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CryoEM reconstruction of Cowpea Mosaic Virus (CPMV) bound to an Affimer reagent
Structural highlights
Function[POL2_CPMVS] Movement protein: transports viral genome to neighboring plant cells directly through plasmosdesmata, without any budding. The movement protein allows efficient cell to cell propagation, by bypassing the host cell wall barrier. Acts by forming a tubular structure at the host plasmodesmata, enlarging it enough to allow free passage of virion capsids. Binds to GTP and to single-stranded RNA and single-stranded DNA in a non-sequence-specific manner.[1] [2] [3] [4] The cleavable C-terminus of small coat protein seems to be involved in the packaging of the virion RNAs. Also seems to act as suppressor of post-transcriptional gene silencing (PTGS), a mechanism of plant viral defense that limits the accumulation of viral RNAs.[5] [6] [7] [8] Publication Abstract from PubMedPlant viruses can cause devastating losses to agriculture and are therefore a major threat to food security. The rapid identification of virally-infected crops allowing containment is essential to limit such threats, but plant viral diseases can be extremely challenging to diagnose. An ideal method for plant virus diagnosis would be a device which can be implemented easily in the field. Such devices require a binding reagent that is specific for the virus of interest. We chose to investigate the use of Affimer reagents, artificial binding proteins and a model plant virus Cowpea Mosaic virus (CPMV) empty virus like particles (eVLPs). CPMV-eVLP mimic the morphology of wild-type (WT) CPMV but lack any infectious genomic material and so do not have biocontainment issues. We have produced and purified an Affimer reagent selected for its ability to bind to CPMV-eVLP and have shown that the selected Affimer also specifically binds to WT CPMV. We have produced a 3.4 A structure of WT CPMV bound to the Affimer using cryo-electron microscopy. Finally, we have shown that this Affimer is capable of reliably detecting the virus in crude extracts of CPMV-infected leaves and can therefore form the basis for the future development of diagnostic tests. Affimer reagents as tools in diagnosing plant virus diseases.,Hesketh EL, Tiede C, Adamson H, Adams TL, Byrne MJ, Meshcheriakova Y, Kruse I, McPherson MJ, Lomonossoff GP, Tomlinson DC, Ranson NA Sci Rep. 2019 May 17;9(1):7524. doi: 10.1038/s41598-019-43945-6. PMID:31101847[9] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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