Resurrection of a Viral Internal Ribosome Entry Site from a 700 Year Old Ancient Northwest Territories Cripavirus ...

• Main Authors: Wang, Xinying, Vlok, Marli, Flibotte, Stephane, Jan, Eric
• Format: Text
• Language: English
• Published: Multidisciplinary Digital Publishing Institute 2021
• Subjects: Northwest Territories; Subarctic
• Online Access: https://dx.doi.org/10.14288/1.0396413; https://doi.library.ubc.ca/10.14288/1.0396413

The dicistrovirus intergenic region internal ribosome entry site (IGR IRES) uses an unprecedented, streamlined mechanism whereby the IRES adopts a triple-pseudoknot (PK) structure to directly bind to the conserved core of the ribosome and drive translation from a non-AUG codon. The origin of this IRES mechanism is not known. Previously, a partial fragment of a divergent dicistrovirus RNA genome, named ancient Northwest territories cripavirus (aNCV), was extracted from 700-year-old caribou feces trapped in a subarctic ice patch. The aNCV IGR sequence adopts a secondary structure similar to contemporary IGR IRES structures, however, there are subtle differences including 105 nucleotides upstream of the IRES of unknown function. Using filter binding assays, we showed that the aNCV IRES could bind to purified ribosomes, and toeprinting analysis pinpointed the start site at a GCU alanine codon adjacent to PKI. Using a bicistronic reporter RNA, the aNCV IGR can direct translation in vitro in a PKI-dependent ...