Linkage via K27 bestows ubiquitin chains with unique properties among polyubiquitins

Abstract : Polyubiquitination, a critical protein post-translational modification, signals for a diverse set of cellular events via the different isopeptide linkages formed between the C terminus of one ubiquitin (Ub) and the epsilon-amine of K6, K11, K27, K29, K33, K48, or K63 of a second Ub. We assembled di-ubiquitins (Ub(2)) comprising every lysine linkage and examined them biochemically and structurally. Of these, K27-Ub(2) is unique as it is not cleaved by most deubiquitinases. As this remains the only structurally uncharacterized lysine linkage, we comprehensively examined the structures and dynamics of K27-Ub(2) using nuclear magnetic resonance, small-angle neutron scattering, and in silico ensemble modeling. Our structural data provide insights into the functional properties of K27-Ub(2), in particular that K27-Ub(2) may be specifically recognized by K48-selective receptor UBA2 domain from proteasomal shuttle protein hHR23a. Binding studies and mutagenesis confirmed this prediction, further highlighting structural/recognition versatility of polyubiquitins and the potential power of determining function from elucidation of conformational ensembles
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Soumis le : dimanche 4 septembre 2016 - 09:35:11
Dernière modification le : jeudi 8 février 2018 - 11:10:22

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Carlos Castaneda, Emma K Dixon, Olivier Walker, Apurva Chaturvedi, Mark A Nakasone, et al.. Linkage via K27 bestows ubiquitin chains with unique properties among polyubiquitins. Structure, Elsevier (Cell Press), 2016, 24 (3), pp.423-436. 〈10.1016/j.str.2016.01.007〉. 〈hal-01359763〉



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