Sulfur transfer and activation by ubiquitin-like modifier system Uba4•Urm1 link protein urmylation and tRNA thiolation in yeast

October 24, 2016

Urm1 is a unique dual-function member of the ubiquitin protein family and conserved from yeast to man. It acts both as a protein modifier in ubiquitin-like urmylation and as a sulfur donor for tRNA thiolation. We therefore studied whether Urm1 dual-functions may be interlinked by comparing both tRNA thiolation and urmylation under URM1 pathway inactivating conditions. We found that the two URM1 pathway branches, tRNA thiolation and protein urmylation, are chemically linked through sulfur supply, transfer and activation by the ubiquitin-like modifier system Uba4•Urm1