title: A truncated two-alpha-helix F-box present in poxvirus ankyrin-repeat proteins is sufficient for binding the SCF1 ubiquitin ligase complex.
abstract: Poxviruses encode a large family of ankyrin-repeat (ANK) proteins, most of which contain an F-box-like motif necessary for the interaction of the ANK proteins with SCF1 (Skp1-Cullin1-F-box) complexes. The viral motif is generally truncated compared with the three-alpha-helix cellular F-box. Cellular F-box alpha-helices 1-3 and regions C-terminal to them have been shown to contribute to Skp1 binding. We report that the poxvirus F-boxes generally contain only two alpha-helices, corresponding to cellular F-box alpha-helices 1 and 2. A third alpha-helix was detected in some poxvirus F-boxes, but was not predicted to interact with Skp1. All but one of the poxvirus ANK/F-box proteins examined terminated directly after the F-box, excluding any contribution by C-terminal regions to the binding of Skp1. Here we show that, despite this truncation, the F-box of a prototypical poxvirus ANK protein, containing two alpha-helices, is not only necessary but also sufficient for interaction with SCF1.
authors.affiliation: Virus Research Unit, Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9016, New Zealand.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Sonnberg
authors.affiliation: Virus Research Unit, Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9016, New Zealand.
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Fleming
authors.affiliation: Virus Research Unit, Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9016, New Zealand.
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Mercer
mesh_terms: D000595:Amino Acid Sequence; D017089:Ankyrin Repeat; D044783:F-Box Proteins / Q000737:chemistry* / Q000378:metabolism*; D015967:Gene Expression Regulation, Viral / Q000502:physiology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011212:Poxviridae / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D044843:SKP Cullin F-Box Protein Ligases / Q000378:metabolism*; D014764:Viral Proteins / Q000737:chemistry* / Q000378:metabolism
chemical_list: D044783:F-Box Proteins; D014764:Viral Proteins; D044843:SKP Cullin F-Box Protein Ligases