Cdc34p ubiquitin-conjugating enzyme is a component of the tombusvirus replicase complex and ubiquitinates p33 replication protein

J Virol. 2008 Jul;82(14):6911-26. doi: 10.1128/JVI.00702-08. Epub 2008 May 7.


To identify host proteins interacting with Tomato bushy stunt virus (TBSV) replication proteins in a genome-wide scale, we have used a yeast (Saccharomyces cerevisiae) proteome microarray carrying 4,088 purified proteins. This approach led to the identification of 58 yeast proteins that interacted with p33 replication protein. The identified host proteins included protein chaperones, ubiquitin-associated proteins, translation factors, RNA-modifying enzymes, and other proteins with yet-unknown functions. We confirmed that 19 of the identified host proteins bound to p33 in vitro or in a split-ubiquitin-based two-hybrid assay. Further analysis of Cdc34p E2 ubiquitin-conjugating enzyme, which is one of the host proteins interacting with p33, revealed that Cdc34p is a novel component of the purified viral replicase. Downregulation of Cdc34p expression in yeast, which supports replication of a TBSV replicon RNA (repRNA), reduced repRNA accumulation and the activity of the tombusvirus replicase by up to fivefold. Overexpression of wild-type Cdc34p, but not that of an E2-defective mutant of Cdc34p, increased repRNA accumulation, suggesting a significant role for the ubiquitin-conjugating enzyme function of Cdc34p in TBSV replication. Also, Cdc34p was able to ubiquitinate p33 in vitro. In addition, we have shown that p33 becomes ubiquitinated in vivo. We propose that ubiquitination of p33 likely alters its function or affects the recruitment of host factors during TBSV replication.

Publication types

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

MeSH terms

  • Anaphase-Promoting Complex-Cyclosome
  • Protein Array Analysis
  • Protein Binding
  • RNA, Viral / metabolism
  • RNA-Dependent RNA Polymerase / chemistry
  • RNA-Dependent RNA Polymerase / isolation & purification
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / metabolism
  • Tombusvirus / physiology*
  • Two-Hybrid System Techniques
  • Ubiquitin-Protein Ligase Complexes / metabolism*
  • Ubiquitination
  • Viral Proteins / metabolism*
  • Virus Replication / physiology*


  • RNA, Viral
  • Saccharomyces cerevisiae Proteins
  • Viral Proteins
  • Ubiquitin-Protein Ligase Complexes
  • Anaphase-Promoting Complex-Cyclosome
  • RNA-Dependent RNA Polymerase