Structural disorder serves as a weak signal for intracellular protein degradation.

TitleStructural disorder serves as a weak signal for intracellular protein degradation.
Publication TypeJournal Article
Year of Publication2008
AuthorsTompa, P., J. Prilusky, I. Silman, and J. L. Sussman
JournalProteins
Volume71
Issue2
Pagination903-9
Date Published2008 May 1
Type of Articleidp
ISSN1097-0134
KeywordsAlgorithms, Amino Acid Motifs, Half-Life, Molecular Weight, Peptide Hydrolases, Protein Structure, Secondary, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins
Abstract

Targeted turnover of proteins is a key element in the regulation of practically all basic cellular processes. The underlying physicochemical and/or sequential signals, however, are not fully understood. This issue is particularly pertinent in light of the recent recognition that intrinsically unstructured/disordered proteins, common in eukaryotic cells, are extremely susceptible to proteolytic degradation in vitro. The in vivo half-lives of proteins were determined recently in a high-throughput study encompassing the entire yeast proteome; here we examine whether these half-lives correlate with the presence of classical degradation motifs (PEST region, destruction-box, KEN-box, or the N-terminal residue) or with various physicochemical characteristics, such as the size of the protein, the degree of structural disorder, or the presence of low-complexity regions. Our principal finding is that, in general, the half-life of a protein does not depend on the presence of degradation signals within its sequence, even of ubiquitination sites, but correlates mainly with the length of its polypeptide chain and with various measures of structural disorder. Two distinct modes of involvement of disorder in degradation are proposed. Susceptibility to degradation of longer proteins, containing larger numbers of residues in conformational disorder, suggests an extensive function, whereby the effect of disorder can be ascribed to its mere physical presence. However, after normalization for protein length, the only signal that correlates with half-life is disorder, which indicates that it also acts in an intensive manner, that is, as a specific signal, perhaps in conjunction with the recognition of classical degradation motifs. The significance of correlation is rather low; thus protein degradation is not determined by a single characteristic, but is a multi-factorial process that shows large protein-to-protein variations. Protein disorder, nevertheless, plays a key signalling role in many cases.

DOI10.1002/prot.21773
Alternate JournalProteins
PubMed ID18004785
Grant ListAS1324 / / Autism Speaks / United States
ISRF 067595 / / Wellcome Trust / United Kingdom