SUMO chain formation relies on the amino-terminal region of SUMO-conjugating enzyme and has dedicated substrates in plants
نویسندگان
چکیده
The small ubiquitin-related modifier (SUMO) conjugation apparatus usually attaches single SUMO moieties to its substrates, but SUMO chains have also been identified. To better define the biochemical requirements and characteristics of SUMO chain formation, mutations in surface-exposed Lys residues of Arabidopsis SUMO-conjugating enzyme (SCE) were tested for in vitro activity. Lys-to-Arg changes in the amino-terminal region of SCE allowed SUMO acceptance from SUMO-activating enzyme and supported substrate mono-sumoylation, but these mutations had significant effects on SUMO chain assembly. We found no indication that SUMO modification of SCE promotes chain formation. A substrate was identified that is modified by SUMO chain addition, showing that SCE can distinguish substrates for either mono-sumoylation or SUMO chain attachment. It is also shown that SCE with active site Cys mutated to Ser can accept SUMO to form an oxyester, but cannot transfer this SUMO moiety onto substrates, explaining a previously known dominant negative effect of this mutation.
منابع مشابه
Observation of an E2 (Ubc9)-homodimer by crystallography
Post-translational modifications by the small ubiquitin-like modifiers (SUMO), in particular the formation of poly-SUMO-2 and -3 chains, regulates essential cellular functions and its aberration leads to life-threatening diseases (Geoffroy and Hay, 2009) [1]. It was shown previously that the non-covalent interaction between SUMO and the conjugating enzyme (E2) for SUMO, known as Ubc9, is requir...
متن کاملArabidopsis PIAL1 and 2 promote SUMO chain formation as E4-type SUMO ligases and are involved in stress responses and sulfur metabolism.
The Arabidopsis thaliana genes PROTEIN INHIBITOR OF ACTIVATED STAT LIKE1 (PIAL1) and PIAL2 encode proteins with SP-RING domains, which occur in many ligases of the small ubiquitin-related modifier (SUMO) conjugation pathway. We show that PIAL1 and PIAL2 function as SUMO ligases capable of SUMO chain formation and require the SUMO-modified SUMO-conjugating enzyme SCE1 for optimal activity. Mutan...
متن کاملUbe2W conjugates ubiquitin to α-amino groups of protein N-termini
The covalent attachment of the protein ubiquitin to intracellular proteins by a process known as ubiquitylation regulates almost all major cellular systems, predominantly by regulating protein turnover. Ubiquitylation requires the co-ordinated action of three enzymes termed E1, E2 and E3, and typically results in the formation of an isopeptide bond between the C-terminal carboxy group of ubiqui...
متن کاملSmall ubiquitin-like modifier modulates abscisic acid signaling in Arabidopsis.
Post-translational modification of proteins by small polypeptides, such as ubiquitin, has emerged as a common and important mechanism for regulating protein function. Small ubiquitin-like modifier (SUMO) is a small protein that is structurally related to but functionally different from ubiquitin. We report the identification and functional analysis of AtSUMO1, AtSUMO2, and AtSCE1a as components...
متن کاملUbc9 acetylation: a new route for achieving specificity in substrate SUMOylation.
In contrast to the dozens of proteins involved in ubiquitination pathways, relatively few proteins control SUMO modification. Generating specificity and diversity in pathway outcomes may therefore rely on post-translational modification of pathway components and/or substrates. A new paper in The EMBO Journal identifies one such modification event, the acetylation of Ubc9, as a key regulatory st...
متن کامل