Substrate-Induced Formation of Ribosomal Decoding Center for Accurate and Rapid Genetic Code Translation

Accurate translation of genetic information is crucial for synthesis of functional proteins in all organisms. We use recent experimental data to discuss how induced fit affects accuracy of initial codon selection on the ribosome by aminoacyl transfer RNA in ternary complex (T-3) with elongation factor Tu (EF-Tu) and guanosine-5'-triphosphate (GTP). We define actual accuracy (A(I)(nc)) of a particular protein synthesis system as its current accuracy and the effective selectivity (d(eI)(nc)) as A(I)(nc) in the limit of zero ribosomal binding affinity for T-3. Intrinsic selectivity (D-I(nc)), defined as the upper thermodynamic limit of d(eI)(nc), is determined by the free energy difference between near-cognate and cognate T-3 in the pre-GTP hydrolysis state on the ribosome. D-I(nc) is much larger than d(eI)(nc), suggesting the possibility of a considerable increase in d(eI)(nc) and A(I)(nc) at negligible kinetic cost. Induced fit increases A(I)(nc) and d(eI)(nc) without affecting D-I(nc), and aminoglycoside antibiotics reduce A(I)(nc) and d(eI)(nc) at unaltered D-I(nc).