Structural and functional glimpse into viral siRNA silencing suppression by an Emaravirus
2Department of Plant Pathology, University of Nebraska-Lincoln, USA
Food security is a growing global concern caused by both climate change and plant pathogens. The High Plains Wheat Mosaic Virus (HPWMoV) is a member of the newly discovered Emaravirus genus (Family: Fimoviridae), transmitted by the wheat curl mite (Aceria tosichella). It is the causative agent of the High-Plains disease in wheat, maize, and other cereal grains, resulting in a substantial economic burden.
RNA silencing is an important defense mechanism in plants to fight viral infections through transcriptional and post-transcriptional gene silencing. To evade RNA silencing response by the host, viruses have developed suppressor proteins that inhibit this defense pathway. These viral RNA silencing suppressors vary in their structures, assembly, and mechanisms of action.
Two HPWMoV proteins, P7 and P8, were recently found to suppress RNA silencing in wheat and other plant model systems. Neither P7 nor P8 show significant sequence homology to any other protein, particularly to other RNA silencing suppressors, leaving a critical gap in knowledge about their structures and mechanism(s) of action and the possible ways plants can fight it.
Here, we present structural, biochemical, and functional investigations of HPWMoV P8 that will shed light on novel mechanisms for RNA silencing suppression by viruses.