Abstract | PURPOSE:
Cataracts are a major cause of blindness worldwide. A potential mechanism for loss of visual acuity may be due to light scattering from disruption of normal protein- protein interactions. During aging, the lens accumulates extensively deamidated crystallins. We have previously reported that deamidation in the betaA3-crystallin (betaA3) dimer decreased the stability of the dimer in vitro. The purpose of the present study was to investigate if deamidation altered the interaction of betaA3 with other beta-crystallin subunits. METHODS: Deamidation was mimicked by replacing glutamines, Q85 and Q180, at the predicted interacting interface between betaA3 domains with glutamic acids by site-directed mutagenesis. Human recombinant wild type betaA3 or the doubly deamidated mutant betaA3 Q85E/Q180E (DM betaA3) were mixed with either betaB1- or betaB2-crystallin (betaB1 or betaB2) subunits. After incubation at increasing temperatures, hetero-oligomers were resolved from individual subunits and their molar masses determined by size exclusion chromatography with in line multiangle laser light scattering. Structural changes of hetero-oligomers were analyzed with fluorescence spectroscopy and blue-native PAGE. RESULTS: Molar masses of the hetero-oligomer complexes indicated betaA3 formed a polydispersed hetero-tetramer with betaB1 and a mondispersed hetero-dimer with betaB2. Deamidation at the interface in the betaA3 dimer decreased formation of the hetero-oligomer with betaB1 and further decreased formation of the hetero-dimer with betaB2. During thermal-induced denaturation of the deamidated betaA3 dimer, betaB1 but not betaB2 was able to prevent precipitation of betaA3. CONCLUSIONS:
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Authors | Takumi Takata, Luke G Woodbury, Kirsten J Lampi |
Journal | Molecular vision
(Mol Vis)
Vol. 15
Pg. 241-9
( 2009)
ISSN: 1090-0535 [Electronic] United States |
PMID | 19190732
(Publication Type: Journal Article, Research Support, N.I.H., Extramural)
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Chemical References |
- CRYBA1 protein, human
- CRYBB1 protein, human
- beta-Crystallin A Chain
- beta-Crystallin B Chain
- beta-crystallin B2
- Glutamine
- Glutamic Acid
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Topics |
- Amino Acid Substitution
- Chromatography, Gel
- Circular Dichroism
- Glutamic Acid
(chemistry)
- Glutamine
(chemistry)
- Humans
- Protein Multimerization
- Protein Structure, Quaternary
- Scattering, Radiation
- beta-Crystallin A Chain
(chemistry, genetics, metabolism)
- beta-Crystallin B Chain
(chemistry, genetics, metabolism)
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