Creatine kinase/α-crystallin interaction functions in cataract development.

Autor: Hamilton PD; Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO, 63110, USA., Bozeman SL; Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO, 63110, USA., Andley UP; Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO, 63110, USA.
Jazyk: angličtina
Zdroj: Biochemistry and biophysics reports [Biochem Biophys Rep] 2020 Feb 29; Vol. 22, pp. 100748. Date of Electronic Publication: 2020 Feb 29 (Print Publication: 2020).
DOI: 10.1016/j.bbrep.2020.100748
Abstrakt: Creatine kinase (CK) is an energy storage enzyme that plays an important role in energy metabolism. CK/phosphocreatine functions as an energy buffer and links ATP production sites with ATP utilization sites. Several key mutations in the αA-crystallin ( cryaa ) and αB-crystallin ( cryab ) genes have been linked with autosomal-dominant, hereditary human cataracts. The cryaa-R49C mutation was identified in a four-generation Caucasian family. We previously identified an increase in the quantity of CK complexed with α-crystallin in the lenses of knock-in mice expressing the cryaa-R49C mutation using proteomic analyses. Increased levels of CK in postnatal cataractous lenses may indicate increased ATP requirements during early cataract development. To gain a further understanding of the relationship between CK and α-crystallin, we investigated whether α-crystallin interacts with and forms complexes with CK, in vitro . Isothermal titration calorimetry (ITC) showed that each CK dimer bound to 28 α-crystallin subunits, with a K d of 3.3 × 10 -7  M, and that the interaction between α-crystallin and CK was endothermic, thermodynamically favorable, and entropy-driven. High-salt concentrations did not affect the interaction between CK and α-crystallin, suggesting that the interaction between CK and α-crystallin is primarily hydrophobic. Gel permeation chromatography (GPC) detected water-soluble α-crystallin and CK complexes, as determined by increased light scattering after complex formation. In addition, CK and α-crystallin formed partially-water-insoluble, high-molecular-mass complexes. Enzyme-linked immunosorbent assay (ELISA)-based enzymatic activity analyses of lens homogenates showed a 17-fold increase in CK activity in the postnatal lenses of cryaa-R49C knock-in mice. These studies indicate that the interaction between α-crystallin and CK is functionally important and that increased CK levels may be necessary to meet the increased ATP demands of ATP-dependent functions in cataractous lenses.
(© 2020 The Author(s).)
Databáze: MEDLINE
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