期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2003
卷号：100
期号：17
页码：9785-9790
DOI：10.1073/pnas.1733391100
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Proteins in the ATP-grasp superfamily of amide bond-forming ligases have evolved to function in a number of unrelated biosynthetic pathways. Previously identified homologs encoding glutathione synthetase, D-alanine:D-alanine ligase and the bacterial ribosomal protein S6:glutamate ligase have been vertically inherited within certain organismal lineages. Although members of this specificity-diverse superfamily share a common reaction mechanism, the nonoverlapping set of amino acid and peptide substrates recognized by each family provided few clues as to their evolutionary history. Two members of this family have been identified in the hyperthermophilic marine archaeon Methanococcus jannaschii and shown to catalyze the final reactions in two coenzyme biosynthetic pathways. The MJ0620 (mptN) locus encodes a tetrahydromethanopterin:-L-glutamate ligase that forms tetrahydrosarcinapterin, a single carbon-carrying coenzyme. The MJ1001 (cofF) locus encodes a {gamma}-F420-2:-L-glutamate ligase, which caps the {gamma}-glutamyl tail of the hydride carrier coenzyme F420. These two genes share a common ancestor with the ribosomal protein S6:glutamate ligase and a putative -aminoadipate ligase, defining the first group of ATP-grasp enzymes with a shared amino acid substrate specificity. As in glutathione biosynthesis, two unrelated amino acid ligases catalyze sequential reactions in coenzyme F420 polyglutamate formation: a {gamma}-glutamyl ligase adds 1-3 L-glutamate residues and the ATP-grasp-type ligase described here caps the chain with a single -linked L-glutamate residue. The analogous pathways for glutathione, F420, folate, and murein peptide biosyntheses illustrate convergent evolution of nonribosomal peptide biosynthesis through the recruitment of single-step amino acid ligases.
