Structural analysis, supported by biochemical, mutagenesis and computational evidence, indicates that the peptidyltransferase centre of the contemporary ribosome is a universal symmetrical pocket composed solely of rRNA. This pocket seems to be a relic of the proto-ribosome, an ancient ribozyme, which was a dimeric RNA assembly formed from self-folded RNA chains of identical, similar or different sequences. This could have occurred spontaneously by gene duplication or gene fusion. This pocket-like entity was capable of autonomously catalysing various reactions, including peptide bond formation and non-coded or semi-coded amino acid polymerization. Efforts toward the structural definition of the early entity capable of genetic decoding involve the crystallization of the small ribosomal subunit of a bacterial organism harbouring a single functional rRNA operon.
Ancient machinery embedded in the contemporary ribosome
Matthew J. Belousoff, Chen Davidovich, Ella Zimmerman, Yaron Caspi, Itai Wekselman, Lin Rozenszajn, Tal Shapira, Ofir Sade-Falk, Leena Taha, Anat Bashan, Manfred S. Weiss, Ada Yonath; Ancient machinery embedded in the contemporary ribosome. Biochem Soc Trans 1 April 2010; 38 (2): 422–427. doi: https://doi.org/10.1042/BST0380422
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