title: Structural studies of Helix aspersa agglutinin complexed with GalNAc: A lectin that serves as a diagnostic tool.
abstract: Lectins belong to a differentiated group of proteins known to possess sugar-binding properties. Due to this fact, they are interesting research targets in medical diagnostics. Helix aspersa agglutinin (HAA) is a lectin that recognizes the epitopes containing α-d-N-acetylgalactosamine (GalNAc), which is present at the surface of metastatic cancer cells. Although several reports have already described the use of HAA as a diagnostic tool, this protein was not characterized on the molecular level. Here, we present for the first time the structural information about lectin isolated from mucus of Helix aspersa (garden snail). The amino acid sequence of this agglutinin was determined by Edman degradation and tertiary as well as quaternary structure by X-ray crystallography. The high resolution crystal structure (1.38Å) and MALDI-TOF mass spectrometry analysis provide the detailed information about a large part of the HAA natural glycan chain. The topology of the GalNAc binding cleft and interaction with lectin are very well defined in the structure and fully confirmed by STD HSQC NMR spectroscopy. Together, this provides structural clues regarding HAA specificity and opens possibilities to rational modifications of this important diagnostic tool.
authors.affiliation: Institute of Technical Biochemistry, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Stefanowskiego 4/10, Lodz 90-924, Poland.
authors.forename: Agnieszka J
authors.initials: AJ
authors.lastname: Pietrzyk
authors.affiliation: Institute of Technical Biochemistry, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Stefanowskiego 4/10, Lodz 90-924, Poland. Electronic address: anna.bujacz@p.lodz.pl.
authors.forename: Anna
authors.initials: A
authors.lastname: Bujacz
authors.affiliation: Department of Analytical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7A, 30-387 Krakow, Poland; Malopolska Centre of Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Krakow, Poland.
authors.forename: Paweł
authors.initials: P
authors.lastname: Mak
authors.affiliation: University of Louisville School of Dentistry, Department of Oral Immunology and Infectious Diseases, 501 South Preston Street, Louisville, KY 40202, USA.
authors.forename: Barbara
authors.initials: B
authors.lastname: Potempa
authors.affiliation: Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Rudolfa Weigla 12, Wrocław 53-114, Poland.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Niedziela
mesh_terms: D000373:Agglutinins / Q000737:chemistry*; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002851:Chromatography, High Pressure Liquid; D056148:Chromatography, Reverse-Phase; D018604:Epitope Mapping; D005688:Galactosamine / Q000737:chemistry*; D006031:Glycosylation; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000378:metabolism; D012908:Snails / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D055672:Static Electricity; D014961:X-Ray Diffraction; D015032:Zinc / Q000378:metabolism
chemical_list: D000373:Agglutinins; D020033:Protein Isoforms; D005688:Galactosamine; D015032:Zinc
keywords: Helix aspersa agglutinin; N-glycosylated lectin; α-d-N-acetylgalactosamine (GalNAc)