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Topologies of a Substrate Protein Bound to the Chaperonin GroEL

Elad, Nadav and Farr, G.W. and Clare, Daniel K. and Orlova, Elena and Horwich, A.L. and Saibil, Helen (2007) Topologies of a Substrate Protein Bound to the Chaperonin GroEL. Molecular Cell 26 (3), 415 - 426. ISSN 1097-2765.

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The chaperonin GroEL assists polypeptide folding through sequential steps of binding nonnative protein in the central cavity of an open ring, via hydrophobic surfaces of its apical domains, followed by encapsulation in a hydrophilic cavity. To examine the binding state, we have classified a large data set of GroEL binary complexes with nonnative malate dehydrogenase (MDH), imaged by cryo-electron microscopy, to sort them into homogeneous subsets. The resulting electron density maps show MDH associated in several characteristic binding topologies either deep inside the cavity or at its inlet, contacting three to four consecutive GroEL apical domains. Consistent with visualization of bound polypeptide distributed over many parts of the central cavity, disulfide crosslinking could be carried out between a cysteine in a bound substrate protein and cysteines substituted anywhere inside GroEL. Finally, substrate binding induced adjustments in GroEL itself, observed mainly as clustering together of apical domains around sites of substrate binding.

Item Type: Article
Keyword(s) / Subject(s): Proteins
School or Research Centre: Birkbeck Schools and Research Centres > School of Science > Biological Sciences
Depositing User: Administrator
Date Deposited: 08 Aug 2011 10:26
Last Modified: 06 Oct 2016 10:16

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