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Non-Native Conformational Isomers of the Catalytic Domain of PCSK9 Induce an Immune Response, Reduce Lipids and Increase LDL Receptor Levels. Int J Mol Sci 2018; 19:ijms19020640. [PMID: 29495280 PMCID: PMC5855862 DOI: 10.3390/ijms19020640] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 02/16/2018] [Accepted: 02/19/2018] [Indexed: 12/15/2022] Open
Abstract
PCSK9 (Proprotein convertase subtilisin/kexin type 9) increases plasma cholesterol levels by promoting LDL receptor degradation. Current antibody inhibitors block the interaction between PCSK9 and LDL receptors, significantly decrease plasma cholesterol levels, and provide beneficial clinical outcomes. To reduce the action of PCSK9 in plasma, a novel strategy that will produce a panel of non-native, conformationally-altered isomers of PCSK9 (X-PCSK9) to develop active immunotherapy targeting of native PCSK9 and inhibiting/blocking the interaction of PCSK9 with LDL receptor, thus decreasing plasma cholesterol levels is proposed. The authors used the scrambled disulfide bond technique to generate conformationally-altered isomers of the catalytic domain of mouse PCSK9. The focus was on the immune response of four X-isomers and their effects on plasma cholesterol and triglyceride levels in both C57BL/6J and Apoe−/− mice. The authors showed that the four immunogens produced significant immunogenicity against native PCSK9 to day 120 after immunization of C57BL/6J and Apoe−/− mice. This resulted in significantly decreased plasma cholesterol levels in C57BL/6J mice, and to a lesser degree in Apoe−/− mice. The X-PCSK9-B1 treated mice had increased LDL receptor mRNA and protein levels at day 120 after treatment. Thus, this study provides a new, potentially promising approach that uses long-term immunotherapy for a treatment of hypercholesterolemia.
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Lee S, Wang C, Liu H, Xiong J, Jiji R, Hong X, Yan X, Chen Z, Hammel M, Wang Y, Dai S, Wang J, Jiang C, Zhang G. Hydrogen bonds are a primary driving force for de novo protein folding. Acta Crystallogr D Struct Biol 2017; 73:955-969. [PMID: 29199976 PMCID: PMC5713874 DOI: 10.1107/s2059798317015303] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2017] [Accepted: 10/20/2017] [Indexed: 01/09/2023] Open
Abstract
The protein-folding mechanism remains a major puzzle in life science. Purified soluble activation-induced cytidine deaminase (AID) is one of the most difficult proteins to obtain. Starting from inclusion bodies containing a C-terminally truncated version of AID (residues 1-153; AID153), an optimized in vitro folding procedure was derived to obtain large amounts of AID153, which led to crystals with good quality and to final structural determination. Interestingly, it was found that the final refolding yield of the protein is proline residue-dependent. The difference in the distribution of cis and trans configurations of proline residues in the protein after complete denaturation is a major determining factor of the final yield. A point mutation of one of four proline residues to an asparagine led to a near-doubling of the yield of refolded protein after complete denaturation. It was concluded that the driving force behind protein folding could not overcome the cis-to-trans proline isomerization, or vice versa, during the protein-folding process. Furthermore, it was found that successful refolding of proteins optimally occurs at high pH values, which may mimic protein folding in vivo. It was found that high pH values could induce the polarization of peptide bonds, which may trigger the formation of protein secondary structures through hydrogen bonds. It is proposed that a hydrophobic environment coupled with negative charges is essential for protein folding. Combined with our earlier discoveries on protein-unfolding mechanisms, it is proposed that hydrogen bonds are a primary driving force for de novo protein folding.
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Affiliation(s)
- Schuyler Lee
- Department of Biomedical Research, National Jewish Health, Denver, CO 80206, USA
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Denver, Aurora, CO 80206, USA
| | - Chao Wang
- Department of Biomedical Research, National Jewish Health, Denver, CO 80206, USA
| | - Haolin Liu
- Department of Biomedical Research, National Jewish Health, Denver, CO 80206, USA
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Denver, Aurora, CO 80206, USA
| | - Jian Xiong
- Department of Chemistry, University of Missouri, Columbus, Mississippi, USA
| | - Renee Jiji
- Department of Chemistry, University of Missouri, Columbus, Mississippi, USA
| | - Xia Hong
- Department of Biomedical Research, National Jewish Health, Denver, CO 80206, USA
| | - Xiaoxue Yan
- Department of Biomedical Research, National Jewish Health, Denver, CO 80206, USA
| | - Zhangguo Chen
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Denver, Aurora, CO 80206, USA
| | - Michal Hammel
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Yang Wang
- Department of Biomedical Research, National Jewish Health, Denver, CO 80206, USA
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Denver, Aurora, CO 80206, USA
| | - Shaodong Dai
- Department of Biomedical Research, National Jewish Health, Denver, CO 80206, USA
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Denver, Aurora, CO 80206, USA
| | - Jing Wang
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Denver, Aurora, CO 80206, USA
| | - Chengyu Jiang
- Department of Biochemistry and Molecular Biology, Peking Union Medical College, Beijing 100005, People’s Republic of China
| | - Gongyi Zhang
- Department of Biomedical Research, National Jewish Health, Denver, CO 80206, USA
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Denver, Aurora, CO 80206, USA
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Shinozaki R, Iwaoka M. Effects of Metal Ions, Temperature, and a Denaturant on the Oxidative Folding Pathways of Bovine α-Lactalbumin. Int J Mol Sci 2017; 18:ijms18091996. [PMID: 28926961 PMCID: PMC5618645 DOI: 10.3390/ijms18091996] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 09/11/2017] [Accepted: 09/13/2017] [Indexed: 12/02/2022] Open
Abstract
Bovine α-lactalbumin (αLA) has four disulfide (SS) bonds in the native form (N). On the oxidative folding pathways of this protein, two specific SS folding intermediates, i.e., (61–77, 73–91) and des[6–120], which have two and three native SS bonds, respectively, accumulate predominantly in the presence of Ca2+. In this study, we reinvestigated the pathways using a water-soluble cyclic selenoxide reagent, trans-3,4-dihydroxyselenolane oxide (DHSox), as a strong and quantitative oxidant to oxidize the fully reduced form (R). In the presence of ethylenediaminetetraacetic acid (EDTA) (under a metal-free condition), SS formation randomly proceeded, and N did not regenerate. On the other hand, two specific SS intermediates transiently generated in the presence of Ca2+. These intermediates could be assigned to (61–77, 73–91) and des[6–120] having two common SS bonds, i.e., Cys61-Cys77 and Cys73-Cys91, near the calcium binding pocket of the β-sheet domain. Much faster folding to N was observed in the presence of Mn2+, whereas Na+, K+, Mg2+, and Zn2+ did not affect the pathways. The two key intermediates were susceptible to temperature and a denaturant. The oxidative folding pathways revealed were significantly different from those of hen egg white lysozyme, which has the same SS-bonding pattern as αLA, suggesting that the folding pathways of SS-containing proteins can alter depending on the amino acid sequence and other factors, even when the SS-bond topologies are similar to each other.
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Affiliation(s)
- Reina Shinozaki
- Department of Chemistry, School of Science, Tokai University, Kitakaname, Hiratsuka-shi, Kanagawa 259-1292, Japan.
| | - Michio Iwaoka
- Department of Chemistry, School of Science, Tokai University, Kitakaname, Hiratsuka-shi, Kanagawa 259-1292, Japan.
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Lewney S, Smith LJ. Characterization of an alternative low energy fold for bovine α-lactalbumin formed by disulfide bond shuffling. Proteins 2011; 80:913-9. [PMID: 22189830 DOI: 10.1002/prot.23247] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Revised: 11/02/2011] [Accepted: 11/04/2011] [Indexed: 11/11/2022]
Abstract
Bovine α-lactalbumin (αLA) forms a misfolded disulfide bond shuffled isomer, X-αLA. This X-αLA isomer contains two native disulfide bridges (Cys 6-Cys 120 and Cys 28-Cys 111) and two non-native disulfide bridges (Cys 61-Cys 73 and Cys 77-Cys 91). MD simulations have been used to characterize the X-αLA isomer and its formation via disulfide bond shuffling and to compare it with the native fold of αLA. In the simulations of the X-αLA isomer the structure of the α-domain of native αLA is largely retained in agreement with experimental data. However, there are significant rearrangements in the β-domain, including the loss of the native β-sheet and calcium binding site. Interestingly, the energies of X-αLA and native αLA in simulations in the absence of calcium are closely similar. Thus, the X-αLA isomer represents a different low energy fold for the protein. Calcium binding to native αLA is shown to help preserve the structure of the β-domain of the protein limiting possibilities for disulfide bond shuffling. Hence, binding calcium plays an important role in both maintaining the native structure of αLA and providing a mechanism for distinguishing between folded and misfolded species.
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Affiliation(s)
- Sarah Lewney
- Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR, United Kingdom
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Hong DP, Xiong W, Chang JY, Jiang C. The role of the C-terminus of human α-synuclein: intra-disulfide bonds between the C-terminus and other regions stabilize non-fibrillar monomeric isomers. FEBS Lett 2011; 585:561-6. [PMID: 21237164 DOI: 10.1016/j.febslet.2011.01.009] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Accepted: 01/03/2011] [Indexed: 11/19/2022]
Abstract
Substantial evidence implicates that the aggregation of α-synuclein (αSyn) is a critical factor in the pathogenesis of Parkinson's disease. This study focuses on the role of αSyn C-terminus. We introduced two additional cysteine residues at positions 107 and 124 (A107C and A124C) to our previous construct. Five X-isomers of oxidative-folded mutation of α-synuclein with three disulfides were isolated and their secondary structures and aggregating features were analyzed. All isomers showed similar random coil structures as wild-type α-synuclein. However, these isomers did not form aggregates or fibrils, even with prolonged incubation, suggesting that the interactions between the C-terminal and N-terminal or central NAC region are important in maintaining the natively unfolded structure of αSyn and thus prevent αSyn from changing conformation, which is a critical step for fibrillation.
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Affiliation(s)
- Dong-Pyo Hong
- Research Center for Protein Chemistry, Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center, Houston, TX 77030, USA
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Jiang C, Xiong W, Lu BY, Gonda MA, Chang JY. Synthesis and Immune Response of Non-native Isomers of Vascular Endothelial Growth Factor. Biochemistry 2010; 49:6550-6. [DOI: 10.1021/bi100815n] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Chuantao Jiang
- Research Center for Protein Chemistry, Brown Foundation Institute of Molecular Medicine, and Department of Biochemistry and Molecular Biology, The University of Texas, Houston, Texas 77030
| | - Wei Xiong
- Research Center for Protein Chemistry, Brown Foundation Institute of Molecular Medicine, and Department of Biochemistry and Molecular Biology, The University of Texas, Houston, Texas 77030
| | - Bao-Yuan Lu
- Research Center for Protein Chemistry, Brown Foundation Institute of Molecular Medicine, and Department of Biochemistry and Molecular Biology, The University of Texas, Houston, Texas 77030
| | | | - Jui-Yoa Chang
- Research Center for Protein Chemistry, Brown Foundation Institute of Molecular Medicine, and Department of Biochemistry and Molecular Biology, The University of Texas, Houston, Texas 77030
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