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Structural disorder serves as a weak signal for intracellular protein degradation
Author(s) -
Tompa P.,
Prilusky J.,
Silman I.,
Sussman J. L.
Publication year - 2007
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.21773
Subject(s) - intrinsically disordered proteins , protein degradation , proteolysis , proteome , ubiquitin , degradation (telecommunications) , biology , computational biology , biophysics , microbiology and biotechnology , chemistry , biochemistry , computer science , enzyme , gene , telecommunications
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. Proteins 2008. © 2007 Wiley‐Liss, Inc.