1:00pm - 2:00pm
Room 417 Mathematics
New York, NY 10027
Class I release factors recognize specific, “stop” codons in an mRNA message, and then catalyze the release of a newly synthesized protein from the ribosome. However, it is unclear how release factors can so specifically and efficiently recognize stop codons without making mistakes at “near-stop” codons that might differ from stop codons by as little as one nucleotide. Using single-molecule fluorescence resonance energy transfer (smFRET), we have investigated the kinetics with which bacterial release factor 1 (RF1) binds to bacterial ribosomal release complexes that carry different stop and near-stop codons in the A-site. The results of these experiments, as well as analogous experiments performed using RF1 mutants or antibiotic inhibitors of RF1 function, reveal that RF1 binding affinity and codon discrimination occurs via a multistep process. Taken together with complementary molecular dynamics simulations of wildtype RF1 and RF1 mutants, our data demonstrate how the conformational dynamics of a conserved “switch” loop modulate RF1 binding affinity and codon discrimination — enabling us to elucidate some of the molecular details through which class I release factors ensure the integrity and fidelity of translation.
Wednesday, February 24, 2016 at 1:00pm
Room 417 Math