Ectromelia virus encodes a novel family of F-box proteins that interact with the SCF complex.

Abstract

Poxviruses are notorious for encoding multiple proteins that regulate cellular signaling pathways, including the ubiquitin-proteasome system. Bioinformatics indicated that ectromelia virus, the causative agent of lethal mousepox, encoded four proteins, EVM002, EVM005, EVM154, and EVM165, containing putative F-box domains. In contrast to cellular F-box proteins, the ectromelia virus proteins contain C-terminal F-box domains in conjunction with N-terminal ankyrin repeats, a combination that has not been previously reported for cellular proteins. These observations suggested that the ectromelia virus F-box proteins interact with SCF (Skp1, cullin-1, and F-box) ubiquitin ligases. We focused our studies on EVM005, since this protein had only one ortholog in cowpox virus. Using mass spectrometry, we identified cullin-1 as a binding partner for EVM005, and this interaction was confirmed by overexpression of hemagglutinin (HA)-cullin-1. During infection, Flag-EVM005 and HA-cullin-1 colocalized to distinct cellular bodies. Significantly, EVM005 coprecipitated with endogenous Skp1, cullin-1, and Roc1 and associated with conjugated ubiquitin, suggesting that EVM005 interacted with the components of a functional ubiquitin ligase. Interaction of EVM005 with cullin-1 and Skp1 was abolished upon deletion of the F-box, indicating that the F-box played a crucial role in interaction with the SCF complex. Additionally, EVM002 and EVM154 interacted with Skp1 and conjugated ubiquitin, suggesting that ectromelia virus encodes multiple F-box-containing proteins that regulate the SCF complex. Our results indicate that ectromelia virus has evolved multiple proteins that interact with the SCF complex.

• Authors: Nick van Buuren, Brianne Couturier, Yue Xiong, Michele Barry
• Journal: Journal of virology (J Virol) Vol. 82 Issue 20 Pg. 9917-27 (Oct 2008) ISSN: 1098-5514 [Electronic] United States
• PMID: 18684824 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• F-Box Proteins
• Ubiquitins
• Viral Proteins
• SKP Cullin F-Box Protein Ligases

Topics

• Amino Acid Sequence
• Animals
• Cell Line
• Ectromelia virus (genetics, metabolism)
• Ectromelia, Infectious (virology)
• F-Box Proteins (genetics, metabolism)
• Humans
• Mice
• Molecular Sequence Data
• Protein Binding
• SKP Cullin F-Box Protein Ligases (genetics, metabolism)
• Sequence Alignment
• Ubiquitins (metabolism)
• Viral Proteins (genetics, metabolism)