacetic acid (PAA) than is wild-type DNA polymerase. In this study the mutation responsible for the aphidicolin-resistant phenotype was physically mapped by marker transfer experiments. The physical map limits for the Aphr mutation were contained in a 1.1-kilobase pair region within the HSV DNA polymerase locus. The 1.1-kilobase-pair fragment of the Aphr mutant also conferred hypersensitivity to PAA, and DNA sequence analysis revealed an AT to GC transition within this fragment of the Aphr mutant. Analysis of the three potential open reading frames within the 1,147-base-pair fragment and comparison with the amino acid sequence of DNA polymerase of HSV type 1 indicated that the Aphr mutant polymerase had an amino acid substitution from a tyrosine to a histidine in the well-conserved region of the DNA polymerase. These results indicate that this single amino acid change can confer altered sensitivity to aphidicolin and PAA and suggest that this region may form a domain that contains the binding sites for substrates, PPi, and aphidicolin.