title: Interaction of alphaVbeta3 and alphaVbeta6 integrins with human parechovirus 1.
abstract: Human parechovirus (HPEV) infections are very common in early childhood and can be severe in neonates. It has been shown that integrins are important for cellular infectivity of HPEV1 through experiments using peptide blocking assays and function-blocking antibodies to alpha(V) integrins. The interaction of HPEV1 with alpha(V) integrins is presumably mediated by a C-terminal RGD motif in the capsid protein VP1. We characterized the binding of integrins alpha(V)beta(3) and alpha(V)beta(6) to HPEV1 by biochemical and structural studies. We showed that although HPEV1 bound efficiently to immobilized integrins, alpha(V)beta(6) bound more efficiently than alpha(V)beta(3) to immobilized HPEV1. Moreover, soluble alpha(V)beta(6), but not alpha(V)beta(3), blocked HPEV1 cellular infectivity, indicating that it is a high-affinity receptor for HPEV1. We also showed that HPEV1 binding to integrins in vitro could be partially blocked by RGD peptides. Using electron cryo-microscopy and image reconstruction, we showed that HPEV1 has the typical T=1 (pseudo T=3) organization of a picornavirus. Complexes of HPEV1 and integrins indicated that both integrin footprints reside between the 5-fold and 3-fold symmetry axes. This result does not match the RGD position predicted from the coxsackievirus A9 X-ray structure but is consistent with the predicted location of this motif in the shorter C terminus found in HPEV1. This first structural characterization of a parechovirus indicates that the differences in receptor binding are due to the amino acid differences in the integrins rather than to significantly different viral footprints.
authors.affiliation: Department of Biosciences, Institute of Biotechnology, PO Box 65, Viikinkaari 1, FIN-00014 University of Helsinki, Finland.
authors.forename: Jani
authors.initials: J
authors.lastname: Seitsonen
authors.forename: Petri
authors.initials: P
authors.lastname: Susi
authors.forename: Outi
authors.initials: O
authors.lastname: Heikkilä
authors.forename: Robert S
authors.initials: RS
authors.lastname: Sinkovits
authors.forename: Pasi
authors.initials: P
authors.lastname: Laurinmäki
authors.forename: Timo
authors.initials: T
authors.lastname: Hyypiä
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Butcher
mesh_terms: D000595:Amino Acid Sequence; D000951:Antigens, Neoplasm / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D006801:Humans; D039302:Integrin alphaVbeta3 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016023:Integrins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D030061:Parechovirus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010850:Picornaviridae Infections / Q000378:metabolism* / Q000821:virology; D011485:Protein Binding; D016415:Sequence Alignment; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D000951:Antigens, Neoplasm; D039302:Integrin alphaVbeta3; D016023:Integrins; D014764:Viral Proteins; C073878:integrin alphavbeta6