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Figure 4 | Biology Direct

Figure 4

From: The evolution and functional repertoire of translation proteins following the origin of life

Figure 4

A model of protein enhancement in the primitive translation system. The protein functions illustrated here are imparted by the earliest translation protein fold architectures and are summarized in Figure 3. A) The ancestor of the class I aminoacyl tRNA synthetase (ARS) catalytic domain charges tRNAs with amino acids (lowest ancestry value = 5.7%). B) An ancestor of a noncatalytic ARS domain binds tRNA anticodon and interacts with protein "A" during aminoacylation of the tRNA (lowest ancestry value = 1.3%). C) Ancestors of RNA modification enzymes add small organic molecules to tRNA and rRNA to adjust mutual binding affinity (lowest ancestry value = 1.9%). D) Ancestors of regulatory factor domains bind mRNA and tRNA to stabilize their interaction during peptide chain initiation and elongation (lowest ancestry value = 1.3%). E) Ancestors of the regulatory factor GTPases drive peptide elongation forward and sensitize the ribosome to codon-anticodon mismatches (lowest ancestry value = 0.0%). F) Ancestors of ribosomal proteins are able to bind rRNA and one another to stabilize the primitive ribosome complex (lowest ancestry value = 0.6%). These functions were all present before 6% ancestry, indicating that a robust translation system existed early on in the RNA-protein world.

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