The evolution of the ribosome, illustrating growth of the large (LSU) and small (SSU) subunits, separately at first and eventually as parts of a whole

The evolution of the ribosome, illustrating growth of the large (LSU) and small (SSU) subunits, separately at first and eventually as parts of a whole

In Phase 1, ancestral RNAs form stem loops and minihelices. In Phase 2, LSU, which has a short tunnel, condenses short, nonspecific, peptide-like oligomers. Some of these oligomers bind back onto the ribosome and stabilize it. At this point, SSU may have a single-stranded RNA-binding function. In Phase 3, the subunits associate, mediated by the expansion of tRNA from a minihelix to its modern L-shape. The tunnel elongates. LSU and SSU evolution is independent and uncorrelated during phases 1-3.

In Phase 4, the two subunits associate and their evolution is correlated. The ribosome is a noncoding diffusive ribozyme in which proto-mRNA and the SSU act as positioning cofactors, producing peptide-like oligomers, some of which form beta-hairpins. In Phase 5, the ribosome expands to an energy-driven, translocating, decoding machine. Phase 6 marks completion of the common core with a proteinized surface (the proteins are omitted for clarity). mRNA is shown in light green. The A-site tRNA is magenta, the P-site tRNA is cyan, and the E-site tRNA is dark green.

Adapted from A. S. Petrov et al., 2015, Proc. Natl. Acad. Sci. U.S.A. 112:15396–15401. Courtesy of Loren Williams.

Additional Information

Groups

College of Sciences

Categories
Life Sciences and Biology
Keywords
College of Sciences, Loren Williams, Origin Of Life, ribosome evolution, School of Chemistry and Biochemistry
Status
  • Created By: A. Maureen Rouhi
  • Workflow Status: Published
  • Created On: Aug 18, 2016 - 12:47pm
  • Last Updated: Oct 7, 2016 - 10:56pm