Evolution of a signalling system that incorporates both redundancy and diversity:ArabidopsisSUMOylation

Abstract

The reversible post-translational modifier, SUMO (small ubiquitin-related modifier), modulates the activity of a diverse set of target proteins, resulting in important consequences to the cellular machinery. Conjugation machinery charges the processed SUMO so that it can be linked via an isopeptide bond to a target protein. The removal of SUMO moieties from conjugated proteins by isopeptidases regenerates pools of processed SUMOs and unmodified target proteins. The evolutionarily conserved SUMO-conjugating proteins, E1 and E2, recognize a diverse set of Arabidopsis SUMO proteins using them to modify protein substrates. In contrast, the deSUMOylating enzymes differentially recognize the Arabidopsis SUMO proteins, resulting in specificity of the deconjugating machinery. The specificity of the Arabidopsis deSUMOylating enzymes is further diversified by the addition of regulatory domains. Therefore the SUMO proteins, in this signalling system, have evolved to contain information that allows not only redundancy with the conjugation system but also diversity with the deconjugating enzymes.

Structural Analysis of Xanthomonas XopD Provides Insights into Substrate Specificity of Ubiquitin-like Protein Proteases

“…Recently, we reported the characterization of several SUMOs and ULPs from A. thaliana and demonstrated that ULP1 shows varying specificity for AtSUMO-1, -2, -3, and -5 as well as for M-SUMO-1, -2, and -4 and yeast SUMO (Smt3) (14). Sequence comparisons of these SUMOs and T-SUMO revealed a striking similarity (83% sequence identity) among AtSUMO-1, AtSUMO-2, and T-SUMO (supplemental Fig.…”

“…In Vitro Sumoylation Assays-In vitro sumoylation of 35 Slabeled mammalian HA-RanGAP with GST-AtSUMO-1, GSTAtSUMO-2, GST-AtSUMO-3, GST-AtSUMO-5, GST-T-SUMO, GST-Smt3, GST-M-SUMO-1, GST-M-SUMO-2, and GST-M-SUMO-4 was performed as described previously (14,25). In vitro peptidase assays using these sumoylated RanGAP proteins were performed as described above.…”

“…A. thaliana SUMO (AtSUMO)-1, -2, -3, and -5; Smt3; and M-SUMO-1, -2, and -4 were cloned as described previously (14).…”

“…A. thaliana ESD4 (early in short days 4) was shown to act as a SUMO protease and is potentially involved in regulating time of flowering (13). Recently, we characterized four ULPs from A. thaliana and showed that these proteases exhibit substrate specificity both for the processing of SUMO and for the cleavage of SUMO conjugates (14).…”

Characterization of the UGA-recoding and SECIS-binding activities of SECIS-binding protein 2

“…First, a known drawback of bacterially expressed recombinant protein is the lack of eukaryotic post-translational modifications. In contrast, a variety of protein modifications have been described in RRL with examples that include phosphorylation, acetylation, glycosylation, ubiquitination, and isoprenylation (reviewed in 41 ) as well as sumoylation 42 and methylation. 43 The ability of RRL to REMSAs were performed with equimolar amounts of the in vitro translated proteins incubated with PHGPx SECIS RNA as described in Figure 3.…”