An "up" oriented methionine-aromatic structural motif in SUMO is critical for its stability and activity

J Biol Chem. 2021 Aug;297(2):100970. doi: 10.1016/j.jbc.2021.100970. Epub 2021 Jul 15.


Protein structural bioinformatic analyses suggest preferential associations between methionine and aromatic amino acid residues in proteins. Ab initio energy calculations highlight a conformation-dependent stabilizing interaction between the interacting sulfur-aromatic molecular pair. However, the relevance of buried methionine-aromatic motifs to protein folding and function is relatively unexplored. The Small Ubiquitin-Like Modifier (SUMO) is a β-grasp fold protein and a common posttranslational modifier that affects diverse cellular processes, including transcriptional regulation, chromatin remodeling, metabolic regulation, mitosis, and meiosis. SUMO is a member of the Ubiquitin-Like (UBL) protein family. Herein, we report that a highly conserved and buried methionine-phenylalanine motif is a unique signature of SUMO proteins but absent in other homologous UBL proteins. We also detect that a specific "up" conformation between the methionine-phenylalanine pair of interacting residues in SUMO is critical to its β-grasp fold. The noncovalent interactions of SUMO with its ligands are dependent on the methionine-phenylalanine pair. MD simulations, NMR, and biophysical and biochemical studies suggest that perturbation of the methionine-aromatic motif disrupts native contacts, modulates noncovalent interactions, and attenuates SUMOylation activity. Our results highlight the importance of conserved orientations of Met-aromatic structural motifs inside a protein core for its structure and function.

Keywords: SUMO-interacting motif (SIM); SUMOylation; methionine-aromatic motifs; structure-function; sulfur-aromatic interaction.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Amino Acid Sequence
  • Humans
  • Methionine / chemistry*
  • Molecular Dynamics Simulation*
  • Phenylalanine / chemistry*
  • Protein Folding
  • Protein Interaction Domains and Motifs*
  • Protein Stability
  • SUMO-1 Protein / chemistry*
  • SUMO-1 Protein / metabolism
  • Structure-Activity Relationship
  • Sumoylation*


  • SUMO-1 Protein
  • Phenylalanine
  • Methionine