We want to understand, on a molecular level, how proteins and RNA recognize each other and how their interaction interface mediates specificity. To this end we study both apo-structures and RNA co-crystal structures of proteins involved in processing and modification of RNA. Most transcripts undergo processing and modification. Out of these, transfer RNA is by far the most studied and modification of tRNA has been the focus of our lab for several years. Recently, we have expanded into structural studies on the general process of mitochondrial RNA biogenesis: transcription, processing and modification.