Limits...
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.


(a) The ribbon representation for monomeric Bos d 2. The eight antiparallel β-strands (A–H) forming a central barrel are shown as cyan arrows. The β-strand (I) outside the barrel is in green. The α-helix is in red and loops connecting different secondary structure elements are labelled L1 to L8. The black arrow shows the entrance to the ligand binding pocket (b) The monomers of 9 different lipocalin allergens which form symmetric homodimers are superimposed to observe the orientation of the second monomer. The superimposed monomers are in green and grey, blue and red colours are used for the second monomers.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4561914&req=5

f1: (a) The ribbon representation for monomeric Bos d 2. The eight antiparallel β-strands (A–H) forming a central barrel are shown as cyan arrows. The β-strand (I) outside the barrel is in green. The α-helix is in red and loops connecting different secondary structure elements are labelled L1 to L8. The black arrow shows the entrance to the ligand binding pocket (b) The monomers of 9 different lipocalin allergens which form symmetric homodimers are superimposed to observe the orientation of the second monomer. The superimposed monomers are in green and grey, blue and red colours are used for the second monomers.

Mentions: Lipocalins include the most important inhalant animal allergens. In addition, a bovine milk allergen (Bos d 5) and several arthropodan allergens are lipocalins. Lipocalins are typically small proteins (about 200 amino acid residues) composed of an 8-stranded up-and-down antiparallel β-barrel and one α-helix. There is a hydrophobic cavity inside the β-barrel capable of binding a hydrophobic or amphiphilic ligand (Fig. 1a). In most cases, the native ligands for lipocalins are unknown45. In order to analyze the oligomeric structures of lipocalins, we have studied all 10 crystal structures of lipocalin allergens in the Protein Data Bank (PDB). Bovine dander allergen Bos d 2 was the only one found to be monomeric6. Because the protein had been crystallised at an acidic pH (3.4–4.5)7, we decided to search for a new crystal form at a more neutral pH. In fact, both new crystal forms of Bos d 2 contained a symmetric weak dimer. The existence of a dimeric Bos d 2 in solution was observed by native mass spectrometry (MS). Furthermore, we used native MS to quantify the dimerization for Bos d 2 and Bos d 5. In the following, we present an analysis of oligomeric structures of lipocalin allergens and discuss their implications for the presentation of multiple epitopes and the triggering of FcεRI bound IgE antibodies on mast-cells and basophils.


Dimerization of lipocalin allergens.

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

(a) The ribbon representation for monomeric Bos d 2. The eight antiparallel β-strands (A–H) forming a central barrel are shown as cyan arrows. The β-strand (I) outside the barrel is in green. The α-helix is in red and loops connecting different secondary structure elements are labelled L1 to L8. The black arrow shows the entrance to the ligand binding pocket (b) The monomers of 9 different lipocalin allergens which form symmetric homodimers are superimposed to observe the orientation of the second monomer. The superimposed monomers are in green and grey, blue and red colours are used for the second monomers.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f1: (a) The ribbon representation for monomeric Bos d 2. The eight antiparallel β-strands (A–H) forming a central barrel are shown as cyan arrows. The β-strand (I) outside the barrel is in green. The α-helix is in red and loops connecting different secondary structure elements are labelled L1 to L8. The black arrow shows the entrance to the ligand binding pocket (b) The monomers of 9 different lipocalin allergens which form symmetric homodimers are superimposed to observe the orientation of the second monomer. The superimposed monomers are in green and grey, blue and red colours are used for the second monomers.
Mentions: Lipocalins include the most important inhalant animal allergens. In addition, a bovine milk allergen (Bos d 5) and several arthropodan allergens are lipocalins. Lipocalins are typically small proteins (about 200 amino acid residues) composed of an 8-stranded up-and-down antiparallel β-barrel and one α-helix. There is a hydrophobic cavity inside the β-barrel capable of binding a hydrophobic or amphiphilic ligand (Fig. 1a). In most cases, the native ligands for lipocalins are unknown45. In order to analyze the oligomeric structures of lipocalins, we have studied all 10 crystal structures of lipocalin allergens in the Protein Data Bank (PDB). Bovine dander allergen Bos d 2 was the only one found to be monomeric6. Because the protein had been crystallised at an acidic pH (3.4–4.5)7, we decided to search for a new crystal form at a more neutral pH. In fact, both new crystal forms of Bos d 2 contained a symmetric weak dimer. The existence of a dimeric Bos d 2 in solution was observed by native mass spectrometry (MS). Furthermore, we used native MS to quantify the dimerization for Bos d 2 and Bos d 5. In the following, we present an analysis of oligomeric structures of lipocalin allergens and discuss their implications for the presentation of multiple epitopes and the triggering of FcεRI bound IgE antibodies on mast-cells and basophils.

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.