Probing the Molecular Basis of Allergy

Rouvinen, Juha; Rautiainen, J. Mikko; Virtanen, Tuomas; Zeiler, T.; Kauppinen, Juha; Taivainen, Antti; Mäntyjärvi, Rauno

doi:10.1074/jbc.274.4.2337

Cited by 74 publications

(24 citation statements)

References 31 publications

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“…Also, loops 2 and 3 are shifted toward the central axis of the ␤-barrel in Bda compared with Tlc. As result, the ligand pocket is essentially obstructed in this allergen, and in fact no endogenous ligands, except of two water molecules, were found inside its cavity (45).…”

Section: Discussionmentioning

confidence: 99%

“…2A). Loop 1, which is largely disordered in Tlc but well defined in the Bda crystal structure (45), runs almost across the opening of the calyx, thereby controlling accessibility of the ligand-binding site. The spatial orientation of the segments flanking this loop, which could be built with confidence in the Tlc crystal structure, together with the comparable loop lengths in both lipocalins (with two residues less in Tlc than in Bda; cf.…”

Section: Figmentioning

confidence: 99%

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The 1.8-Å Crystal Structure of Human Tear Lipocalin Reveals an Extended Branched Cavity with Capacity for Multiple Ligands

Breustedt

Korndörfer

Redl

et al. 2005

Journal of Biological Chemistry

106

149

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In contrast with earlier assumptions, which classified human tear lipocalin (Tlc) as an outlier member of the lipocalin protein family, the 1.8-Å resolution crystal structure of the recombinant apoprotein confirms the typical eight-stranded antiparallel ␤-barrel architecture with an ␣-helix attached to it. The fold of Tlc most closely resembles the bovine dander allergen Bos d 2, a well characterized prototypic lipocalin, but also reveals similarity with ␤-lactoglobulin. However, compared with other lipocalin structures Tlc exhibits an extremely wide ligand pocket, whose entrance is formed by four partially disordered loops. The cavity deeply extends into the ␤-barrel structure, where it ends in two distinct lobes. This unusual structural feature explains the known promiscuity of Tlc for various ligands, with chemical structures ranging from lipids and retinoids to the macrocyclic antibiotic rifampin and even to microbial siderophores. Notably, earlier findings of biological activity as a thiol protease inhibitor have no correspondence in the three-dimensional structure of Tlc, rather it appears that its proteolytic fragments could be responsible for this phenomenon. Hence, the present structural analysis sheds new light on the ligand binding activity of this functionally obscure but abundant human lipocalin.

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Section: Discussionmentioning

confidence: 99%

Section: Figmentioning

confidence: 99%

The 1.8-Å Crystal Structure of Human Tear Lipocalin Reveals an Extended Branched Cavity with Capacity for Multiple Ligands

Breustedt

Korndörfer

Redl

et al. 2005

Journal of Biological Chemistry

106

149

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“…Structural knowledge of allergens may therefore have considerable impact on the generation of tools for the immunotherapy of allergic diseases, by providing insight into the mechanisms of immune recognition (14,19) and the physiological role (36) of allergens.…”

Section: Discussionmentioning

confidence: 99%

“…Although the three-dimensional structures of some allergenic lipocalins are known (mMUP (9), rat urinary ␣2-globulin (10), bovine ␤-lactoglobulin (17,18), and Bos d 2 (19)), little information is available about the nature of the B epitopes recognized by the IgE immunoglobulins. It has been suggested that allergenic proteins may share some common structural features capable of eliciting an IgE response (14) and also that sequence similarities between allergenic lipocalins could indicate putative IgE binding regions (19). To gain further insight into the nature of the IgE B epitopes, we describe here a crystallographic and immunochemical study of recombinant Equ c 1.…”

mentioning

confidence: 99%

“…The entry sites to the putative binding sites of Equ c 1 (loops L1, L3, and L5) are located on opposite sides of the dimer and are accessible for ligand binding. The tight association buries 1070 Å 2 of exposed molecular surface from each monomer (as calculated with the program (19), the retinol-binding protein (8), or the human neutrophil gelatinase-associated protein (31)), lipocalins often exist as dimers or higher oligomers. However, no consistent pattern of dimerization is obvious from the analysis of known three-dimensional structures.…”

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confidence: 99%

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Crystal Structure of the Allergen Equ c 1

Lascombe¹,

Grégoire²,

Poncet³

et al. 2000

Journal of Biological Chemistry

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The three-dimensional structure of the major horse allergen Equ c 1 has been determined at 2.3 Å resolution by x-ray crystallography. Equ c 1 displays the typical fold of lipocalins, a ␤-barrel flanked by a C-terminal ␣-helix. The space between the two ␤-sheets of the barrel defines an internal cavity that could serve, as in other lipocalins, for the binding and transport of small hydrophobic ligands. Equ c 1 crystallizes in a novel dimeric form, which is distinct from that observed in other lipocalin dimers and corresponds to the functional form of the allergen. Binding studies of point mutants of the allergen with specific monoclonal antibodies raised in mouse and IgE serum from horse allergic patients allowed to identify putative B cell antigenic determinants. In addition, total inhibition of IgE serum recognition by a single specific monoclonal antibody revealed the restricted nature of the IgE binding target on the molecular surface of Equ c 1.The incidence of allergic diseases is increasing in developed countries resulting from growing exposure to allergens, altered stimulation of the immune system during development, and probably facilitating an adjuvant effect of the environment. Allergy to animals is distinguishable by its intensity and the possibility of sensitization by a limited contact with danders or hair. The animals responsible for allergy are obviously familiar domestic cats and dogs, but also the horse, which is often incriminated. Five main horse allergens have been isolated and purified (1, 2). Among these, the Equ c 1 protein (molecular mass 21.5 kDa, 187 amino acids, pI ϭ 4.5) has been defined as a major allergen, because it induces an IgE-mediated type I allergic reaction in a majority of the patients allergic to horses.Equ c 1 belongs to the lipocalin family (3, 4). Although members of this family display low sequence similarity (often lower than 20% of amino acid identities), all share a conserved folding pattern, an 8-stranded ␤-barrel flanked by an ␣-helix at the C-terminal end of the polypeptide chain. The lipocalin ␤-barrel often defines a central apolar cavity that serves for the binding and transport of small hydrophobic molecules such as retinol (retinol-binding protein (5, 6)), odorant molecules (bovine odorant-binding protein (7, 8)), or pheromones (mouse major urinary protein, mMUP 1 (9), and rat urinary ␣2-globulin (10)). Several lipocalins have been described as allergenic proteins, among which the mouse major urinary protein mMUP (11), rat urinary ␣2-globulin rat urinary ␣2-globulin (12), bovine ␤-lactoglobulin (13), cockroach allergen Bla g 4 (14), dog allergens Can f 1 and Can f 2 (15), and bovine allergen Bos d 2 (16).Whether a protein exhibits special structural characteristics that are responsible for its allergenic properties is an issue that remains poorly understood. Although the three-dimensional structures of some allergenic lipocalins are known (mMUP (9), rat urinary ␣2-globulin (10), bovine ␤-lactoglobulin (17, 18), and Bos d 2 (19)), little information is availa...

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Structural and thermodynamic consequences of removal of a conserved disulfide bond from equine β‐lactoglobulin

et al. 2006

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A disulfide bond between cysteine 66 and cysteine 160 of equine beta-lactoglobulin was removed by substituting cysteine residues with alanine. This disulfide bond is conserved across the lipocalin family. The conformation and stability of the disulfide-deleted mutant protein was investigated by circular dichroism. The mutant protein assumes a native-like structure under physiological conditions and assumes a helix-rich molten globule structure at acid pH or at moderate concentrations of urea as the wild-type protein does. The urea-induced unfolding experiment shows that the stability of the native conformation was reduced but that of the molten globule intermediate is not significantly changed at pH 4 by removal of the disulfide bond. On the other hand, the molten globule at acid pH was destabilized by removal of the disulfide bond. This difference in the stabilizing effect of the disulfide bond was interpreted by the effect of the disulfide in keeping the molecule compact against the electrostatic repulsion at acid pH. In contrast to the wild-type protein, the circular dichroism spectrum in the molten globule state at acid pH depends on anion concentration, suggesting that the expansion of the molecule through electrostatic repulsion induces alpha-helices as observed in the cold denatured state of the wild-type protein.

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Probing the Molecular Basis of Allergy

Abstract: The three-dimensional structure of the major bovine allergen Bos d 2 has been determined by using x-ray diffraction at 1.

Cited by 74 publications

References 31 publications

The 1.8-Å Crystal Structure of Human Tear Lipocalin Reveals an Extended Branched Cavity with Capacity for Multiple Ligands

The 1.8-Å Crystal Structure of Human Tear Lipocalin Reveals an Extended Branched Cavity with Capacity for Multiple Ligands

Crystal Structure of the Allergen Equ c 1

Structural and thermodynamic consequences of removal of a conserved disulfide bond from equine β‐lactoglobulin

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