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Investigating the Effect of Chain Connectivity on the Folding of a Beta-Sheet Protein On and Off the Ribosome.

Published version
Peer-reviewed

Type

Article

Change log

Authors

Marsden, Andrew P 
Hollins, Jeffrey J 
O'Neill, Charles 
Ryzhov, Pavel 
Higson, Sally 

Abstract

Determining the relationship between protein folding pathways on and off the ribosome remains an important area of investigation in biology. Studies on isolated domains have shown that alteration of the separation of residues in a polypeptide chain, while maintaining their spatial contacts, may affect protein stability and folding pathway. Due to the vectorial emergence of the polypeptide chain from the ribosome, chain connectivity may have an important influence upon cotranslational folding. Using MATH, an all β-sandwich domain, we investigate whether the connectivity of residues and secondary structure elements is a key determinant of when cotranslational folding can occur on the ribosome. From Φ-value analysis, we show that the most structured region of the transition state for folding in MATH includes the N and C terminal strands, which are located adjacent to each other in the structure. However, arrest peptide force-profile assays show that wild-type MATH is able to fold cotranslationally, while some C-terminal residues remain sequestered in the ribosome, even when destabilized by 2-3 kcal mol-1. We show that, while this pattern of Φ-values is retained in two circular permutants in our studies of the isolated domains, one of these permutants can fold only when fully emerged from the ribosome. We propose that in the case of MATH, onset of cotranslational folding is determined by the ability to form a sufficiently stable folding nucleus involving both β-sheets, rather than by the location of the terminal strands in the ribosome tunnel.

Description

Keywords

Phi value, SecM, folding on the ribosome, immunoglobulin-like, protein folding, Kinetics, Models, Molecular, Protein Biosynthesis, Protein Conformation, beta-Strand, Protein Folding, Protein Stability, Protein Structure, Secondary, Ribosomes, Tumor Necrosis Factor Receptor-Associated Peptides and Proteins

Journal Title

J Mol Biol

Conference Name

Journal ISSN

0022-2836
1089-8638

Volume Title

430

Publisher

Elsevier BV
Sponsorship
Wellcome Trust (095195/Z/10/Z)