8AX4

Crystal structure of FMV N in its RNA-free form

Summary for 8AX4

• Entry DOI: 10.2210/pdb8ax4/pdb
• Descriptor: Nucleocapsid protein, 2-AMINO-2-HYDROXYMETHYL-PROPANE-1,3-DIOL (3 entities in total)
• Functional Keywords: nucleoprotein, genome packaging, virus, rna, fig mosaic virus, viral protein
• Biological source: Emaravirus fici
• Total number of polymer chains: 4
• Total formula weight: 140795.28

Authors

Izhaki-Tavor, L.,Yechezkel, I.,Dessau, M. (deposition date: 2022-08-30, release date: 2023-04-05, Last modification date: 2024-11-13)

Primary citation

Izhaki-Tavor, L.S.,Yechezkel, I.G.,Alter, J.,Dessau, M.
RNA Encapsulation Mode and Evolutionary Insights from the Crystal Structure of Emaravirus Nucleoprotein.
Microbiol Spectr, 11:e0501822-e0501822, 2023

PubMed Abstract: Enveloped RNA viruses are rare among plant viruses. is a newly founded family of plant viruses within the order that inflicts diverse crop losses worldwide. The fig mosaic virus (FMV), the representative member of the family, was shown to be a causative agent for the fig mosaic disease. Like all bunyaviruses, FMV has a segmented, negative-sense, single-stranded RNA (ssRNA) genome that is encapsulated by the viral nucleoprotein (N). Here, we present high-resolution crystal structures of FMV N in its RNA-free and RNA-bound forms, revealing a "paper fortune teller" structural transition between the two states. The tightly packed tetramer of FNV N is similar to the structures of other N proteins of different members of the order. In its RNA-bound form, the tetramer reorganizes to adopt a more open state that allows the accommodation of the RNA. Despite the low sequence similarity to N proteins of animal-infecting bunyaviruses, there is a striking structural resemblance between FMV N and nucleoproteins from members of the , an animal-infecting family of viruses. This structural homology implies that enveloped plant viruses and animal-infecting viruses might have a common ancestor from which they diverged. Most insect-born viruses circulate within the kingdom, whereas plant-infecting RNA viruses are cross-kingdom pathogens. Many plant-infecting viruses cause devastating crop damage that leads to food security endangerment. The evolutionary crossroads of interkingdom circulation and infection are poorly understood. Thus, we took the structural approach to understand the similarities and differences between interkingdom-infecting viruses and viruses that circulate within one kingdom of life. Using our structures of FMV N in its free form and in complex with a single-stranded RNA (ssRNA), we dissected the mechanism by which FMV N binds to the RNA and revealed the conformational changes associated with the binding. The resemblance of our structure to N proteins from members of the family and their recently published ribonucleoprotein (RNP) pseudoatomic resolution assembly model suggests that the FMV genome is similarly encapsulated. Thus, our finding unveils yet another bridge by which plant- and animal-infecting viruses are interconnected.

PubMed: 37039649
DOI: 10.1128/spectrum.05018-22

Experimental method

X-RAY DIFFRACTION (2.28 Å)