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Urm1 (Ubiquitin related modifier)
Ubiquitin related modifier-1 (2qjl). In the center of protein β-grasp fold is located. Additionally, carboxy terminal glycine within a di-glycine motif is marked blue, and Mg ions are represented by black spheres.
Identifiers
Symbol	URM1
Pfam	PF09138
InterPro	IPR015221
SCOP2	d.15.3.3 / SCOPe / SUPFAM
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary PDB 1wgk 1xo3 2ax5 2k9x 2k9x 2qjl

Ubiquitin-related modifier-1 (URM1) is a ubiquitin-like protein that modifies proteins in the yeast ubiquitin-like urmylation pathway. Structural comparisons and phylogenetic analysis of the ubiquitin superfamily has indicated that Urm1 has the most conserved structural and sequence features of the common ancestor of the entire superfamily.

Urm1 is characterized by a core β-grasp fold and an essential carboxy terminal glycine within a di-glycine motif. Urm1 is known to be conjugated to the peroxiredoxin Ahp1, ATPBD3, and CTU2 and human MOCS3, through a mechanism involving the E1-like protein Uba4 via lysine residues. Similar to ubiquitination, urmylation requires a thioester intermediate and forms isopeptide bonds between Urm1 and its substrates. Moreover, the urmylation process can be significantly enhanced by oxidative stress. Functions as a protein tag with roles in nutrient sensing and oxidative stress response.

Recently it has been demonstrated that Urm1 can acts as a sulfur carrier in the thiolation of eukaryotic tRNA via a mechanism that requires the formation of a thiocarboxylated Urm1. URM1 is involved in thiolation of cytoplasmic tRNAs; receives sulfur from the E1-like enzyme Uba4 and transfers it to tRNA. Sequence and structural homology studies suggest that Urm1 can be more closely linked to the prokaryotic sulphur transfer proteins, ThiS and MoaD, that can be considered as prokaryotic counterparts of the eukaryotic UBls.

See also

• Ubiquitin

References

1. Goehring AS, Rivers DM, Sprague GF (November 2003). "Urmylation: a ubiquitin-like pathway that functions during invasive growth and budding in yeast". Molecular Biology of the Cell. 14 (11): 4329–41. doi:10.1091/mbc.E03-02-0079. PMC 266754. PMID 14551258.
2. Xu J, Zhang J, Wang L, Zhou J, Huang H, Wu J, Zhong Y, Shi Y (August 2006). "Solution structure of Urm1 and its implications for the origin of protein modifiers". Proceedings of the National Academy of Sciences of the United States of America. 103 (31): 11625–30. Bibcode:2006PNAS..10311625X. doi:10.1073/pnas.0604876103. PMC 1518799. PMID 16864801.
3. Goehring AS, Rivers DM, Sprague GF (November 2003). "Urmylation: a ubiquitin-like pathway that functions during invasive growth and budding in yeast". Molecular Biology of the Cell. 14 (11): 4329–41. doi:10.1091/mbc.E03-02-0079. PMC 266754. PMID 14551258.
4. Van der Veen AG, Schorpp K, Schlieker C, Buti L, Damon JR, Spooner E, Ploegh HL, Jentsch S (February 2011). "Role of the ubiquitin-like protein Urm1 as a noncanonical lysine-directed protein modifier". Proceedings of the National Academy of Sciences of the United States of America. 108 (5): 1763–70. doi:10.1073/pnas.1014402108. PMC 3033243. PMID 21209336.
5. Wang F, Liu M, Qiu R, Ji C (August 2011). "The dual role of ubiquitin-like protein Urm1 as a protein modifier and sulfur carrier". Protein & Cell. 2 (8): 612–9. doi:10.1007/s13238-011-1074-6. PMC 4875326. PMID 21904977.
6. Petroski MD, Salvesen GS, Wolf DA (February 2011). "Urm1 couples sulfur transfer to ubiquitin-like protein function in oxidative stress". Proceedings of the National Academy of Sciences of the United States of America. 108 (5): 1749–50. Bibcode:2011PNAS..108.1749P. doi:10.1073/pnas.1019043108. PMC 3033263. PMID 21245332.
7. Pedrioli PG, Leidel S, Hofmann K (December 2008). "Urm1 at the crossroad of modifications. 'Protein Modifications: Beyond the Usual Suspects' Review Series". EMBO Reports. 9 (12): 1196–202. doi:10.1038/embor.2008.209. PMC 2603462. PMID 19047990.

• Post-translational modification
• Proteins