Article Eye lens 0-crystallins are predicted by native ion mobility-mass spectrometry and computations to form compact higher-ordered heterooligomers

Eye lens a-and 0-/y-crystallin proteins are not replaced after fiber cell denucleation and maintain lens transparency and refractive properties. The exceptionally high (-400-500 mg/mL) concentration of crystallins in mature lens tissue and multiple other factors impede precise characterization of 0-crystallin interactions, oligomer composition, size, and topology. Native ion mobility-mass spectrometry is used here to probe 0-crystallin association and provide insight into homo-and heterooligomerization kinetics for these proteins. These experiments include separation and characterization of higher-order 0-crystallin oligomers and illustrate the unique advantages of native IM-MS. Recombinantly expressed 0B1, 0B2, and 0A3 isoforms are found to have different homodimerization propensities, and only 0A3 forms larger homooligomers. Heterodimerization of 0B2 with 0A3 occurs -3 times as fast as that of 0B1 with 0A3, and 0B1 and 0B2 heterodimerize less readily. Ion mobility experiments, molecular dynamics simulations, and PISA analysis together reveal that observed oligomers are consistent with predominantly compact, ringlike topologies.

Automated summary

This study investigates the interactions and oligomerization kinetics of β-crystallin in the lens using native ion mobility-mass spectrometry, revealing compact ring-like topologies of the observed oligomers.