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Journal of Undergraduate Research

Keywords

tmRNA, aminoacyl-tRNA site, A-site, endouclease, ribosome

College

Physical and Mathematical Sciences

Department

Chemistry and Biochemistry

Abstract

Trans-translation can be broken down into 5 steps. , After a ribosome stalls, the mRNA in its aminoacyl-tRNA site (A-site) is cleaved and released, which leaves the A-site empty. The key molecule in ribosomal rescue, transfer-messenger RNA (tmRNA), then forms a complex with Small Protein B (SmpB). This complex is recruited into the empty A-site of the stalled ribosome. tmRNA contains a message in an open reading frame, which encodes a degradation tag that will be added to the protein later. In the next surprising step, the ribosome switches RNA templates from the stalled mRNA to tmRNA, resuming translation on the mRNA portion of tmRNA and synthesizing a degradation tag (amino acid sequence: AANDENYALAA) at the end of the protein. The ribosome reaches a stop signal in the tmRNA open reading frame, the tagged protein is released and degraded by proteases, and the ribosome is rescued.

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