Contribution of selectivity of proofreading stage of tRNA selection for near cognate tRNA

Value 15 Fold
Organism Bacteria Escherichia coli
Reference Hani S. Zaher and Rachel Green, Fidelity at the Molecular Level: Lessons from Protein Synthesis. Cell Volume 136, Issue 4, 20 February 2009, Pages 746-762PubMed ID19239893
Method The data gathered from multiple fluorescent reporters (proflavin- and wybutine- labeled tRNA, mant-dGTP) and chemical assays (GTP hydrolysis and peptidyl transfer), together with global fitting approaches, have allowed for reasonable estimates of the rate constants for nearly all of the identified steps in the tRNA selection pathway. These rates for both cognate and near-cognate ternary complexes can be used to estimate the contribution of each phase of the process (initial selection and proofreading) to the overall accuracy of selection. They can also be used to evaluate whether the calculated predictions match in vivo measurements. Selectivity during initial selection is dictated by the relative kcat/Km values.
Comments Near cognate tRNA=carrying one mismatched nucleotide in codon. In the proofreading stage the tRNA either moves into the A-site (accommodation, k5) of the large ribosome subunit and participates in peptidyl transfer (kpep), or dissociates from the ribosome (rejection, k7).
Entered by Uri M
ID 103480