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Updated: May 11, 2026

On-Chip Crystallization and Large-Scale Serial Diffraction at Room Temperature
Published on: March 11, 2022
A novel interdomain interface in crystallins: structural characterization of the βγ-crystallin from Geodia cydonium
Alessandro Vergara1, Marco Grassi, Filomena Sica
1Department of Chemical Sciences, University of Naples 'Federico II', Via Cintia, I-80126 Napoli, Italy.
Abstract:
The βγ-crystallin superfamily includes highly diverse proteins belonging to all of the kingdoms of life. Based on structural topology, these proteins are considered to be evolutionarily related to the long-lived βγ-crystallins that constitute the vertebrate eye lens. This study reports the crystallographic structure at 0.99 Å resolution of the two-domain βγ-crystallin (geodin) from the sponge Geodia cydonium. This is the most ancient member of the βγ-crystallin superfamily in metazoans. The X-ray structure shows that the geodin domains adopt the typical βγ-crystallin fold with a paired Greek-key motif, thus confirming the hypothesis that the crystallin-type scaffold used in the evolution of bacteria and moulds was recruited very early in metazoans. As a significant new structural feature, the sponge protein possesses a unique interdomain interface made up by pairing between the second motif of the first domain and the first motif of the second domain. The atomic resolution also allowed a detailed analysis of the calcium-binding site of the protein.
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