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Dimerization of lipocalin allergens.

Niemi MH, Rytkönen-Nissinen M, Miettinen I, Jänis J, Virtanen T, Rouvinen J - Sci Rep (2015)

Bottom Line: We have determined two different dimeric crystal structures for bovine dander lipocalin Bos d 2, which was earlier described as a monomeric allergen.The crystal structure analysis of all other determined lipocalin allergens also revealed oligomeric structures which broadly utilize inherent structural features of the β-sheet in dimer formation.According to the moderate size of monomer-monomer interfaces, most of these dimers would be transient in solution.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry and Biocenter Kuopio, University of Eastern Finland, PO BOX 111, 80101 Joensuu, Finland.

ABSTRACT
Lipocalins are one of the most important groups of inhalant animal allergens. The analysis of structural features of these proteins is important to get insights into their allergenicity. We have determined two different dimeric crystal structures for bovine dander lipocalin Bos d 2, which was earlier described as a monomeric allergen. The crystal structure analysis of all other determined lipocalin allergens also revealed oligomeric structures which broadly utilize inherent structural features of the β-sheet in dimer formation. According to the moderate size of monomer-monomer interfaces, most of these dimers would be transient in solution. Native mass spectrometry was employed to characterize quantitatively transient dimerization of two lipocalin allergens, Bos d 2 and Bos d 5, in solution.

No MeSH data available.


Dimerization of Bos d 2 observed in crystals as a ribbon presentation.(a) The symmetric dimer of Bos d 2 observed in the monoclinic (C2) crystal form, (b) in the trigonal (P3221) crystal form. The key residues which contribute to the binding on the monomer-monomer interface in Bos d 2 dimer in monoclinic (c) and in trigonal (d) crystal forms. (e) The superimposition of a Cα-backbone of monomeric Bos d 2 (orthorhombic, in red), dimeric Bos d 2 (monoclinic, in cyan), and dimeric Bos d 2 (trigonal, in grey).
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f2: Dimerization of Bos d 2 observed in crystals as a ribbon presentation.(a) The symmetric dimer of Bos d 2 observed in the monoclinic (C2) crystal form, (b) in the trigonal (P3221) crystal form. The key residues which contribute to the binding on the monomer-monomer interface in Bos d 2 dimer in monoclinic (c) and in trigonal (d) crystal forms. (e) The superimposition of a Cα-backbone of monomeric Bos d 2 (orthorhombic, in red), dimeric Bos d 2 (monoclinic, in cyan), and dimeric Bos d 2 (trigonal, in grey).

Mentions: The search for new crystal forms for bovine allergen Bos d 2 at neutral pH resulted in two new crystal forms. Monoclinic crystals diffracted at a 1.4 Å resolution. The asymmetric unit contained one Bos d 2 molecule but the space group C2 includes a 2-fold symmetry axis, consequently, half of the dimer can be formed by a crystallographic symmetry operator. Trigonal crystals diffracted at 1.75 Å resolution. Again, the asymmetric unit contained one Bos d 2 molecule and a dimer can be formed with the use of a crystallographic symmetry operator. Bos d 2 contains a central β-barrel composing of eight antiparallel β-strands (A-H). In addition, there is a short β-strand (I) as well as an α-helix (Fig. 1a). The r.m.s. differences of Bos d 2 molecules in orthorhombic and monoclinic crystals is 0.226 Å, between orthorhombic and triclinic crystals there is 0.297 Å and between monoclinic and triclinic crystals there is 0.242 Å, which are in the range observed for different molecules in the asymmetric unit in protein crystal structures. The largest changes in the structures are located in the L3 loop and the L8 loop that connects the C-terminus of β-strand H to the α-helix (Fig. 2e).


Dimerization of lipocalin allergens.

Niemi MH, Rytkönen-Nissinen M, Miettinen I, Jänis J, Virtanen T, Rouvinen J - Sci Rep (2015)

Dimerization of Bos d 2 observed in crystals as a ribbon presentation.(a) The symmetric dimer of Bos d 2 observed in the monoclinic (C2) crystal form, (b) in the trigonal (P3221) crystal form. The key residues which contribute to the binding on the monomer-monomer interface in Bos d 2 dimer in monoclinic (c) and in trigonal (d) crystal forms. (e) The superimposition of a Cα-backbone of monomeric Bos d 2 (orthorhombic, in red), dimeric Bos d 2 (monoclinic, in cyan), and dimeric Bos d 2 (trigonal, in grey).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4561914&req=5

f2: Dimerization of Bos d 2 observed in crystals as a ribbon presentation.(a) The symmetric dimer of Bos d 2 observed in the monoclinic (C2) crystal form, (b) in the trigonal (P3221) crystal form. The key residues which contribute to the binding on the monomer-monomer interface in Bos d 2 dimer in monoclinic (c) and in trigonal (d) crystal forms. (e) The superimposition of a Cα-backbone of monomeric Bos d 2 (orthorhombic, in red), dimeric Bos d 2 (monoclinic, in cyan), and dimeric Bos d 2 (trigonal, in grey).
Mentions: The search for new crystal forms for bovine allergen Bos d 2 at neutral pH resulted in two new crystal forms. Monoclinic crystals diffracted at a 1.4 Å resolution. The asymmetric unit contained one Bos d 2 molecule but the space group C2 includes a 2-fold symmetry axis, consequently, half of the dimer can be formed by a crystallographic symmetry operator. Trigonal crystals diffracted at 1.75 Å resolution. Again, the asymmetric unit contained one Bos d 2 molecule and a dimer can be formed with the use of a crystallographic symmetry operator. Bos d 2 contains a central β-barrel composing of eight antiparallel β-strands (A-H). In addition, there is a short β-strand (I) as well as an α-helix (Fig. 1a). The r.m.s. differences of Bos d 2 molecules in orthorhombic and monoclinic crystals is 0.226 Å, between orthorhombic and triclinic crystals there is 0.297 Å and between monoclinic and triclinic crystals there is 0.242 Å, which are in the range observed for different molecules in the asymmetric unit in protein crystal structures. The largest changes in the structures are located in the L3 loop and the L8 loop that connects the C-terminus of β-strand H to the α-helix (Fig. 2e).

Bottom Line: We have determined two different dimeric crystal structures for bovine dander lipocalin Bos d 2, which was earlier described as a monomeric allergen.The crystal structure analysis of all other determined lipocalin allergens also revealed oligomeric structures which broadly utilize inherent structural features of the β-sheet in dimer formation.According to the moderate size of monomer-monomer interfaces, most of these dimers would be transient in solution.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry and Biocenter Kuopio, University of Eastern Finland, PO BOX 111, 80101 Joensuu, Finland.

ABSTRACT
Lipocalins are one of the most important groups of inhalant animal allergens. The analysis of structural features of these proteins is important to get insights into their allergenicity. We have determined two different dimeric crystal structures for bovine dander lipocalin Bos d 2, which was earlier described as a monomeric allergen. The crystal structure analysis of all other determined lipocalin allergens also revealed oligomeric structures which broadly utilize inherent structural features of the β-sheet in dimer formation. According to the moderate size of monomer-monomer interfaces, most of these dimers would be transient in solution. Native mass spectrometry was employed to characterize quantitatively transient dimerization of two lipocalin allergens, Bos d 2 and Bos d 5, in solution.

No MeSH data available.