Partition of tRNA synthetases into two classes based on mutually exclusive sets of sequence motifs

摘要: The aminoacyl-transfer RNA synthetases (aaRS) catalyse the attachment of an amino acid to its cognate transfer molecule in a highly specific two-step reaction. These proteins differ widely size and oligomeric state, have limited sequence homology. Out 18 known aaRS, only 9 referred as class I (GlnRS, TyrRS, MetRS, GluRS, ArgRS, ValRS, IleRS, LeuRS, TrpRS), display two short common consensus sequences ('HIGH' 'KMSKS') which indicate, observed three crystal structures, presence structural domain (the Rossman fold) that binds ATP. We report here Escherichia coli ProRS, dimer relative molecular mass 127,402, is homologous both ThrRS SerRS. latter aaRS share new motifs with AspRS, AsnRS, LysRS, HisRS beta subunit PheRS. (motifs 1, 2 3), search through entire data bank, proved be for this set (referred II). Class II may also contain AlaRS GlyRS, because these typical motif 3. Surprisingly, partition classes found strongly correlated on functional level acylation occurring either 2' OH (class I) or 3' II) ribose last nucleotide tRNA.