Cataract-causing mutation S228P promotes βB1-crystallin aggregation and degradation by separating two interacting loops in C-terminal domain
Abstract β/γ-Crystallins are predominant structural proteins in the cytoplasm of lens fiber cells and share a similar fold composing of four Greek-key motifs divided into two domains. Numerous cataract-causing mutations have been identified in various β/γ-crystallins, but the mechanisms underlying c...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Oxford University Press
2016-06-01
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| Series: | Protein & Cell |
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| Online Access: | http://link.springer.com/article/10.1007/s13238-016-0284-3 |
| _version_ | 1827839033232850944 |
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| author | Liang-Bo Qi Li-Dan Hu Huihui Liu Hai-Yun Li Xiao-Yao Leng Yong-Bin Yan |
| author_facet | Liang-Bo Qi Li-Dan Hu Huihui Liu Hai-Yun Li Xiao-Yao Leng Yong-Bin Yan |
| author_sort | Liang-Bo Qi |
| collection | DOAJ |
| description | Abstract β/γ-Crystallins are predominant structural proteins in the cytoplasm of lens fiber cells and share a similar fold composing of four Greek-key motifs divided into two domains. Numerous cataract-causing mutations have been identified in various β/γ-crystallins, but the mechanisms underlying cataract caused by most mutations remains uncharacterized. The S228P mutation in βB1-crystallin has been linked to autosomal dominant congenital nuclear cataract. Here we found that the S228P mutant was prone to aggregate and degrade in both of the human and E. coli cells. The intracellular S228P aggregates could be redissolved by lanosterol. The S228P mutation modified the refolding pathway of βB1-crystallin by affecting the formation of the dimeric intermediate but not the monomeric intermediate. Compared with native βB1-crystallin, the refolded S228P protein had less packed structures, unquenched Trp fluorophores and increased hydrophobic exposure. The refolded S228P protein was prone to aggregate at the physiological temperature and decreased the protective effect of βB1-crystallin on βA3-crystallin. Molecular dynamic simulation studies indicated that the mutation decreased the subunit binding energy and modified the distribution of surface electrostatic potentials. More importantly, the mutation separated two interacting loops in the C-terminal domain, which shielded the hydrophobic core from solvent in native βB1-crystallin. These two interacting loops are highly conserved in both of the N- and C-terminal domains of all β/γ-crystallins. We propose that these two interacting loops play an important role in the folding and structural stability of β/γ-crystallin domains by protecting the hydrophobic core from solvent access. |
| first_indexed | 2024-03-12T07:15:37Z |
| format | Article |
| id | doaj.art-bb6a650120fe4b38a27e08468f2dfe84 |
| institution | Directory Open Access Journal |
| issn | 1674-800X 1674-8018 |
| language | English |
| last_indexed | 2024-03-12T07:15:37Z |
| publishDate | 2016-06-01 |
| publisher | Oxford University Press |
| record_format | Article |
| series | Protein & Cell |
| spelling | doaj.art-bb6a650120fe4b38a27e08468f2dfe842023-09-02T22:52:55ZengOxford University PressProtein & Cell1674-800X1674-80182016-06-017750151510.1007/s13238-016-0284-3Cataract-causing mutation S228P promotes βB1-crystallin aggregation and degradation by separating two interacting loops in C-terminal domainLiang-Bo Qi0Li-Dan Hu1Huihui Liu2Hai-Yun Li3Xiao-Yao Leng4Yong-Bin Yan5State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua UniversityState Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua UniversityState Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua UniversityState Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua UniversityState Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua UniversityState Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua UniversityAbstract β/γ-Crystallins are predominant structural proteins in the cytoplasm of lens fiber cells and share a similar fold composing of four Greek-key motifs divided into two domains. Numerous cataract-causing mutations have been identified in various β/γ-crystallins, but the mechanisms underlying cataract caused by most mutations remains uncharacterized. The S228P mutation in βB1-crystallin has been linked to autosomal dominant congenital nuclear cataract. Here we found that the S228P mutant was prone to aggregate and degrade in both of the human and E. coli cells. The intracellular S228P aggregates could be redissolved by lanosterol. The S228P mutation modified the refolding pathway of βB1-crystallin by affecting the formation of the dimeric intermediate but not the monomeric intermediate. Compared with native βB1-crystallin, the refolded S228P protein had less packed structures, unquenched Trp fluorophores and increased hydrophobic exposure. The refolded S228P protein was prone to aggregate at the physiological temperature and decreased the protective effect of βB1-crystallin on βA3-crystallin. Molecular dynamic simulation studies indicated that the mutation decreased the subunit binding energy and modified the distribution of surface electrostatic potentials. More importantly, the mutation separated two interacting loops in the C-terminal domain, which shielded the hydrophobic core from solvent in native βB1-crystallin. These two interacting loops are highly conserved in both of the N- and C-terminal domains of all β/γ-crystallins. We propose that these two interacting loops play an important role in the folding and structural stability of β/γ-crystallin domains by protecting the hydrophobic core from solvent access.http://link.springer.com/article/10.1007/s13238-016-0284-3β/γ-crystallincataract-causing mutationhydrophobic coreprotein aggregationprotein folding |
| spellingShingle | Liang-Bo Qi Li-Dan Hu Huihui Liu Hai-Yun Li Xiao-Yao Leng Yong-Bin Yan Cataract-causing mutation S228P promotes βB1-crystallin aggregation and degradation by separating two interacting loops in C-terminal domain Protein & Cell β/γ-crystallin cataract-causing mutation hydrophobic core protein aggregation protein folding |
| title | Cataract-causing mutation S228P promotes βB1-crystallin aggregation and degradation by separating two interacting loops in C-terminal domain |
| title_full | Cataract-causing mutation S228P promotes βB1-crystallin aggregation and degradation by separating two interacting loops in C-terminal domain |
| title_fullStr | Cataract-causing mutation S228P promotes βB1-crystallin aggregation and degradation by separating two interacting loops in C-terminal domain |
| title_full_unstemmed | Cataract-causing mutation S228P promotes βB1-crystallin aggregation and degradation by separating two interacting loops in C-terminal domain |
| title_short | Cataract-causing mutation S228P promotes βB1-crystallin aggregation and degradation by separating two interacting loops in C-terminal domain |
| title_sort | cataract causing mutation s228p promotes βb1 crystallin aggregation and degradation by separating two interacting loops in c terminal domain |
| topic | β/γ-crystallin cataract-causing mutation hydrophobic core protein aggregation protein folding |
| url | http://link.springer.com/article/10.1007/s13238-016-0284-3 |
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