The class II aminoacyl-tRNA synthetases and their active site: evolutionary conservation of an ATP binding site.
Previous sequence analyses have suggested the existence of two distinct classes of aminoacyl-tRNA synthetase. The partition was established on the basis of exclusive sets of sequence motifs (Eriani et al. [1990] Nature 347:203-306). X-ray studies have now well defined the structural basis of the two classes: the class I enzymes share with dehydrogenases and kinases the classic nucleotide binding fold called the Rossmann fold, whereas the class II enzymes possess a different fold, not found elsewhere, built around a six-stranded antiparallel beta-sheet. The two classes of synthetases catalyze the same global reaction that is the attachment of an amino acid to the tRNA, but differ as to where on the terminal adenosine of the tRNA the amino acid is placed: class I enzymes act on the 2' hydroxyl whereas the class II enzymes prefer the 3' hydroxyl group. The three-dimensional structure of aspartyl-tRNA synthetase from yeast, a typical class II enzyme, is described here, in relation to its function. The crucial role of the sequence motifs in substrate binding and enzyme structure is high-lighted. Overall these results underline the existence of an intimate evolutionary link between the aminoacyl-tRNA synthetases, despite their actual structural diversity.
Eriani
G
G
UPR 9002, Structure des Macromolécules Biologiques et Mécanismes de Reconnaissance, Institut de Biologie Moléculaire et Cellulaire du CNRS, Strasbourg, France.
Cavarelli
J
J
Martin
F
F
Ador
L
L
Rees
B
B
Thierry
J C
JC
Gangloff
J
J
Moras
D
D
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000495:Allosteric Site; D000595:Amino Acid Sequence; D000604:Amino Acyl-tRNA Synthetases / Q000737:chemistry* / Q000145:classification / Q000378:metabolism; D001226:Aspartate-tRNA Ligase / Q000737:chemistry / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry; D001665:Binding Sites; D005075:Biological Evolution; D016384:Consensus Sequence; D005656:Fungal Proteins / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D011487:Protein Conformation; D012343:RNA, Transfer / Q000378:metabolism; D012349:RNA, Transfer, Asp / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013329:Structure-Activity Relationship
D001426:Bacterial Proteins; D005656:Fungal Proteins; D012349:RNA, Transfer, Asp; D000255:Adenosine Triphosphate; D012343:RNA, Transfer; D000604:Amino Acyl-tRNA Synthetases; D001226:Aspartate-tRNA Ligase