AMINOACYL-TRANSFER-RNA SYNTHETASES

Crystallographic studies of a number of aminoacyl-tRNA synthetases and their complexes with ATP, amino acid and cognate tRNA are leading to an increasingly detailed picture of how these sophisticated enzymes fu nction. Within the two distinct structural classes of ten synthetases, many common features are apparent, although evolution has led to many interesting idiosyncrasies in certain enzymes. Recent advances, speci fically concerning class II enzymes, have increased our knowledge of b oth the role of electrophiles in the mechanism of amino acid activatio n and cross-subunit tRNA recognition and help solve the evolutionary p uzzles that have emerged from the extension of the aminoacyl-tRNA synt hetase database to include Archae. (C) Current Biology Ltd ISSN 0959-4 40X.