Functional Class I and II Amino Acid-activating Enzymes Can Be Coded by Opposite Strands of the Same Gene.
Aminoacyl-tRNA synthetases (aaRS) catalyze both chemical steps that translate the universal genetic code. Rodin and Ohno offered an explanation for the existence of two aaRS classes, observing that codons for the most highly conserved Class I active-site residues are anticodons for corresponding Class II active-site residues. They proposed that the two classes arose simultaneously, by translation of opposite strands from the same gene. We have characterized wild-type 46-residue peptides containing ATP-binding sites of Class I and II synthetases and those coded by a gene designed by Rosetta to encode the corresponding peptides on opposite strands. Catalysis by WT and designed peptides is saturable, and the designed peptides are sensitive to active-site residue mutation. All have comparable apparent second-order rate constants 2.9-7.0E-3 M(-1) s(-1) or ∼750,000-1,300,000 times the uncatalyzed rate. The activities of the two complementary peptides demonstrate that the unique information in a gene can have two functional interpretations, one from each complementary strand. The peptides contain phylogenetic signatures of longer, more sophisticated catalysts we call Urzymes and are short enough to bridge the gap between them and simpler uncoded peptides. Thus, they directly substantiate the sense/antisense coding ancestry of Class I and II aaRS. Furthermore, designed 46-mers achieve similar catalytic proficiency to wild-type 46-mers by significant increases in both kcat and Km values, supporting suggestions that the earliest peptide catalysts activated ATP for biosynthetic purposes.
['Martinez-Rodriguez|Luis|L|', 'Erdogan|Ozgün|O|', 'Jimenez-Rodriguez|Mariel|M|', 'Gonzalez-Rivera|Katiria|K|', 'Williams|Tishan|T|', 'Li|Li|L|', 'Weinreb|Violetta|V|', 'Collier|Martha|M|', 'Chandrasekaran|Srinivas Niranj|SN|', 'Ambroggio|Xavier|X|', 'Kuhlman|Brian|B|', 'Carter|Charles W|CW|']
D000255:Adenosine Triphosphate D000595:Amino Acid Sequence D000604:Amino Acyl-tRNA Synthetases D049148:Aminoacylation D055162:Biocatalysis D020134:Catalytic Domain D003062:Codon D004926:Escherichia coli D019143:Evolution, Molecular D015870:Gene Expression D005815:Genetic Code D007700:Kinetics D008969:Molecular Sequence Data D009154:Mutation D010455:Peptides D011485:Protein Binding D011994:Recombinant Proteins
ATP Rodin-Ohno hypothesis amino acid activation aminoacyl tRNA synthetase chemical biology enzyme catalysis gene structure origin of life protein design sense/antisense genetic coding