Modern diversification of the amino acid repertoire driven by oxygen.

Autor:	Granold M; Evolutionary Biochemistry and Redox Medicine, Institute for Pathobiochemistry, University Medical Center of the Johannes Gutenberg University, 55128 Mainz, Germany., Hajieva P; Cellular Adaptation Group, Institute for Pathobiochemistry, University Medical Center of the Johannes Gutenberg University, 55128 Mainz, Germany., Toşa MI; Group of Biocatalysis and Biotransformations, Faculty of Chemistry and Chemical Engineering, Babeş-Bolyai University, Cluj-Napoca 400028, Romania., Irimie FD; Group of Biocatalysis and Biotransformations, Faculty of Chemistry and Chemical Engineering, Babeş-Bolyai University, Cluj-Napoca 400028, Romania., Moosmann B; Evolutionary Biochemistry and Redox Medicine, Institute for Pathobiochemistry, University Medical Center of the Johannes Gutenberg University, 55128 Mainz, Germany; moosmann@uni-mainz.de.
Jazyk:	angličtina
Zdroj:	Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 2018 Jan 02; Vol. 115 (1), pp. 41-46. Date of Electronic Publication: 2017 Dec 19.
DOI:	10.1073/pnas.1717100115
Abstrakt:	All extant life employs the same 20 amino acids for protein biosynthesis. Studies on the number of amino acids necessary to produce a foldable and catalytically active polypeptide have shown that a basis set of 7-13 amino acids is sufficient to build major structural elements of modern proteins. Hence, the reasons for the evolutionary selection of the current 20 amino acids out of a much larger available pool have remained elusive. Here, we have analyzed the quantum chemistry of all proteinogenic and various prebiotic amino acids. We find that the energetic HOMO-LUMO gap, a correlate of chemical reactivity, becomes incrementally closer in modern amino acids, reaching the level of specialized redox cofactors in the late amino acids tryptophan and selenocysteine. We show that the arising prediction of a higher reactivity of the more recently added amino acids is correct as regards various free radicals, particularly oxygen-derived peroxyl radicals. Moreover, we demonstrate an immediate survival benefit conferred by the enhanced redox reactivity of the modern amino acids tyrosine and tryptophan in oxidatively stressed cells. Our data indicate that in demanding building blocks with more versatile redox chemistry, biospheric molecular oxygen triggered the selective fixation of the last amino acids in the genetic code. Thus, functional rather than structural amino acid properties were decisive during the finalization of the universal genetic code. Competing Interests: Conflict of interest statement: Some of the chemical compounds used in this work have been patented by the Max Planck Society, naming author B.M. as one of the inventors (EP 1113795 B1).
Databáze:	MEDLINE
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