title: Crystal structure of raptor adenovirus 1 fibre head and role of the beta-hairpin in siadenovirus fibre head domains.
abstract: Most adenoviruses recognize their host cells via an interaction of their fibre head domains with a primary receptor. The structural framework of adenovirus fibre heads is conserved between the different adenovirus genera for which crystal structures have been determined (Mastadenovirus, Aviadenovirus, Atadenovirus and Siadenovirus), but genus-specific differences have also been observed. The only known siadenovirus fibre head structure, that of turkey adenovirus 3 (TAdV-3), revealed a twisted beta-sandwich resembling the reovirus fibre head architecture more than that of other adenovirus fibre heads, plus a unique beta-hairpin embracing a neighbouring monomer. The TAdV-3 fibre head was shown to bind sialyllactose.
  
  
  
  Raptor adenovirus 1 (RAdV-1) fibre head was expressed, crystallized and its structure was solved and refined at 1.5 Å resolution. The structure could be solved by molecular replacement using the TAdV-3 fibre head structure as a search model, despite them sharing a sequence identity of only 19 %. Versions of both the RAdV-1 and TAdV-3 fibre heads with their beta-hairpin arm deleted were prepared and their stabilities were compared with the non-mutated proteins by a thermal unfolding assay.
  
  
  
  The structure of the RAdV-1 fibre head contains the same twisted ABCJ-GHID beta-sandwich and beta-hairpin arm as the TAdV-3 fibre head. However, while the predicted electro-potential surface charge of the TAdV-3 fibre head is mainly positive, the RAdV-1 fibre head shows positively and negatively charged patches and does not appear to bind sialyllactose. Deletion of the beta-hairpin arm does not affect the structure of the raptor adenovirus 1 fibre head and only affects the stability of the RAdV-1 and TAdV-3 fibre heads slightly.
  
  
  
  The high-resolution structure of RAdV-1 fibre head is the second known structure of a siadenovirus fibre head domain. The structure shows that the siadenovirus fibre head structure is conserved, but differences in the predicted surface charge suggest that RAdV-1 uses a different natural receptor for cell attachment than TAdV-3. Deletion of the beta-hairpin arm shows little impact on the structure and stability of the siadenovirus fibre heads.
authors.affiliation: Departamento de Estructura de Macromoléculas, Centro Nacional de Biotecnología (CNB-CSIC), Calle Darwin 3, E-28049, Madrid, Spain.|Genetic Engineering Laboratory, Institute of Biotechnology (IBT-VAST), 18 Hoang Quoc Viet, Cau Giay, Hanoi, Vietnam.
authors.forename: Thanh H
authors.initials: TH
authors.lastname: Nguyen
authors.affiliation: Institute for Veterinary Medical Research, Centre for Agricultural Research, Hungarian Academy of Sciences, Budapest, Hungary.
authors.forename: Mónika Z
authors.initials: MZ
authors.lastname: Ballmann
authors.affiliation: Genetic Engineering Laboratory, Institute of Biotechnology (IBT-VAST), 18 Hoang Quoc Viet, Cau Giay, Hanoi, Vietnam.
authors.forename: Huyen T
authors.initials: HT
authors.lastname: Do
authors.affiliation: Genetic Engineering Laboratory, Institute of Biotechnology (IBT-VAST), 18 Hoang Quoc Viet, Cau Giay, Hanoi, Vietnam.
authors.forename: Hai N
authors.initials: HN
authors.lastname: Truong
authors.affiliation: Institute for Veterinary Medical Research, Centre for Agricultural Research, Hungarian Academy of Sciences, Budapest, Hungary.
authors.forename: Mária
authors.initials: M
authors.lastname: Benkő
authors.affiliation: Institute for Veterinary Medical Research, Centre for Agricultural Research, Hungarian Academy of Sciences, Budapest, Hungary.
authors.forename: Balázs
authors.initials: B
authors.lastname: Harrach
authors.affiliation: Departamento de Estructura de Macromoléculas, Centro Nacional de Biotecnología (CNB-CSIC), Calle Darwin 3, E-28049, Madrid, Spain. mjvanraaij@cnb.csic.es.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: van Raaij
mesh_terms: D000256:Adenoviridae / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D000257:Adenoviridae Infections / Q000662:veterinary* / Q000821:virology*; D000818:Animals; D018360:Crystallography, X-Ray; D006801:Humans; D055029:Inverted Repeat Sequences; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D010802:Phylogeny; D000072417:Protein Domains; D020304:Raptors / Q000821:virology; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D014764:Viral Proteins
keywords: Atomic structure; Beta-hairpin; Deletion mutagenesis; Protein stability; Siadenovirus; X-ray crystallography