title: A naturally occurring NAR variable domain binds the Kgp protease from Porphyromonas gingivalis.
abstract: The new antigen receptor (NAR) from sharks consists of a single immunoglobulin variable domain attached to five constant domains, and is hypothesised to function as an antibody. Two closely related NARs with affinity for the Kgp (lysine-specific) gingipain protease from Porphyromonas gingivalis were selected by panning an NAR variable domain library. When produced in Escherichia coli, these recombinant NARs were stable, correctly folded, and specifically bound Kgp (K(d)=1.31+/-0.26x10(-7) M). Binding localised to the Kgp adhesin domains, however without inhibiting adhesin activity. These naturally occurring proteins indicate an immune response to pathogenic bacteria and suggest that the NAR is a true antibody-like molecule.
authors.affiliation: CSIRO Health Sciences and Nutrition, 343 Royal Parade, 3052, Parkville, Vic., Australia. stewart.nuttall@hsn.csiro.au
authors.forename: Stewart D
authors.initials: SD
authors.lastname: Nuttall
authors.forename: Usha V
authors.initials: UV
authors.lastname: Krishnan
authors.forename: Larissa
authors.initials: L
authors.lastname: Doughty
authors.forename: Anne
authors.initials: A
authors.lastname: Nathanielsz
authors.forename: Nafisa
authors.initials: N
authors.lastname: Ally
authors.forename: Robert N
authors.initials: RN
authors.lastname: Pike
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Hudson
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Kortt
authors.forename: Robert A
authors.initials: RA
authors.lastname: Irving
mesh_terms: D018829:Adhesins, Bacterial; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D004247:DNA / Q000235:genetics; D018604:Epitope Mapping; D000080867:Gingipain Cysteine Endopeptidases; D006388:Hemagglutinins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D007136:Immunoglobulins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D019151:Peptide Library; D016966:Porphyromonas gingivalis / Q000201:enzymology / Q000235:genetics; D017434:Protein Structure, Tertiary; D011946:Receptors, Antigen / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012754:Sharks / Q000276:immunology
chemical_list: D018829:Adhesins, Bacterial; D000080867:Gingipain Cysteine Endopeptidases; D006388:Hemagglutinins; D007136:Immunoglobulins; D019151:Peptide Library; D011946:Receptors, Antigen; D011994:Recombinant Proteins; C092388:nurse shark antigen receptor; D004247:DNA; D003546:Cysteine Endopeptidases