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bioRxiv · 10.1101/483024

Structural basis of Cullin-2 RING E3 ligase regulation by the COP9 signalosome

Faull, S. V.·Lau, A.·Martens, C.·Ahdash, Z.·Yebenes, H.·Schmidt, C.·Beuron, F.·Cronin, N. B.·Morris, E. P.·Politis, A.
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Abstract

Cullin-Ring E3 Ligases (CRLs) regulate a multitude of cellular pathways through specific substrate receptors. The COP9 signalosome (CSN) deactivates CRLs by removing NEDD8 (N8) from activated Cullins. The structure of stable CSN-CRL can be used to understand this mechanism of regulation. Here we present the first structures of the neddylated and deneddylated CSN-CRL2 complexes by combining single particle cryo-electron microscopy (cryo-EM) with chemical cross-linking mass spectrometry (MS). These structures reveal a conserved mechanism of CSN activation, consisting of conformational clamping of the CRL2 substrate by CSN2/CSN4, release of the catalytic CSN5/CSN6 heterodimer and finally activation of the CSN5 deneddylation machinery. Using hydrogen deuterium exchange-MS we show that CRL2 binding and conformational activation of CSN5/CSN6 occur in a neddylation-independent manner. The presence of NEDD8 is required to activate the CSN5 active site. Overall, by synergising cryo-EM with MS, we identified novel sensory regions of the CSN that mediate its stepwise activation mechanism and provide a framework for better understanding the regulatory mechanism of other Cullin family members.\n\nOne sentence summaryStructure and dynamics of the CSN-CRL2 complexes assessed by cryo-electron microscopy and structural mass spectrometry.

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Faull, S. V., Lau, A., Martens, C., Ahdash, Z., Yebenes, H., Schmidt, C., Beuron, F., Cronin, N. B., Morris, E. P., Politis, A.. 2018-11-29. Structural basis of Cullin-2 RING E3 ligase regulation by the COP9 signalosome. https://doi.org/10.1101/483024

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