title: Tyrosine cross-linking reveals interfacial dynamics in adeno-associated viral capsids during infection.
abstract: Viral capsid dynamics are often observed during infectious events such as cell surface attachment, entry and genome release. Structural analysis of adeno-associated virus (AAV), a helper-dependent parvovirus, revealed a cluster of surface-exposed tyrosine residues at the icosahedral two-fold symmetry axis. We exploited the latter observation to carry out selective oxidation of Tyr residues, which yielded cross-linked viral protein (VP) subunit dimers, effectively "stitching" together the AAV capsid two-fold interface. Characterization of different Tyr-to-Phe mutants confirmed that the formation of cross-linked VP dimers is mediated by dityrosine adducts and requires the Tyr704 residue, which crosses over from one neighboring VP subunit to the other. When compared to unmodified capsids, Tyr-cross-linked AAV displayed decreased transduction efficiency in cell culture. Surprisingly, further biochemical and quantitative microscopy studies revealed that restraining the two-fold interface hinders externalization of buried VP N-termini, which contain a phospholipase A2 domain and nuclear localization sequences critical for infection. These adverse effects caused by tyrosine oxidation support the notion that interfacial dynamics at the AAV capsid two-fold symmetry axis play a role in externalization of VP N-termini during infection.
authors.affiliation: Gene Therapy Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
authors.forename: Eric D
authors.initials: ED
authors.lastname: Horowitz
authors.forename: M G
authors.initials: MG
authors.lastname: Finn
authors.forename: Aravind
authors.initials: A
authors.lastname: Asokan
mesh_terms: D002213:Capsid / Q000737:chemistry / Q000378:metabolism*; D036022:Capsid Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000229:Dependovirus / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D057809:HEK293 Cells; D006367:HeLa Cells; D054884:Host-Pathogen Interactions; D006801:Humans; D008958:Models, Molecular; D009154:Mutation; D010084:Oxidation-Reduction; D010322:Parvoviridae Infections / Q000378:metabolism / Q000821:virology*; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D014443:Tyrosine / Q000235:genetics / Q000378:metabolism*
chemical_list: D036022:Capsid Proteins; D014443:Tyrosine