Title: A SIM-ultaneous role for SUMO and ubiquitin
Abstract: Ubiquitin and ubiquitin-like proteins (Ubls) share a β-GRASP fold and have key roles in cellular growth and suppression of genome instability. Despite their common fold, SUMO and ubiquitin are classically portrayed as distinct, and they can have antagonistic roles. Recently, a new family of proteins, the small ubiquitin-related modifier (SUMO)-targeted ubiquitin ligases (STUbLs), which directly connect sumoylation and ubiquitylation, has been discovered. Uniquely, STUbLs use SUMO-interaction motifs (SIMs) to recognize their sumoylated targets. STUbLs are global regulators of protein sumoylation levels, and cells lacking STUbLs display genomic instability and hypersensitivity to genotoxic stress. The human STUbL, RNF4, is implicated in several diseases including cancer, highlighting the importance of characterizing the cellular functions of STUbLs. Ubiquitin and ubiquitin-like proteins (Ubls) share a β-GRASP fold and have key roles in cellular growth and suppression of genome instability. Despite their common fold, SUMO and ubiquitin are classically portrayed as distinct, and they can have antagonistic roles. Recently, a new family of proteins, the small ubiquitin-related modifier (SUMO)-targeted ubiquitin ligases (STUbLs), which directly connect sumoylation and ubiquitylation, has been discovered. Uniquely, STUbLs use SUMO-interaction motifs (SIMs) to recognize their sumoylated targets. STUbLs are global regulators of protein sumoylation levels, and cells lacking STUbLs display genomic instability and hypersensitivity to genotoxic stress. The human STUbL, RNF4, is implicated in several diseases including cancer, highlighting the importance of characterizing the cellular functions of STUbLs. an E1-activating enzyme (with ATP) adenylates the C-terminal carboxyl group of ubiquitin or Ubl, which forms a high-energy ubiquitin–AMP or Ubl–AMP intermediate. This intermediate is then attacked by the E1 active-site cysteine, forming an E1-ubiquitin or E1-Ubl thioester. The activated ubiquitin or Ubl is transferred to the active-site cysteine of the E2-conjugating enzyme. The ubiquitin or Ubl moiety is then ligated to an acceptor lysine in a target protein in a process stimulated by an E3 ligase, for example, the RING finger protein. this fold is built from a domain in which the β-sheet seems to 'grasp' its helical segment, and hence was named β-GRASP. This fold was first recognized in ubiquitin- and immunoglobulin-binding domains of Gram-positive bacteria and is now observed in other polypeptides, including the ubiquitin-like proteins. mediate the non-covalent interactions of SIM-containing proteins with SUMO. SIMs are typically short hydrophobic peptide sequences that, in some cases, are preceded, or followed, by a stretch of acidic amino acids. a new class of ubiquitin ligases that are targeted to, and ubiquitylate, sumoylated proteins. a family of proteins that includes SUMO, ISG15 (interferon-stimulated gene 15) and Nedd8 (neural precursor cell expressed developmentally downregulated 8), which are covalently attached to target proteins to modify their functions by promoting new interactions, altered localization or degradation. enzymes required for both the C-terminal processing 'maturation' of SUMO and its removal from target proteins.
Publication Year: 2008
Publication Date: 2008-05-01
Language: en
Type: review
Indexed In: ['crossref', 'pubmed']
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Cited By Count: 215
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