title: Delineation of interfaces on human alpha-defensins critical for human adenovirus and human papillomavirus inhibition.
abstract: Human α-defensins are potent anti-microbial peptides with the ability to neutralize bacterial and viral targets. Single alanine mutagenesis has been used to identify determinants of anti-bacterial activity and binding to bacterial proteins such as anthrax lethal factor. Similar analyses of α-defensin interactions with non-enveloped viruses are limited. We used a comprehensive set of human α-defensin 5 (HD5) and human neutrophil peptide 1 (HNP1) alanine scan mutants in a combination of binding and neutralization assays with human adenovirus (AdV) and human papillomavirus (HPV). We have identified a core of critical hydrophobic residues that are common determinants for all of the virus-defensin interactions that were analyzed, while specificity in viral recognition is conferred by specific surface-exposed charged residues. The hydrophobic residues serve multiple roles in maintaining the tertiary and quaternary structure of the defensins as well as forming an interface for virus binding. Many of the important solvent-exposed residues of HD5 group together to form a critical surface. However, a single discrete binding face was not identified for HNP1. In lieu of whole AdV, we used a recombinant capsid subunit comprised of penton base and fiber in quantitative binding studies and determined that the anti-viral potency of HD5 was a function of stoichiometry rather than affinity. Our studies support a mechanism in which α-defensins depend on hydrophobic and charge-charge interactions to bind at high copy number to these non-enveloped viruses to neutralize infection and provide insight into properties that guide α-defensin anti-viral activity.
authors.affiliation: Department of Microbiology, University of Washington, Seattle, Washington, United States of America.
authors.forename: Victoria R
authors.initials: VR
authors.lastname: Tenge
authors.affiliation: Department of Microbiology, University of Washington, Seattle, Washington, United States of America.
authors.forename: Anshu P
authors.initials: AP
authors.lastname: Gounder
authors.affiliation: Department of Microbiology, University of Washington, Seattle, Washington, United States of America.
authors.forename: Mayim E
authors.initials: ME
authors.lastname: Wiens
authors.affiliation: Institute of Human Virology and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Wuyuan
authors.initials: W
authors.lastname: Lu
authors.affiliation: Department of Microbiology, University of Washington, Seattle, Washington, United States of America.
authors.forename: Jason G
authors.initials: JG
authors.lastname: Smith
mesh_terms: D000258:Adenovirus Infections, Human / Q000517:prevention & control* / Q000821:virology; D000260:Adenoviruses, Human / Q000187:drug effects*; D000998:Antiviral Agents / Q000737:chemistry / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D016296:Mutagenesis; D027383:Papillomaviridae / Q000187:drug effects*; D030361:Papillomavirus Infections / Q000517:prevention & control* / Q000821:virology; D011487:Protein Conformation; D020349:Surface Plasmon Resonance; D053585:Virus Attachment; D023084:alpha-Defensins / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D000998:Antiviral Agents; C500225:DEFA5 protein, human; D023084:alpha-Defensins