Molecular and genetic evidence for a virus-encoded glycosyltransferase involved in protein glycosylation

Michael V. Graves, Cory T. Bernadt, Ronald Cerny, James L. Van Etten

Research output: Contribution to journalArticle

43 Scopus citations

Abstract

The major capsid protein, Vp54, of chlorella virus PBCV-1 is a glycoprotein that contains either one glycan of ∼30 sugar residues or two similar glycans of ∼15 residues. Previous analysis of PBCV-1 antigenic mutants that contained altered Vp54 glycans led to the conclusion that unlike other glycoprotein-containing viruses, most, if not all, of the enzymes involved in the synthesis of the Vp54 glycan are probably encoded by PBCV-1 (I.-N. Wang et al., 1993, Proc. Natl. Acad. Sci. USA 90, 3840-3844). In this report we used molecular and genetic approaches to begin to identify these virus genes. Comparing the deduced amino acid sequences of the putative 375 PBCV-1 protein-encoding genes to databases identified seven potential glycosyltransferases. One gene, designated a64r, encodes a 638-amino-acid protein that has four motifs conserved in "Fringe type" glycosyltransferases. Analysis of 13 PBCV-1 antigenic mutants revealed mutations in a64r that correlated with a specific antigenic variation. Dual-infection experiments with different antigenic mutants indicated that viruses that contained wild-type a64r could complement and recombine with viruses that contained mutant a64r to form wild-type virus. Therefore, we conclude that a64r encodes a glycosyltransferase involved in synthesizing the Vp54 glycan. This is the first report of a virus-encoded glycosyltransferase involved in protein glycosylation.

Original languageEnglish (US)
Pages (from-to)332-345
Number of pages14
JournalVirology
Volume285
Issue number2
DOIs
StatePublished - Jul 5 2001

Keywords

  • Chlorella virus
  • Glycosyltransferase
  • PBCV-1
  • Phycodnaviridae
  • Virus glycoprotein

ASJC Scopus subject areas

  • Virology

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