The 2C putative helicase of echovirus 30 adopts a hexameric ring-shaped structure

Abstract

The 2C protein, which is an essential ATPase and one of the most conserved proteins across the Picornaviridae family, is an emerging antiviral target for which structural and functional characterization remain elusive. Based on a distant relationship to helicases of small DNA viruses, piconavirus 2C proteins have been predicted to unwind double-stranded RNAs. Here, a terminally extended variant of the 2C protein from echovirus 30 has been studied by means of enzymatic activity assays, transmission electron microscopy, atomic force microscopy and dynamic light scattering. The transmission electron-microscopy technique showed the existence of ring-shaped particles with ∼12 nm external diameter. Image analysis revealed that these particles were hexameric and resembled those formed by superfamily 3 DNA virus helicases.

Screening of a Library of FDA-Approved Drugs Identifies Several Enterovirus Replication Inhibitors That Target Viral Protein 2C

“…The in vitro data for dibucaine binding to protein 2C were consistent with a stoichiometric ratio of protein to compound of ∼0.5, equivalent to two molecules of 2C protein and one molecule of dibucaine. In line with data from homologous proteins, the functional form of enteroviral protein 2C is thought to be an oligomer, most likely a hexamer, and there is experimental evidence to support this proposition ( 25 , 26 ). Differences in the affinities of the compounds for different oligomeric forms could conceivably explain the differences in protein binding observed in this assay.…”

“…We analyzed the binding of dibucaine and pirlindole to protein 2C in vitro using isothermal titration calorimetry (ITC). The production and purification of full-length 2C proteins usually lead to polydisperse preparations, which are not amenable to ITC experiments ( 25 ). By removing the 36 N-terminal amino acids containing the amphipathic helix, we generated a monomeric protein (CV-B3 2C Del36) that can be used for ITC experiments.…”

The complete genome sequence of a single-stranded RNA virus from the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois)

“…Simian virus 40 helicase, which represents the super family 3 helicases, forms a hexameric ring and participates in viral replication (Hickman and Dyda, 2005). Helicase/ATPase of the RNA viruses is also thought to form a hexameric ring (Papageorgiou et al, 2010). The SWISS-MODEL matched the helicase domain of LyLV-1 polyprotein with a structure of the D2 hexamerization domain (PDB: 1nsf) of n-ethylmaleimide sensitive factor (nsf) from Chinese hamster, Cricetulus griseus (Neuwald, 1999;Yu et al, 1998) indicating the presence of a putative hexamerization domain in the helicase of the LyLV-1.…”

Detection and molecular characterization of infectious bronchitis-like viruses in wild bird populations

“…At the 3′ end are genes encoding the four major structural proteinsspike (S), envelope (E), matrix (M), and nucleocapsid (N)with genes 3 and 5 encoding non-structural accessory proteins Hodgson et al, 2006). The genome of CoV includes untranslated regions (Papageorgiou et al, 2010) at the 5′ and 3′ genome termini, which play a role in viral RNA synthesis (Sawicki et al, 2007).…”