title: Structural basis for autoinhibition and phosphorylation-dependent activation of c-Cbl.
abstract: Cbls are RING ubiquitin ligases that attenuate receptor tyrosine kinase (RTK) signal transduction. Cbl ubiquitination activity is stimulated by phosphorylation of a linker helix region (LHR) tyrosine residue. To elucidate the mechanism of activation, we determined the structures of human CBL, a CBL-substrate peptide complex and a phosphorylated-Tyr371-CBL-E2-substrate peptide complex, and we compared them with the known structure of a CBL-E2-substrate peptide complex. Structural and biochemical analyses show that CBL adopts an autoinhibited RING conformation, where the RING's E2-binding surface associates with CBL to reduce E2 affinity. Tyr371 phosphorylation activates CBL by inducing LHR conformational changes that eliminate autoinhibition, flip the RING domain and E2 into proximity of the substrate-binding site and transform the RING domain into an enhanced E2-binding module. This activation is required for RTK ubiquitination. Our results present a mechanism for regulation of c-Cbl's activity by autoinhibition and phosphorylation-induced activation.
authors.affiliation: The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Glasgow, G61 1BD, United Kingdom.
authors.forename: Hao
authors.initials: H
authors.lastname: Dou
authors.affiliation: The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Glasgow, G61 1BD, United Kingdom.
authors.forename: Lori
authors.initials: L
authors.lastname: Buetow
authors.affiliation: The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Glasgow, G61 1BD, United Kingdom.
authors.forename: Andreas
authors.initials: A
authors.lastname: Hock
authors.affiliation: The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Glasgow, G61 1BD, United Kingdom.
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Sibbet
authors.affiliation: The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Glasgow, G61 1BD, United Kingdom.
authors.forename: Karen H
authors.initials: KH
authors.lastname: Vousden
authors.affiliation: The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Glasgow, G61 1BD, United Kingdom.
authors.forename: Danny T
authors.initials: DT
authors.lastname: Huang
mesh_terms: D018360:Crystallography, X-Ray; D006801:Humans; D008958:Models, Molecular; D010766:Phosphorylation; D011485:Protein Binding; D011487:Protein Conformation; D011499:Protein Processing, Post-Translational; D050721:Proto-Oncogene Proteins c-cbl / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D050721:Proto-Oncogene Proteins c-cbl; C067419:CBL protein, human