Ubiquitin-related modifier-1 (URM1) is a
ubiquitin-like protein
Ubiquitin-like proteins (UBLs) are a family of small proteins involved in post-translational modification of other proteins in a cell, usually with a regulatory function. The UBL protein family derives its name from the first member of the class ...
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
Adenylyltransferase and sulfurtransferase MOCS3 is an enzyme that in humans is encoded by the ''MOCS3'' gene.
Molybdenum cofactor (MoCo) is necessary for the function of all molybdoenzymes. One of the enzymes required for the biosynthesis of MoC ...
, 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
Transfer RNA (abbreviated tRNA and formerly referred to as sRNA, for soluble RNA) is an adaptor molecule composed of RNA, typically 76 to 90 nucleotides in length (in eukaryotes), that serves as the physical link between the mRNA and the amino ...
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
Ubiquitin is a small (8.6 kDa) regulatory protein found in most tissues of eukaryotic organisms, i.e., it is found ''ubiquitously''. It was discovered in 1975 by Gideon Goldstein and further characterized throughout the late 1970s and 1980s. Fo ...
References
{{Posttranslational modification
Post-translational modification
Proteins