title: Probing the equatorial groove of the hookworm protein and vaccine candidate antigen, Na-ASP-2.
abstract: Hookworm activation-associated secreted proteins can be structurally classified into at least three different groups. The hallmark feature of Group 1 activation-associated secreted proteins is a prominent equatorial groove, which is inferred to form a ligand binding site. Furthermore, a conserved tandem histidine motif is located in the centre of the groove and believed to provide or support a yet to be determined catalytic activity. Here, we report three-dimensional crystal structures of Na-ASP-2, an L3-secreted activation-associated secreted protein from the human hookworm Necator americanus, which demonstrate transition metal binding ability of the conserved tandem histidine motif. We further identified moderate phosphohydrolase activity of recombinant Na-ASP-2, which relates to the tandem histidine motif. By panning a random 12-mer peptide phage library, we identified a peptide with high similarity to the human calcium-activated potassium channel SK3, and confirm binding of the synthetic peptide to recombinant Na-ASP-2 by differential scanning fluorimetry. Potential binding modes of the peptide to Na-ASP-2 were studied by molecular dynamics simulations which clearly identify a preferred topology of the Na-ASP-2:SK3 peptide complex.
authors.affiliation: Structural Chemistry Program, Eskitis Institute, Griffith University, Brisbane, Queensland, Australia.
authors.forename: Lyndel
authors.initials: L
authors.lastname: Mason
authors.affiliation: Centre for Biodiscovery and Molecular Development of Therapeutics, Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, Queensland, Australia.
authors.forename: Leon
authors.initials: L
authors.lastname: Tribolet
authors.affiliation: Université Lyon 1, Villeurbanne cedex, and Laboratoire Chimie et Biologie des Membranes et des Nanoobjets, Université Bordeaux, CBMN, UMR 5248, 33600 Pessac, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Simon
authors.affiliation: Structural Chemistry Program, Eskitis Institute, Griffith University, Brisbane, Queensland, Australia.
authors.forename: Natascha
authors.initials: N
authors.lastname: von Gnielinski
authors.affiliation: Structural Chemistry Program, Eskitis Institute, Griffith University, Brisbane, Queensland, Australia.
authors.forename: Lisa
authors.initials: L
authors.lastname: Nienaber
authors.affiliation: Institute for Structural Biology, School of Biological Sciences, The University of Edinburgh, Scotland, UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Taylor
authors.affiliation: Structural Chemistry Program, Eskitis Institute, Griffith University, Brisbane, Queensland, Australia; School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia.
authors.forename: Charlene
authors.initials: C
authors.lastname: Willis
authors.affiliation: School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia; Queensland Institute of Medical Research, Herston, Queensland, Australia.
authors.forename: Malcolm K
authors.initials: MK
authors.lastname: Jones
authors.affiliation: Biology Division, California Institute of Technology, Pasadena, CA, USA.
authors.forename: Paul W
authors.initials: PW
authors.lastname: Sternberg
authors.affiliation: Faculty of Veterinary Science, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Robin B
authors.initials: RB
authors.lastname: Gasser
authors.affiliation: Centre for Biodiscovery and Molecular Development of Therapeutics, Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, Queensland, Australia. Electronic address: alex.loukas@jcu.edu.au.
authors.forename: Alex
authors.initials: A
authors.lastname: Loukas
authors.affiliation: Structural Chemistry Program, Eskitis Institute, Griffith University, Brisbane, Queensland, Australia; Faculty of Veterinary Science, The University of Melbourne, Parkville, Victoria, Australia. Electronic address: a.hofmann@griffith.edu.au.
authors.forename: Andreas
authors.initials: A
authors.lastname: Hofmann
mesh_terms: D000818:Animals; D000947:Antigens, Helminth / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism; D001665:Binding Sites; D018360:Crystallography, X-Ray; D015801:Helminth Proteins / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism; D008958:Models, Molecular; D017221:Necator americanus / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D009332:Necatoriasis / Q000469:parasitology*; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry / Q000378:metabolism; D017434:Protein Structure, Tertiary; D014612:Vaccines / Q000737:chemistry* / Q000276:immunology
chemical_list: D000947:Antigens, Helminth; D015801:Helminth Proteins; D014612:Vaccines; D010744:Phosphoric Monoester Hydrolases
keywords: Activation-associated secreted proteins; Host–parasite interactions; Pathogenesis-related proteins; Protein structure; SCP/TAPS proteins