3D structure of the native α-crystallin from bovine eye lens

• Published in: International journal of biological macromolecules 2018-10, Vol.117, p.1289-1298
• Main Authors: Ryazantsev, Sergey N., Poliansky, Nikolai B., Chebotareva, Natalia A., Muranov, Konstantin O.
• Format: Article
• Language: English
• Subjects: 3D structure; alpha-Crystallins - chemistry; alpha-Crystallins - ultrastructure; Analytical ultracentrifugation; Animals; Cattle; Chromatography, Gel; Crystallins - chemistry; Dynamic Light Scattering; Electron microscopy; Models, Molecular; Protein Conformation; Temperature; Ultracentrifugation; α-Crystallin
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2018.06.004

α-Crystallin is the major eye lens protein that has been shown to support lens transparency by preventing the aggregation of lens proteins. The 3D structure of α-crystallin is largely unknown. Electron microscopy, single-particle 3D reconstruction, size exclusion chromatography, dynamic light scattering, and analytical ultracentrifugation were used to study the structure of the native α-crystallin. Native α-crystallin has a wide distribution in size. The shape of mass distribution is temperature-dependent, but the oligomers with a sedimentation coefficient of ~22 S (750–830 kDa) strongly prevailed at all temperatures used. A 3D model of native α-crystallin with resolution of ~2 nm was created. The model is asymmetrical, has an elongated bean-like shape 13 × 19 nm with a dense core and filamentous “kernel”. It does not contain a central cavity. The majority of α-crystallin particles regardless of experimental conditions are 13 × 19 nm, which corresponds to 22S sedimentation coefficient, hydrodynamic diameter 20 nm and mass of 750–830 kD. These particles are in dynamic equilibrium with particles of smaller and larger sizes. •The native lens α-crystallin are particles of size 5–20 nm.•The particles 12–14 nm in diameter (750–830 kDa) are dominant.•Changing conditions cause the rearrangement of the α-crystallin oligomer.•3D model is asymmetrical, elongated, with a dense core and filamentous “kernel.”•Damaged protein is buried inside the particle by a dynamic exchange of α-crystallin.