4IGX

Crystal structure of kirola (Act d 11) - triclinic form

Summary for 4IGX

• Entry DOI: 10.2210/pdb4igx/pdb
• Related: 4IGV 4IGW 4IGY 4IH0 4IH2 4IHR
• Descriptor: Kirola, UNKNOWN LIGAND, CHLORIDE ION, ... (5 entities in total)
• Functional Keywords: mlp/rrp family, pr-10 related, allergen
• Biological source: Actinidia deliciosa (Chinese gooseberry,kiwifruit)
• Total number of polymer chains: 4
• Total formula weight: 69824.83

Authors

Chruszcz, M.,Ciardiello, M.A.,Giangrieco, I.,Osinski, T.,Minor, W. (deposition date: 2012-12-18, release date: 2013-09-04, Last modification date: 2023-09-20)

Primary citation

Chruszcz, M.,Ciardiello, M.A.,Osinski, T.,Majorek, K.A.,Giangrieco, I.,Font, J.,Breiteneder, H.,Thalassinos, K.,Minor, W.
Structural and bioinformatic analysis of the kiwifruit allergen Act d 11, a member of the family of ripening-related proteins.
Mol.Immunol., 56:794-803, 2013

PubMed Abstract: The allergen Act d 11, also known as kirola, is a 17 kDa protein expressed in large amounts in ripe green and yellow-fleshed kiwifruit. Ten percent of all kiwifruit-allergic individuals produce IgE specific for the protein. Using X-ray crystallography, we determined the first three-dimensional structures of Act d 11, produced from both recombinant expression in Escherichia coli and from the natural source (kiwifruit). While Act d 11 is immunologically correlated with the birch pollen allergen Bet v 1 and other members of the pathogenesis-related protein family 10 (PR-10), it has low sequence similarity to PR-10 proteins. By sequence Act d 11 appears instead to belong to the major latex/ripening-related (MLP/RRP) family, but analysis of the crystal structures shows that Act d 11 has a fold very similar to that of Bet v 1 and other PR-10 related allergens regardless of the low sequence identity. The structures of both the natural and recombinant protein include an unidentified ligand, which is relatively small (about 250 Da by mass spectrometry experiments) and most likely contains an aromatic ring. The ligand-binding cavity in Act d 11 is also significantly smaller than those in PR-10 proteins. The binding of the ligand, which we were not able to unambiguously identify, results in conformational changes in the protein that may have physiological and immunological implications. Interestingly, the residue corresponding to Glu45 in Bet v 1 (Glu46), which is important for IgE binding to the birch pollen allergen, is conserved in Act d 11, even though it is not in other allergens with significantly higher sequence identity to Bet v 1. We suggest that the so-called Gly-rich loop (or P-loop), which is conserved in all PR-10 allergens, may be responsible for IgE cross-reactivity between Bet v 1 and Act d 11.

PubMed: 23969108
DOI: 10.1016/j.molimm.2013.07.004

Experimental method

X-RAY DIFFRACTION (2.35 Å)