A screen for genetic suppressor elements of hepatitis C virus identifies a supercharged protein inhibitor of viral replication

PLoS One. 2013 Dec 31;8(12):e84022. doi: 10.1371/journal.pone.0084022. eCollection 2013.

Abstract

Genetic suppressor elements (GSEs) are biomolecules derived from a gene or genome of interest that act as transdominant inhibitors of biological functions presumably by disruption of critical biological interfaces. We exploited a cell death reporter cell line for hepatitis C virus (HCV) infection, n4mBid, to develop an iterative selection/enrichment strategy for the identification of anti-HCV GSEs. Using this approach, a library of fragments of an HCV genome was screened for sequences that suppress HCV infection. A 244 amino acid gene fragment, B1, was strongly enriched after 5 rounds of selection. B1 derives from a single-base frameshift of the enhanced green fluorescent protein (eGFP) which was used as a filler during fragment cloning. B1 has a very high net positive charge of 43 at neutral pH and a high charge-to-mass (kDa) ratio of 1.5. We show that B1 expression specifically inhibits HCV replication. In addition, five highly positively charged B1 fragments produced from progressive truncation at the C-terminus all retain the ability to inhibit HCV, suggesting that a high positive charge, rather than a particular motif in B1, likely accounts for B1's anti-HCV activity. Another supercharged protein, +36GFP, was also found to strongly inhibit HCV replication when added to cells at the time of infection. This study reports a new methodology for HCV inhibitor screening and points to the anti-HCV potential of positively charged proteins/peptides.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Antiviral Agents / pharmacology*
  • Cell Death
  • Frameshift Mutation / genetics
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / pharmacology*
  • Hepacivirus / genetics
  • Hepacivirus / pathogenicity*
  • Hepatitis C / metabolism
  • Hepatitis C / prevention & control*
  • Hepatitis C / virology
  • Humans
  • Molecular Sequence Data
  • Peptide Library
  • Suppression, Genetic / physiology*
  • Virus Replication*

Substances

  • Antiviral Agents
  • Peptide Library
  • enhanced green fluorescent protein
  • Green Fluorescent Proteins