Nonstructural protein sigma NS (protein), Avian orthoreovirus
機能・相同性
Reovirus non-structural protein sigma NS / Sigma NS protein / single-stranded RNA binding / RNA-dependent RNA polymerase activity / Nonstructural protein sigma NS
機能・相同性情報
生物種
Avian orthoreovirus (ウイルス)
引用
ジャーナル: Nucleic Acids Res / 年: 2018 タイトル: Stability of local secondary structure determines selectivity of viral RNA chaperones. 著者: Jack P K Bravo / Alexander Borodavka / Anders Barth / Antonio N Calabrese / Peter Mojzes / Joseph J B Cockburn / Don C Lamb / Roman Tuma / 要旨: To maintain genome integrity, segmented double-stranded RNA viruses of the Reoviridae family must accurately select and package a complete set of up to a dozen distinct genomic RNAs. It is thought ...To maintain genome integrity, segmented double-stranded RNA viruses of the Reoviridae family must accurately select and package a complete set of up to a dozen distinct genomic RNAs. It is thought that the high fidelity segmented genome assembly involves multiple sequence-specific RNA-RNA interactions between single-stranded RNA segment precursors. These are mediated by virus-encoded non-structural proteins with RNA chaperone-like activities, such as rotavirus (RV) NSP2 and avian reovirus σNS. Here, we compared the abilities of NSP2 and σNS to mediate sequence-specific interactions between RV genomic segment precursors. Despite their similar activities, NSP2 successfully promotes inter-segment association, while σNS fails to do so. To understand the mechanisms underlying such selectivity in promoting inter-molecular duplex formation, we compared RNA-binding and helix-unwinding activities of both proteins. We demonstrate that octameric NSP2 binds structured RNAs with high affinity, resulting in efficient intramolecular RNA helix disruption. Hexameric σNS oligomerizes into an octamer that binds two RNAs, yet it exhibits only limited RNA-unwinding activity compared to NSP2. Thus, the formation of intersegment RNA-RNA interactions is governed by both helix-unwinding capacity of the chaperones and stability of RNA structure. We propose that this protein-mediated RNA selection mechanism may underpin the high fidelity assembly of multi-segmented RNA genomes in Reoviridae.