Poster abstracts

Poster number 65 submitted by Sean McClory

Error-prone mutations in 16S rRNA provide insight into the decoding mechanism

Sean P. McClory (OSBP, OSU Center for RNA Biology, Dept. of Microbiology), Aishwarya Devaraj (OSBP, OSU Center for RNA Biology, Dept. of Microbiology), Kurt Fredrick (OSBP, OSU Center for RNA Biology, Dept. of Microbiology)

Abstract:
During translation, the ribosome contributes to the accuracy of aminoacyl(aa)-tRNA selection during two phases of decoding. During the first phase, initial selection, aa-tRNAs are delivered to the ribosome by elongation factor (EF) Tu. EF-Tu must hydrolyze GTP in order for subsequent steps of decoding to proceed, so the ribosome stimulates GTP hydrolysis for EF-Tu complexes carrying a cognate aa-tRNA, allowing those tRNAs to be preferentially incorporated. In the second decoding phase, proofreading, cognate aa-tRNAs are released from EF-Tu and rapidly accommodated into the 50S A site to undergo peptidyl transfer whereas near-cognate aa-tRNAs are almost always rejected.
Recently, we have identified a number of mutations in the 16S rRNA that significantly reduce the accuracy of aa-tRNA selection. Most of the mutations are located at the interface of the ribosomal shoulder domain with other regions of the ribosme. These mutations stimulate GTP hydrolysis by cognate and near-cognate aa-tRNA, reducing the accuracy of initial selection. Additionally, our data show that many of these mutations significantly affect the accuracy of the proofreading phase. We will present evidence of how these mutations influence proofreading by affecting rates of individual steps of this mechanism. These data implicate specific areas of the ribosome in decoding and provide insight into the molecular mechanisms of antibiotics that inhibit the accuracy of translation.

Keywords: Translation, Ribosome, Decoding