The Crystal Structure of a Coxsackievirus B3-RD Variant and a Refined 9-Angstrom Cryo-Electron Microscopy Reconstruction of the Virus Complexed with Decay-Accelerating Factor (DAF) Provide a New Footprint of DAF on the Virus Surface

Abstract

The coxsackievirus-adenovirus receptor (CAR) and decay-accelerating factor (DAF) have been identified as cellular receptors for coxsackievirus B3 (CVB3). The first described DAF-binding isolate was obtained during passage of the prototype strain, Nancy, on rhabdomyosarcoma (RD) cells, which express DAF but very little CAR. Here, the structure of the resulting variant, CVB3-RD, has been solved by X-ray crystallography to 2.74 Å, and a cryo-electron microscopy reconstruction of CVB3-RD complexed with DAF has been refined to 9.0 Å. This new high-resolution structure permits us to correct an error in our previous view of DAF-virus interactions, providing a new footprint of DAF that bridges two adjacent protomers. The contact sites between the virus and DAF clearly encompass CVB3-RD residues recently shown to be required for binding to DAF; these residues interact with DAF short consensus repeat 2 (SCR2), which is known to be essential for virus binding. Based on the new structure, the mode of the DAF interaction with CVB3 differs significantly from the mode reported previously for DAF binding to echoviruses. Coxsackieviruses are significant human pathogens that cause myocarditis, meningitis, and pancreatitis and have been implicated in the development of juvenile diabetes (58, 60-64). Virulence determinants have been described throughout the genome (19,20,30,51,65), including the P1 region, which encodes the structural proteins (7,10,13,25,48,49,56). The capsid surface presents a topology of structural motifs that largely dictate receptor recognition and usage, directly affecting tropism and pathogenicity.Group B coxsackieviruses (CVBs) belong to the genus Enterovirus of the family Picornaviridae. Picornaviruses are nonenveloped, positive-sense, single-stranded-RNA animal viruses with a capsid comprised of 60 protomers arranged to form an icosahedral shell ϳ300 Å in diameter with Tϭ1 (pseudo-Tϭ3) symmetry (ICTV classification) (8). In mature capsids, each protomer contains four structural proteins, VP-1, -2, -3, and -4. Structural studies have shown that capsids share common features, including a depression around the icosahedral 5-fold symmetry axes (called the "canyon") and a hydrophobic cavity located underneath the floor of the canyon (called the "pocket") (52). Biochemical and structural evidence indicates that the ligand within the pocket is a fatty acid (26, 55). For many picornaviruses, a receptor binds into the canyon and dislodges this "pocket factor," initiating conformational changes that lead to the formation of "A particles" and the subsequent uncoating of the virion (1, 12, 33, 39, 66). The major CVB receptor, the coxsackievirus-adenovirus receptor (CAR), binds within the CVB3 canyon (37) and causes the formation of A particles (16,35).A number of CVB isolates bind a second receptor, decayaccelerating factor (DAF) (CD55), a molecule that also serves as a receptor for many other enteroviruses (2,3,18,23,24,43,45). DAF, which is expressed on virtually all cell surfaces, acts to protect cells from lysis ...

Is a multivalent hand, foot, and mouth disease vaccine feasible?

“…VP1, VP2 and VP3 are displayed on the surface of the virion surface as shown in the EV-A71 and CV-B3 crystal structures. [92][93][94] These subunits expose linear and conformational neutralization epitopes and are responsible for immune responses and host-receptor binding. VP1 contains major neutralization determinants and is used in viral identification and evolutionary analyses.…”

Kinetic and Structural Analysis of Coxsackievirus B3 Receptor Interactions and Formation of the A-Particle

“…These viruses are icosahedral, nonenveloped, and approximately 300 Å in diameter, with a positive-sense single-stranded RNA genome (5). The crystal structures of CVB3-M and CVB3-RD strains are available in the Protein Data Bank (PDB) (PDB identifiers [ID] 1COV and 4GB3) (6,7). The capsid has a Tϭ1 (pseudo Tϭ3) icosahedral architecture, is composed of four viral proteins (VP1 to -4), and has distinct topological features that are important to the function of the virus (Fig.…”

Interspecies Differences in Virus Uptake versus Cardiac Function of the Coxsackievirus and Adenovirus Receptor

“…This interaction is conserved in the family Picornaviridae (16)(17)(18). CVB3s use the coreceptor decay accelerating factor (DAF) for cell attachment (19), which binds adjacent to the CAR interaction sites on the virus surface (20). DAF alone is not sufficient for virus infection (21).…”