Identification of Amino Acids Essential for Viral Replication in the HCMV Helicase-Primase Complex.

Gaetan Ligat,Sandra Da Re,Sophie Alain,Sébastien Hantz

doi:10.3389/fmicb.2018.02483

Gaetan Ligat, Sandra Da Re + Show 2 more

Open Access

https://doi.org/10.3389/fmicb.2018.02483

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Abstract

Promising new inhibitors that target the viral helicase-primase complex have been reported to block replication of herpes simplex and varicella-zoster viruses, but they have no activity against human cytomegalovirus (HCMV), another herpesvirus. The HCMV helicase-primase complex (pUL105-pUL102-pUL70) is essential for viral DNA replication and could thus be a relevant antiviral target. The roles of the individual subunits composing this complex remain to be defined. By using sequence alignment of herpesviruses homologs, we identified conserved amino acids in the putative pUL105 ATP binding site and in the putative pUL70 zinc finger pattern. Mutational analysis of several of these amino acids both in pUL105 and pUL70, proved that they are crucial for viral replication. We also constructed, by homology modeling, a theoretical structure of the pUL105 N-terminal domain which indicates that the mutated conserved amino acids in this domain could be involved in ATP hydrolysis.

Highlights

Human cytomegalovirus (HCMV), a beta herpesvirus, infects 50–90% of the population worldwide
Within the putative metal-binding pattern of pUL70, we identified three cysteines (C881, C915, and C920) and one histidine (H886) that are highly conserved among herpesviruses (Figure 5A) and that could be directly involved in zinc ion binding (Figure 5B)
The helicase-primase of HCMV is essential for viral replication and represents a potential target for the development of new anti CMV compounds

Summary

Introduction

Human cytomegalovirus (HCMV), a beta herpesvirus, infects 50–90% of the population worldwide. Two helicase-primase inhibitors have been developed against alpha-herpesviruses: pritelivir (previously named BAY 57-1293 or AIC316), a Essential Residues of HCMV Helicase-Primase thiazolylamide active against herpes simplex virus types 1 and 2 (HSV-1 and -2) (Wald et al, 2014), and amenamevir (or ASP2151), an oxadiazolylphenyl derivative, active against both HSV and varicella-zoster virus (VZV or HHV-3) (Chono et al, 2010). They have been proved as efficient as acyclovir: IC50 of 0.02 μM against HSV1-2 for pritelivir and 0.03 μM for amenamevir with a CC50 > 30 μM for both drugs. Their precise site of action has not been elucidated to date and these drugs are not active against the beta-herpesviruses like HCMV (Dropulic and Cohen, 2010)

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