Solution structure of the major fish allergen parvalbumin Sco j 1 derived from the Pacific mackerel

Abstract

Although fish is an important part of the human diet, it is also a common source of food allergy. The major allergen in fish is parvalbumin, a well-conserved Ca2+-binding protein found in the white muscle of many fish species. Here, we studied the solution structure of the parvalbumin Sco j 1, derived from the Pacific mackerel, using nuclear magnetic resonance spectroscopy. We mapped the IgE-binding epitope proposed in a recent study onto the present structure. Interestingly, three of four residues, which were elucidated as key residues of the IgE-binding epitope, were exposed to solvent, whereas one residue faced the inside of the molecule. We expect that this solution structure can be used in future studies attempting to analyze the various IgE-binding modes of these allergens.

Reconstruction of fish allergenicity from the content and structural traits of the component β-parvalbumin isoforms

“…4a and 4b show that freshly prepared Ca 2+ -bound proteins cooperatively folded with predominant αhelical secondary structures and hydrodynamic radii close to the R H T of spherical monomers (1.6 ± 0.1 nm). These observations agree with the available 3D structures of gmPV1 and sjPV1 26,43 . However, despite these similarities, Ca 2+ -bound sjPV1 and gmPV2 unfolded at a significantly lower temperature than the other chains ( Fig.…”

“…All chains shared C19, three of the chains (gmPV2, sjPV1 and sjPV2) also contained C34, and gmPV2 also had C12, which suggested differences in their capacity to form disulfide-bonded species and aggregated polymorphs 44 . It must also be noted that K29, which is only present in sjPV1, was suggested to be part of an IgE conformational epitope in this protein 43 . All chains were produced as recombinant proteins and purified as Ca 2+ -bound forms using established protocols 25,45 .…”

Reconstruction of fish allergenicity from the content and structural traits of the component β-parvalbumin isoforms

“…The pairwise identity of proteins varied from 70.6% in Gadus morhua to 81.6% in Scomber japonicus . Sequence differences were mainly found at the N-terminal half of the chains, overlapping with the predicted PARV19 36 epitope, the most common IgE immunoreactive region (IgE-I) 3,4,25,43 , the N-terminal EF-hand (AB region) and the amyloid forming segments of gmPV1 25,30 . Despite the sequence differences, the AmyloPred2 algorithm revealed several regions with aggregation potential in all chains (Fig.…”

“…All chains shared C19, three of the chains (gmPV2, sjPV1 and sjPV2) also contained C34, and gmPV2 also had C12, which suggested differences in their capacity to form disulfide-bonded species and aggregated polymorphs 44 . It must also be noted that K29, which is only present in sjPV1, was suggested to be part of an IgE conformational epitope in this protein 43 . All chains were produced as recombinant proteins and purified as Ca 2+ -bound forms using established protocols 25,45 .

Figure 1Sequences of the β-PV isoforms of Gadus morhua and Scomber japonicus .

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“…( d ) Segments involved in the globular and amyloid folds of β-PV. The globular fold contains three helix-loop-helix (AB, CD and EF) EF-hands, of which only CD and EF bind cations 3,4,26,43 . Regions assembling into amyloids were predicted by AmylPred2, and they are depicted by arrows.…”