The size of the proteasomal substrate determines whether its degradation will be mediated by mono- or polyubiquitylation

Item Type:	Article
Title:	The size of the proteasomal substrate determines whether its degradation will be mediated by mono- or polyubiquitylation
Creators Name:	Shabek, N. and Herman-Bachinsky, Y. and Buchsbaum, S. and Lewinson, O. and Haj-Yahya, M. and Hejjaoui, M. and Lashuel, H.A. and Sommer, T. and Brik, A. and Ciechanover, A.
Abstract:	A polyubiquitin chain anchored to the substrate has been the hallmark of proteasomal recognition. However, the degradation signal appears to be more complex and to contain also a substrate's unstructured region. Recent reports have shown that the proteasome can degrade also monoubiquitylated proteins, which adds an additional layer of complexity to the signal. Here, we demonstrate that the size of the substrate is an important determinant in its extent of ubiquitylation: a single ubiquitin moiety fused to a tail of up to ∼150 residues derived from either short artificial repeats or from naturally occurring proteins, is sufficient to target them for proteasomal degradation. Importantly, chemically synthesized adducts, where ubiquitin is attached to the substrate via a naturally occurring isopeptide bond, display similar characteristics. Taken together, these findings suggest that the ubiquitin proteasomal signal is adaptive, and is not always made of a long polyubiquitin chain.
Keywords:	Amino Acid Repetitive Sequences, Amino Acid Sequence, Green Fluorescent Proteins, HEK293 Cells, Molecular Models, Molecular Sequence Data, Peptides, Polyubiquitin, Proteasome Endopeptidase Complex, Recombinant Fusion Proteins, Substrate Specificity, Ubiquitin, Ubiquitination
Source:	Molecular Cell
ISSN:	1097-2765
Publisher:	Cell Press
Volume:	48
Number:	1
Page Range:	87-97
Date:	12 October 2012
Official Publication:	https://doi.org/10.1016/j.molcel.2012.07.011
PubMed:	View item in PubMed

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