Constant for GTPase activation step of tRNA selection for cognate tRNA

Range 120-500 sec^-1
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
Primary Source Gromadski KB, Daviter T, Rodnina MV. A uniform response to mismatches in codon-anticodon complexes ensures ribosomal fidelity. Mol Cell. 2006 Feb 321(3):369-77.PubMed ID16455492
Method pre-steady-state kinetic experiments. the EF-Tu active site undergoes a conformational change (k3), as monitored using the environmentally-sensitive fluorescence analog mant-dGTP.
Comments Cognate=tRNA with correct codon. Near cognate=tRNA with single nucleotide mismatch in codon. Initial views of the proofreading model for tRNA selection would have predicted that the GTPase activation step (k3) of the selection pathway proceeds at a constant rate, serving as an “internal clock”. However, research demonstrated that the rate of GTPase activation strongly depends on the properties of the decoding helix (pairing interaction between the codon and the anticodon).
Entered by Uri M
ID 103475