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Sci Rep. 2016 Oct 4;6:34654. doi: 10.1038/srep34654.

Structural studies of the N-terminal fragments of the WW domain: Insights into co-translational folding of a beta-sheet protein.

Author information

1
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan.

Abstract

Nascent proteins fold co-translationally because the folding speed and folding pathways are limited by the rate of ribosome biosynthesis in the living cell. In addition, though full-length proteins can fold all their residues during the folding process, nascent proteins initially fold only with the N-terminal residues. However, the transient structure and the co-translational folding pathway are not well understood. Here we report the atomic structures of a series of N-terminal fragments of the WW domain with increasing amino acid length. Unexpectedly, the structures indicate that the intermediate-length fragments take helical conformations even though the full-length protein has no helical regions. The circular dichroism spectra and theoretical calculations also support the crystallographic results. This suggests that the short-range interactions are more decisive in the structure formation than the long-range interactions for short nascent proteins. In the course of the peptide extension, the helical structure change to the structure mediated by the long-range interactions at a particular polypeptide length. Our results will provide unique information for elucidating the nature of co-translational folding.

PMID:
27698466
PMCID:
PMC5048162
DOI:
10.1038/srep34654
[Indexed for MEDLINE]
Free PMC Article

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