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Related functional domains in virus DNA polymerases
Abstract:
Analysis of the lesions in several drug-resistant DNA polymerase mutants of herpes simplex virus along with comparative analysis of the published polymerase sequences of other human herpesviruses has shown that most lesions (five out of six) are substitutions at amino acid residues conserved in all four polymerases. Furthermore, the majority of lesions are in regions of the polypeptide where there are marked clusterings of conserved residues. On the basis of these data we have identified several domains within the polypeptide which we believe may have important functional roles in the action of the enzyme. The apparent restriction in the potential sites of lesions conferring drug resistance may explain the difficulty in selecting such mutants using acyclovir (ACV) in culture and their failure to emerge so far during ACV therapy. Extension of the comparative analysis to the polymerases of adenovirus type 2, vaccinia virus and phage phi 29 suggests that these enzymes also possess domains homologous to those most conserved in the herpes polymerases (regions I-III) and that these domains have a similar linear spatial distribution on the polypeptides. The results are discussed in relation to the known function of the DNA polymerases.
Insights
Drug resistance in herpes simplex virus DNA polymerase mutants primarily involves conserved amino acid substitutions. These findings identify key functional domains and explain challenges in developing acyclovir-resistant therapies.
Area of Science:
- Virology
- Molecular Biology
- Biochemistry
Background:
- Herpes simplex virus (HSV) DNA polymerase is a target for antiviral drugs like acyclovir (ACV).
- Drug resistance can arise from mutations in the viral DNA polymerase.
- Understanding these mutations is crucial for developing effective antiviral therapies.
Purpose of the Study:
- To analyze drug-resistant mutations in HSV DNA polymerase.
- To identify conserved domains within herpesvirus DNA polymerases.
- To compare these domains with those in other viral DNA polymerases.
Main Methods:
- Analysis of drug-resistant DNA polymerase mutants of herpes simplex virus.
- Comparative sequence analysis of DNA polymerases from human herpesviruses, adenovirus type 2, vaccinia virus, and phage phi 29.
Main Results:
- Most drug resistance lesions (5/6) are substitutions at amino acid residues conserved across all four human herpesviruses.
- These lesions cluster in regions of high residue conservation within the polypeptide.
- Homologous domains (regions I-III) were identified in adenovirus, vaccinia, and phage phi 29 DNA polymerases, with similar spatial distribution.
Conclusions:
- Identified conserved domains likely play critical functional roles in viral DNA polymerase activity.
- The limited sites for drug resistance mutations may explain the difficulty in selecting acyclovir-resistant mutants in vitro and in vivo.
- Conserved domains in herpesvirus DNA polymerases are also present in other viral DNA polymerases, suggesting shared functional importance.