ABSTRACT
PACE08 (COG1369) polypeptides are a subunit o f Ribonuclease P, a complex required for
tRNA maturation that comprises four subunits in archaea and nine in eukaryotes (see chapter by Mitchell and Li in this volume). PACE18 (COG1041) proteins were shown to (di)methylate guanosine at position 10 o f tRNAs.19 They were called Trm-GlO (archaea)/Trml 1 (eukaryotes). Paralogs were identified in Pyrococci but their functions have not yet been investigated. Three PACE groups are involved in the complex modification o f phenylalanine tRNA at position 37, namely wyosine-derivatives biosynthesis (see chapter by Urbonavicius, Armengaud, Droogmans et al in this volume). The yeast proteins involved in this pathway, TYW I (PACE22, COG0731), TYW2 (PACE24, COG1590) and TYW3 (PACE25, COG2520) were recently characterized. The latter PACE group comprises also the Trm5 methyltransferase responsible for m lG methylation at position 37 of tRNAs in Archaea and Eukarya.
