The cotranslational contacts between ribosome-bound nascent polypeptides and the subunits of the hetero-oligomeric chaperonin TRiC probed by photocross-linking

Etchells, S.A. and Meyer, A.S. and Yam, A.Y. and Roobol, A. and Miao, Y.W. and Shao, Y.L. and Carden, M.J. and Skach, W.R. and Frydman, J. and Johnson, A.E. (2005) The cotranslational contacts between ribosome-bound nascent polypeptides and the subunits of the hetero-oligomeric chaperonin TRiC probed by photocross-linking. Journal of Biological Chemistry, 280 (30). pp. 28118-28126. ISSN 0021-9258 . (Access to this publication is restricted)

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Abstract

The hetero-oligomeric eukaryotic chaperonin TRiC (TCP-1-ring complex, also called CCT) interacts cotranslationally with a diverse subset of newly synthesized proteins, including actin, tubulin, and luciferase, and facilitates their correct folding. A photocross-linking approach has been used to map the contacts between individual chaperonin subunits and ribosome-bound nascent chains of increasing length. Whereas a cryo-EM study suggests that chemically denatured actin interacts with only two TRiC subunits (delta and either beta or epsilon), actin and luciferase chains photocross-link to at least six TRiC subunits (alpha, beta, delta, epsilon, xi, and theta) at different stages of translation. Furthermore, the photocross-linking of actin, but not luciferase, nascent chains to TRiC subunits zeta and theta was length-dependent. In addition, a single photoreactive probe incorporated at a unique site in actin nascent chains of different lengths reacted covalently with multiple TRiC subunits, thereby indicating that the nascent chain samples the polypeptide binding sites of different subunits. We conclude that elongating actin and luciferase nascent chains contact multiple TRiC subunits upon emerging from the ribosome, and that the TRiC subunits contacted by nascent actin change as it elongates and starts to fold.

Item Type: Article
Additional information: PMID: 15929940
Subjects: Q Science
Divisions: Faculties > Science Technology and Medical Studies > School of Biosciences
Depositing User: Martin Carden
Date Deposited: 02 Oct 2009 17:44
Last Modified: 06 Sep 2011 04:27
Resource URI: http://kar.kent.ac.uk/id/eprint/22875 (The current URI for this page, for reference purposes)
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