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

Autor: Marsden AP; Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK., Hollins JJ; Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK., O'Neill C; Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK., Ryzhov P; Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK., Higson S; Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK., Mendonça CATF; Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK., Kwan TO; Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK., Kwa LG; Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK., Steward A; Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK. Electronic address: as376@cam.ac.uk., Clarke J; Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK. Electronic address: jc162@cam.ac.uk.
Jazyk: angličtina
Zdroj: Journal of molecular biology [J Mol Biol] 2018 Dec 07; Vol. 430 (24), pp. 5207-5216. Date of Electronic Publication: 2018 Oct 23.
DOI: 10.1016/j.jmb.2018.10.011
Abstrakt: 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.
(Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.)
Databáze: MEDLINE
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