Polerovirus N-terminal readthrough domain structures reveal molecular strategies for mitigating virus transmission by aphids.

Schiltz, Carl J; Wilson, Jennifer R; Hosford, Christopher J; Adams, Myfanwy C; Preising, Stephanie E; DeBlasio, Stacy L; MacLeod, Hannah J; Van Eck, Joyce et al. · Nat Commun · 2022

basic_science · Level V

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Abstract

Poleroviruses, enamoviruses, and luteoviruses are icosahedral, positive sense RNA viruses that cause economically important diseases in food and fiber crops. They are transmitted by phloem-feeding aphids in a circulative manner that involves the movement across and within insect tissues. The N-terminal portion of the viral readthrough domain (<sup>N</sup>RTD) has been implicated as a key determinant of aphid transmission in each of these genera. Here, we report crystal structures of the <sup>N</sup>RTDs from the poleroviruses turnip yellow virus (TuYV) and potato leafroll virus (PLRV) at 1.53-Å and 2.22-Å resolution, respectively. These adopt a two-domain arrangement with a unique interdigitated topology and form highly conserved dimers that are stabilized by a C-terminal peptide that is critical for proper folding. We demonstrate that the PLRV <sup>N</sup>RTD can act as an inhibitor of virus transmission and identify <sup>N</sup>RTD mutant variants that are lethal to aphids. Sequence conservation argues that enamovirus and luteovirus <sup>N</sup>RTDs will follow the same structural blueprint, which affords a biological approach to block the spread of these agricultural pathogens in a generalizable manner.

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