Changes in solvent accessibility of wild-type and deamidated βB2-crystallin following complex formation with αA-crystallin

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9 Scopus citations

Abstract

Aberrant protein interactions can lead to aggregation and insolubilization, such as occurs during cataract formation. Deamidation, a prevalent age-related modification in the lens of the eye, decreases stability of the major lens proteins, crystallins. The mechanism of deamidation altering interactions between αA-crystallin and βB2-crystallin was investigated by detecting changes in solvent accessibility upon complex formation during heating. Solvent accessibility was determined by measuring hydrogen/deuterium exchange levels of backbone amides by high-resolution mass spectrometry. Deuterium levels in wild type βB2-crystallin increased 50-60% in both domains following complex formation with αA-crystallin. This increased solvent accessibility indicated a general loosening along the backbone amides. Peptides with the greatest deuterium increases were located at the buried monomer-monomer interface, suggesting that the βB2 dimer was disrupted. The only region where the deuterium levels decreased was in βB2 peptide 123-139, containing an outside loop, and may be a potential site of interaction with αA. Mimicking deamidation at the βB2 dimer interface prevented complex formation with αA. When temperatures were lowered, an αA/βB2 Q70E/Q162E complex formed with similar solvent accessibilities as αA/WT βB2. Deamidation did not disrupt specific αA/βB2 interactions but favored aggregation before complex formation with αA. We conclude that deamidation contributes to cataract formation through destabilization of crystallins before they can be rescued by α-crystallin.

Original languageEnglish (US)
Pages (from-to)48-58
Number of pages11
JournalExperimental Eye Research
Volume104
DOIs
StatePublished - Nov 2012

Keywords

  • Age-related modifications
  • Alpha-crystallin
  • Beta-crystallins
  • Cataracts
  • Crystallins
  • Deamdidation
  • Lens

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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