Inhibiting a dynamic viral protease by targeting a non-catalytic cysteine

Cell Chem Biol. 2022 May 19;29(5):785-798.e19. doi: 10.1016/j.chembiol.2022.03.007. Epub 2022 Mar 31.

Abstract

Viruses are responsible for some of the most deadly human diseases, yet available vaccines and antivirals address only a fraction of the potential viral human pathogens. Here, we provide a methodology for managing human herpesvirus (HHV) infection by covalently inactivating the HHV maturational protease via a conserved, non-catalytic cysteine (C161). Using human cytomegalovirus protease (HCMV Pr) as a model, we screened a library of disulfides to identify molecules that tether to C161 and inhibit proteolysis, then elaborated hits into irreversible HCMV Pr inhibitors that exhibit broad-spectrum inhibition of other HHV Pr homologs. We further developed an optimized tool compound targeted toward HCMV Pr and used an integrative structural biology and biochemical approach to demonstrate inhibitor stabilization of HCMV Pr homodimerization, exploiting a conformational equilibrium to block proteolysis. Irreversible HCMV Pr inhibition disrupts HCMV infectivity in cells, providing proof of principle for targeting proteolysis via a non-catalytic cysteine to manage viral infection.

Keywords: allostery; antiviral; conformational dynamics; covalent inhibitor; cytomegalovirus; dimerization; herpesvirus; irreversible electrophile; non-catalytic cysteine; protease.

MeSH terms

  • Cysteine
  • Cytomegalovirus Infections*
  • Cytomegalovirus* / physiology
  • Humans
  • Peptide Hydrolases
  • Viral Proteases

Substances

  • Peptide Hydrolases
  • Viral Proteases
  • Cysteine