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Structure of a conserved dimerization domain within the F-box protein Fbxo7 and the PI31 proteasome inhibitor

Kirk, R. and Laman, H. and Knowles, P.P. and Murray-Rust, J. and Lomonosov, M. and Meziane, E.K. and McDonald, Neil Q. (2008) Structure of a conserved dimerization domain within the F-box protein Fbxo7 and the PI31 proteasome inhibitor. Journal of Biological Chemistry 283 (32), pp. 22325-22335. ISSN 0021-9258.

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Official URL: http://dx.doi.org/10.1074/jbc.M709900200

Abstract

F-box proteins are the substrate-recognition components of the Skp1-Cul1-F box protein (SCF) E3 ubiquitin ligases. Here we report a structural relationship between Fbxo7, a component of the SCFFbxo7 E3 ligase, and the proteasome inhibitor PI31. SCFFbxo7 is known to catalyze the ubiquitination of hepatoma-up-regulated protein (HURP) and the inhibitor of apoptosis (IAP) protein but also functions as an activator of cyclin D-Cdk6 complexes. We identify PI31 as an Fbxo7·Skp1 binding partner and show that this interaction requires an N-terminal domain present in both proteins that we term the FP (Fbxo7/PI31) domain. The crystal structure of the PI31 FP domain reveals a novel α/β-fold. Biophysical and mutational analyses are used to map regions of the PI31 FP domain mediating homodimerization and required for heterodimerization with Fbxo7·Skp1. Equivalent mutations in Fbxo7 ablate interaction with PI31 and also block Fbxo7 homodimerization. Knockdown of Fbxo7 does not affect PI31 levels arguing against PI31 being a substrate for SCFFbxo7. We present a model for FP domain-mediated dimerization of SCFFbxo7 and PI31.

Item Type: Article
School or Research Centre: Birkbeck Schools and Research Centres > School of Science > Biological Sciences
Depositing User: Administrator
Date Deposited: 04 Aug 2010 14:09
Last Modified: 17 Apr 2013 12:17
URI: http://eprints.bbk.ac.uk/id/eprint/1031

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