Modification of papillomavirus E2 proteins by the small ubiquitin-like modifier family members (SUMOs).
Papillomavirus E2 proteins are critical regulatory proteins that function in replication, genome segregation, and viral transcription, including control of expression of the viral oncogenes, E6 and E7. Sumoylation is a post-translational modification that has been shown to target and modulate the function of many transcription factors, and we now demonstrate that E2 proteins are sumoylated. Both bovine and human papillomavirus E2 proteins bind to the SUMO conjugation enzyme, Ubc9, and using in vitro and E. coli sumoylation systems, these E2 proteins were readily modified by SUMO proteins. In vivo experiments further confirmed that E2 can be sumoylated by SUMO1, SUMO2, or SUMO3. Mapping studies identified lysine 292 as the principal residue for covalent conjugation of SUMO to HPV16 E2, and a lysine 292 to arginine mutant showed defects for both transcriptional activation and repression. The expression levels, intracellular localization, and the DNA-binding activity of HPV16 E2 were unchanged by this K292R mutation, suggesting that the transcriptional defect reflects a functional contribution by sumoylation at this residue. This study provides evidence that sumoylation has a role in the regulation of papillomavirus E2, and identifies a new mechanism for the modulation of E2 function at the post-translational level.
Wu
Yu-Chieh
YC
Department of Microbial and Molecular Pathogenesis, College of Medicine, Texas A & M Health Science Center, College Station, TX 77843-1114, USA.
Roark
Ashley A
AA
Bian
Xue-Lin
XL
Wilson
Van G
VG
D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D002417:Cattle; D002460:Cell Line; D004279:DNA, Viral / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D006801:Humans; D016297:Mutagenesis, Site-Directed; D020125:Mutation, Missense; D009856:Oncogene Proteins, Viral / Q000235:genetics / Q000378:metabolism*; D027383:Papillomaviridae / Q000502:physiology; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D025842:SUMO-1 Protein / Q000378:metabolism*; D025841:Small Ubiquitin-Related Modifier Proteins / Q000378:metabolism*; D014158:Transcription, Genetic; D044763:Ubiquitin-Conjugating Enzymes / Q000378:metabolism; D014452:Ubiquitins / Q000378:metabolism*; D014764:Viral Proteins / Q000378:metabolism*; D000098843:Ubiquitin-Conjugating Enzyme UBC9
D004279:DNA, Viral; D004268:DNA-Binding Proteins; C051550:E2 protein, Bovine papillomavirus; D009856:Oncogene Proteins, Viral; D025842:SUMO-1 Protein; C117909:SUMO2 protein, human; C492189:SUMO3 protein, human; D025841:Small Ubiquitin-Related Modifier Proteins; D014452:Ubiquitins; D014764:Viral Proteins; C076036:oncogene protein E2, Human papillomavirus type 1; D044763:Ubiquitin-Conjugating Enzymes; D000098843:Ubiquitin-Conjugating Enzyme UBC9