LAUSR

Significance N-degron pathways target proteins for degradation by recognizing their N-terminal residues. A destabilizing N-terminal Arg residue can be generated by a proteolytic cleavage of a protein either directly or after N-terminal arginylation of the resulting C-terminal fragment by the Ate1 arginyl-tRNA-protein transferase (R-transferase). A three-dimensional structure of Ate1 is unknown. We describe here the crystal structure of the Ate1 R-transferase from the yeast Kluyveromyces lactis. We also describe results of enzymatic and functional assays with wild-type Ate1 and its mutants to address specific structural findings. These and related results advance the understanding of R-transferase and the Arg/N-degron pathway.