Jul 29, 2010

Homologs of aminoacyl-tRNA synthetases acylate carrier proteins and provide a link between ribosomal and nonribosomal peptide synthesis

Proceedings of the National Academy of Sciences of the United States of America
Marko MocibobIvana Weygand-Durasevic

Abstract

Aminoacyl-tRNA synthetases (aaRSs) are ancient and evolutionary conserved enzymes catalyzing the formation of aminoacyl-tRNAs, that are used as substrates for ribosomal protein biosynthesis. In addition to full length aaRS genes, genomes of many organisms are sprinkled with truncated genes encoding single-domain aaRS-like proteins, which often have relinquished their canonical role in genetic code translation. We have identified the genes for putative seryl-tRNA synthetase homologs widespread in bacterial genomes and characterized three of them biochemically and structurally. The proteins encoded are homologous to the catalytic domain of highly diverged, atypical seryl-tRNA synthetases (aSerRSs) found only in methanogenic archaea and are deprived of the tRNA-binding domain. Remarkably, in comparison to SerRSs, aSerRS homologs display different and relaxed amino acid specificity. aSerRS homologs lack canonical tRNA aminoacylating activity and instead transfer activated amino acid to phosphopantetheine prosthetic group of putative carrier proteins, whose genes were identified in the genomic surroundings of aSerRS homologs. Detailed kinetic analysis confirmed that aSerRS homologs aminoacylate these carrier proteins efficiently and...Continue Reading

Mentioned in this Paper

Amino Acid Activation, Translational
Bacterial Proteins
Genome
Enzymes, antithrombotic
Agrobacterium tumefaciens
MT-TA gene
Tertiary Protein Structure
Triplet Codon-amino Acid Adaptor Activity
Homologous Sequences, Amino Acid
Crystallography, X-Ray

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