title: Identification of CD46 binding sites within the adenovirus serotype 35 fiber knob.
abstract: Species B human adenoviruses (Ads) are often associated with fatal illnesses in immunocompromised individuals. Recently, species B Ads, most of which use the ubiquitously expressed complement regulatory protein CD46 as a primary attachment receptor, have gained interest for use as gene therapy vectors. In this study, we focused on species B Ad serotype 35 (Ad35), whose trimeric fiber knob domain binds to three CD46 molecules with a KD (equilibrium dissociation constant) of 15.5 nM. To study the Ad35 knob-CD46 interaction, we generated an expression library of Ad35 knobs with random mutations and screened it for CD46 binding. We identified four critical residues (Phe242, Arg279, Ser282, and Glu302) which, when mutated, ablated Ad35 knob binding to CD46 without affecting knob trimerization. The functional importance of the identified residues was validated in surface plasmon resonance and competition binding studies. To model the Ad35 knob-CD46 interaction, we resolved the Ad35 knob structure at 2-A resolution by X-ray crystallography and overlaid it onto the existing structure for Ad11-CD46 interaction. According to our model, all identified Ad35 residues are in regions that interact with CD46, whereby one CD46 molecule binds between two knob monomers. This mode of interaction might have potential consequences for CD46 signaling and intracellular trafficking of Ad35. Our findings are also fundamental for better characterization of species B Ads and design of antiviral drugs, as well as for application of species B Ads as in vivo and in vitro gene transfer vectors.
authors: Division of Medical Genetics, University of Washington, Box 357720, Seattle, WA 98195, USA.
authors: Hongjie
authors: H
authors: Wang
authors: Yen-Chywan
authors: YC
authors: Liaw
authors: Daniel
authors: D
authors: Stone
authors: Oleksandr
authors: O
authors: Kalyuzhniy
authors: Imameddin
authors: I
authors: Amiraslanov
authors: Sebastian
authors: S
authors: Tuve
authors: Christophe L M J
authors: CL
authors: Verlinde
authors: Dmitry
authors: D
authors: Shayakhmetov
authors: Thilo
authors: T
authors: Stehle
authors: Steve
authors: S
authors: Roffler
authors: André
authors: A
authors: Lieber
mesh_terms: D000256:Adenoviridae / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D019943:Amino Acid Substitution / Q000235:genetics; D001665:Binding Sites; D036022:Capsid Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D018360:Crystallography, X-Ray; D004252:DNA Mutational Analysis; D006801:Humans; D051916:Membrane Cofactor Protein / Q000378:metabolism*; D008958:Models, Molecular; D020125:Mutation, Missense; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011991:Receptors, Virus / Q000378:metabolism; D020349:Surface Plasmon Resonance
chemical_list: D036022:Capsid Proteins; D051916:Membrane Cofactor Protein; D011991:Receptors, Virus; C018315:hexon capsid protein, Adenovirus