A Novel SUMO1-specific Interacting Motif in Dipeptidyl Peptidase 9 (DPP9) That Is Important for Enzymatic Regulation

• Published in: The Journal of biological chemistry Vol. 287; no. 53; pp. 44320 - 44329
• Main Authors: Pilla, Esther, Möller, Ulrike, Sauer, Guido, Mattiroli, Francesca, Melchior, Frauke, Geiss-Friedlander, Ruth
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 28-12-2012; American Society for Biochemistry and Molecular Biology
• Subjects: Amino Acid Motifs; Amino Acid Sequence; Binding Sites; Dipeptidyl Peptidase; Dipeptidyl-Peptidases and Tripeptidyl-Peptidases - chemistry; Dipeptidyl-Peptidases and Tripeptidyl-Peptidases - genetics; Dipeptidyl-Peptidases and Tripeptidyl-Peptidases - metabolism; Gene Expression Regulation, Enzymologic; HeLa Cells; Humans; Kinetics; Molecular Sequence Data; Peptidases; Post-translational Modification; Protease; Protein Binding; Protein Synthesis and Degradation; SUMO; SUMO-1 Protein - chemistry; SUMO-1 Protein - genetics; SUMO-1 Protein - metabolism; SUMO-interacting Motif (SIM); Sumoylation; Ubiquitin; Ubiquitin; Peptidases; SUMO; Post-translational Modification; Protease; SUMO-interacting Motif (SIM); Sumoylation; Dipeptidyl Peptidase
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M112.397224

Sumoylation affects many cellular processes by regulating the interactions of modified targets with downstream effectors. Here we identified the cytosolic dipeptidyl peptidase 9 (DPP9) as a SUMO1 interacting protein. Surprisingly, DPP9 binds to SUMO1 independent of the well known SUMO interacting motif, but instead interacts with a loop involving Glu67 of SUMO1. Intriguingly, DPP9 selectively associates with SUMO1 and not SUMO2, due to a more positive charge in the SUMO1-loop. We mapped the SUMO-binding site of DPP9 to an extended arm structure, predicted to directly flank the substrate entry site. Importantly, whereas mutants in the SUMO1-binding arm are less active compared with wild-type DPP9, SUMO1 stimulates DPP9 activity. Consistent with this, silencing of SUMO1 leads to a reduced cytosolic prolyl-peptidase activity. Taken together, these results suggest that SUMO1, or more likely, a sumoylated protein, acts as an allosteric regulator of DPP9.
Interactions of SUMO isoforms/paralogs involve a groove on SUMO1–3 and a SIM on the downstream effector.
A novel motif in DPP9 binds to a loop on SUMO1, leading to allosteric activation of DPP9.
The SUMO1-loop is an additional surface for noncovalent interactions, allowing discrimination between SUMO1–3.
Learning how SUMO isoforms/paralogs are recognized advances our understanding on events downstream of sumoylation.