Significance of the Translation Initiation Machinery Recruiting Structures in the Blackcurrant Reversion Virus RNA 1

Abstract

Unlike most eukaryotic translation which is initiated by the 5′‐m7GpppN cap (5′cap), the two genomic RNAs (RNA 1 and 2) from the Blackcurrant Reversion virus (BRV) do not have a 5′ cap but rather has special region in 3′ untranslated region (UTR) called a cap‐independent translation enhancer (CITE). CITE RNA structures bind translation initiation machinery and delivers that machinery to the 5′ UTR, typically via an RNA kissing‐loop interaction. Our research focuses on the specific RNA structures called translation initiation machinery recruiting structures (TIMRS) in the BRV RNA 1 3′ CITE and 5′ UTR, and their significance in facilitating translation by delivering translation machinery to the 5′ end of the RNA. Using site‐directed mutagenesis to alter the TIMRS and a luciferase reporter to measure protein production of the mutants, we are analyzing the relationship between structure and function. Thus far we have found altering the TIMRS in the 3′ CITE structure does show a difference in protein production compared to the wild type, which indicates the structures' significance and their contribution in translation efficiency. We believe the TIMRS is responsible for recruiting translation machinery or possibly the ability to “kiss” to 5′ UTR stem loop. This study can aid in understanding not only plant viruses but other animal or human RNA viruses that utilize 3′ or 5′ structures to regulate cap‐independent translation.