Structural attributes in the conjugation of Ubiquitin, SUMO and RUB to protein substrates

Abstract

Many cellular and secreted proteins are chemically modified after their translation is completed. The covalent linkage of a polypeptide chain (modifier) to a substrate protein is a special case of post-translational modification. In the late seventies it was observed that ubiquitin, a small modifier, marks short-lived proteins for degradation by the 26S proteasome. Over the last decade many other ubiquitin-related proteins were discovered and isolated. Attachment of polypeptide chains onto acceptor molecules became a common feature to regulate spatially and timely organized cellular pathways of proteins. This article focuses on the structures of the three modifiers: ubiquitin, RUB and SUMO and the cognate enzymes involved in these modification pathways. We have described the homologies and differences of these proteins and indicate salient topological hallmarks common to modifier-conjugating enzymes. This characterization will help in understanding these regulatory pathways and their similarities and differences in controlling protein fate, from protein degradation signals generated by polyubiquitination to functional modification brought about by RUB and SUMO conjugation.

The role of autophagy in age‐related macular degeneration

“…The UPP is a vital cellular system in removing damaged proteins caused by oxidative stress (Pickart ; Goettsch & Bayer ). UPP and lysosomal proteolysis (LPP) usually work independently from each other and have different substrate specificities (Shang & Taylor ).…”

The SUMO conjugation pathway in Populus: genomic analysis, tissue-specific and inducible SUMOylation and in vitro de-SUMOylation

“…Although these protein modifiers are activated and conjugated to their respective substrates through similar mechanisms, their functions differ widely depending on the tag and the substrate protein. Some of the well-characterized tags include ubiquitin (Ub), Nedd8, Apg12 and the small ubiquitin-like modifier or SUMO (Vierstra and Callis 1999;Hay 2001;Goettsch and Bayer 2002).…”

Expression and purification of SARS coronavirus proteins using SUMO-fusions

“…Yeast SUMO shares 47% sequence identity with mammalian SUMO-1. Although overall sequence identity between ubiquitin and SUMO is only 18%, structure determination by NMR reveals that they share a common three-dimensional structure characterized by a tightly packed globular fold with -sheets wrapped around a single -helix [24,25]. It is known that SUMO, fused at the N-terminus with other proteins, can fold and protect the protein by its chaperoning properties, making it a useful tag for heterologous expression [26].…”