Ubiquitin-related modifier Urm1 acts as a sulphur carrier in thiolation of eukaryotic transfer RNA

This paper shows that the yeast ubiquitin-like protein Urm1p is a sulphur carrier that modifies tRNA. It identifies a pathway whereby Urm1p is first adenylated by Uba4p, then is subsequently thiolated by Uba4p, after which the sulphur moiety is transferred from the thiolated Urm1p onto U34 of a cytoplasmic adenylated tRNA.