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Unlocking the secrets of the eye’s proteins

A new understanding of how proteins in the eye are prevented from clumping together has opened up new possibilities for the prevention and treatment of cataracts.

Researchers from the Technical University of Munich (TUM) have identified the precise structure of the alpha-A-crystallin protein, one of the protective proteins in the lens of the human eye that prevents other proteins from being damaged. Proteins in the eye are created during embryotic development and do not replenish throughout life, making the role of the protective proteins very important to ongoing eye health.

Attempts to determine the structure of alpha-A-crystallin had been previously unsuccessful due to its complex structure, however TUM researchers were able to combine cryo-electron microscopy, mass spectrometry, NMR spectroscopy and molecular modelling to develop a model.

“Alpha-A-crystallin is extremely multifaceted,” Professor Sevil Weinkauf, one of the researchers behind the project, said.

“This makes it very difficult to determine its structure. It was only after developing a new strategy for data analysis that we were able to demonstrate that in solution it takes on different structures with 12, 16 or 20 subunits.”

The team has speculated that alpha-A-crystallin may play a role in protecting other proteins from disulfide bridges, which impacts on various properties of the protein molecule.

It is even though that alpha-A-crystallin could transfer existing disulfide bridges to other proteins.

“This ability corresponds to that of a protein disulfide oxidase,” Dr Christoph Kaiser, one of the lead authors on the project, said.

“Alpha-A-crystallin can thus influence the redox state of other lens proteins. This function also explains why roughly half of the alpha-A-crystallins in embryos already have such disulfide bridges.”

The team hopes that this improved understanding of how proteins in the eye work could for the bases for therapies targeting cataracts.

The research was recently published in the journal Nature Structural and Molecular Biology.