Graduate School of Frontier Biosciences, Osaka University


"Rethinking the genetic code as a triplet-of-triplets"
Prof. Kelly T. Hughes (Department of Biology, The University of Utah)


Mar 14, 2018 (Thu), 13:30-14:30


2F Seminar room, BioSystems Building


Prof. Kelly T. Hughes (Department of Biology, The University of Utah)


Rethinking the genetic code as a triplet-of-triplets


DNA is transcribed into mRNA by RNA polymerase, which is translated into protein by ribosomes. The genetic code for the amino acid sequences of proteins is composed of 64 triplet codons that specify the twenty amino acids and sites of translation termination (stop codons). The interaction between a specific codon in the mRNA being translated and the three bases that define the anticodon of the cognate aminoacyl-tRNA determines the decoding process. The code is redundant in that many amino acids are specified by two or more triplet sequences. In addition, codons specifying a particular amino acid are recognized by single or multiple tRNAs. Most tRNA species can recognize multiple codons that differ in the third or wobble position. I will present evidence that the ability for a given triplet sequence in the mRNA to be translated is highly dependent on the two adjacent codons. In essence, the genetic code can be considered not a triplet code, but a triplet of triplets. Furthermore, I will show that adjacent codons can dramatically affect the speed that the ribosome can reads through a given codon. Thus, gene expression can be dramatically altered through synonymous codon usage.


Keiichi Namba