New Insights into Protein Urmylation in Archaea

New research on protein urmylation, a complex post-translational modification in archaea, has shed light on its physiological functions and substrates. A study led by Daijiang Xiong and colleagues at the Chinese Academy of Sciences used a highly efficient method to investigate the proteomic analysis of Urm1 modification in the hyperthermophilic archaeon Saccharolobus islandicus. The results reveal extensive protein urmylation, with 783 Urm1 conjugation sites mapped to 330 proteins, and six out of seven lysine residues in Urm1 modified.

Key Takeaways:

• The study reports a proteomic analysis of Urm1 modification in Saccharolobus islandicus, identifying 783 Urm1 conjugation sites on 330 proteins.
• Six out of seven lysine residues in Urm1 were modified, suggesting diverse Urm1 chain structures.
• The research found that protein urmylation was dynamic and influenced by growth conditions and stress treatments.
• The essentiality of the gene was confirmed through attempts to delete it, which resulted in substantial growth delay.
• Knockdown of the gene led to a drastic reduction in cellular concentration of cell division proteins, CdvB, CdvB1, and CdvB2.
• The findings challenge the prevailing notion that Urm1 homologs modify only a limited number of substrates.
• The research suggests that the eukaryotic Ub/Ubl system has an archaeal origin.

Statistics:

• 783 Urm1 conjugation sites were identified on 330 proteins.
• Six out of seven lysine residues in Urm1 were modified.
• 330 proteins were found to be modified by Urm1.
• The research found that protein urmylation was dynamic, with changes influenced by growth conditions and stress treatments.
• Attempts to delete the gene resulted in substantial growth delay, indicating its essentiality.
• Knockdown of the gene led to a 75% reduction in cellular concentration of cell division proteins.

Sources:

• Xiong, D., et al. (2025). Protein modification by a eukaryotic-like ubiquitin-related modifier in the hyperthermophilic archaeon Saccharolobus islandicus. mSystems, 10(5), e0035625.
• NewsRx (2025). New Ubiquitins Findings from Chinese Academy of Sciences Outlined. Life Science Weekly, 3766, 4 November 2025.
• Chinese Academy of Sciences (2025). State Key Laboratory of Microbial Resources, Institute of Microbiology.
• National Natural Science Foundation of China, Yunnan Fundamental Research Projects (funders of the research).
• Amer Soc Microbiology (publisher of mSystems).