title: The solution structure and dynamics of human neutrophil gelatinase-associated lipocalin.
abstract: Human neutrophil gelatinase-associated lipocalin (HNGAL) is a member of the lipocalin family of extracellular proteins that function as transporters of small, hydrophobic molecules. HNGAL, a component of human blood granulocytes, binds bacterially derived formyl peptides that act as chemotactic agents and induce leukocyte granule discharge. HNGAL also forms a complex with the proenzyme form of matrix metalloproteinase-9 (pro-MMP-9, or progelatinase B) via an intermolecular disulphide bridge. This association allows the subsequent formation of ternary and quaternary metalloproteinase/inhibitor complexes that vary greatly in their metalloproteinase activities. The structure and dynamics of apo-HNGAL have been determined by NMR spectroscopy. Simulated annealing calculations yielded a set of 20 convergent structures with an average backbone RMSD from mean coordinate positions of 0. 79(+/-0.13) A over secondary structure elements. The overall rotational correlation time (13.3 ns) derived from15N relaxation data is consistent with a monomeric protein of the size of HNGAL (179 residues) under the experimental conditions (1.4 mM protein, pH 6.0, 24.5 degrees C). The structure features an eight-stranded antiparallel beta-barrel, typical of the lipocalin family. One end of the barrel is open, providing access to the binding site within the barrel cavity, while the other is closed by a short 310-helix. The free cysteine residue required for association with pro-MMP-9 lies in an inter-strand loop at the closed end of the barrel. The structure provides a detailed model of the ligand-binding site and has led to the proposal of a site for pro-MMP-9 association. Dynamic data correlate well with structural features, which has allowed us to investigate a mechanism by which a cell-surface receptor might distinguish between apo and holo-HNGAL through conformational changes at the open end of the barrel.
authors.affiliation: Institut für Organische Chemie und Biochemie, Technische Universität München, Lichtenbergstrasse 4, Garching, 85747, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Coles
authors.forename: T
authors.initials: T
authors.lastname: Diercks
authors.forename: B
authors.initials: B
authors.lastname: Muehlenweg
authors.forename: S
authors.initials: S
authors.lastname: Bartsch
authors.forename: V
authors.initials: V
authors.lastname: Zölzer
authors.forename: H
authors.initials: H
authors.lastname: Tschesche
authors.forename: H
authors.initials: H
authors.lastname: Kessler
mesh_terms: D000209:Acute-Phase Proteins; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry*; D003196:Computer Graphics; D017124:Conserved Sequence; D003545:Cysteine; D006801:Humans; D000071068:Lipocalin-2; D054834:Lipocalins; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009504:Neutrophils / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D015513:Oncogene Proteins; D017433:Protein Structure, Secondary; D011518:Proto-Oncogene Proteins; D051381:Rats; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012996:Solutions
chemical_list: D000209:Acute-Phase Proteins; D002352:Carrier Proteins; C489506:LCN2 protein, human; D000071068:Lipocalin-2; D054834:Lipocalins; D015513:Oncogene Proteins; D011518:Proto-Oncogene Proteins; D012996:Solutions; D003545:Cysteine