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Juković M, Ratkaj I, Kalafatovic D, Bradshaw NJ. Amyloids, amorphous aggregates and assemblies of peptides - Assessing aggregation. Biophys Chem 2024; 308:107202. [PMID: 38382283 DOI: 10.1016/j.bpc.2024.107202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 01/31/2024] [Accepted: 02/14/2024] [Indexed: 02/23/2024]
Abstract
Amyloid and amorphous aggregates represent the two major categories of aggregates associated with diseases, and although exhibiting distinct features, researchers often treat them as equivalent, which demonstrates the need for more thorough characterization. Here, we compare amyloid and amorphous aggregates based on their biochemical properties, kinetics, and morphological features. To further decipher this issue, we propose the use of peptide self-assemblies as minimalistic models for understanding the aggregation process. Peptide building blocks are significantly smaller than proteins that participate in aggregation, however, they make a plausible means to bridge the gap in discerning the aggregation process at the more complex, protein level. Additionally, we explore the potential use of peptide-inspired models to research the liquid-liquid phase separation as a feasible mechanism preceding amyloid formation. Connecting these concepts can help clarify our understanding of aggregation-related disorders and potentially provide novel drug targets to impede and reverse these serious illnesses.
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Affiliation(s)
- Maja Juković
- Faculty of Biotechnology and Drug Development, University of Rijeka, 51000 Rijeka, Croatia
| | - Ivana Ratkaj
- Faculty of Biotechnology and Drug Development, University of Rijeka, 51000 Rijeka, Croatia
| | - Daniela Kalafatovic
- Faculty of Biotechnology and Drug Development, University of Rijeka, 51000 Rijeka, Croatia.
| | - Nicholas J Bradshaw
- Faculty of Biotechnology and Drug Development, University of Rijeka, 51000 Rijeka, Croatia.
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2
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Majid N, Khan RH. Protein aggregation: Consequences, mechanism, characterization and inhibitory strategies. Int J Biol Macromol 2023; 242:125123. [PMID: 37270122 DOI: 10.1016/j.ijbiomac.2023.125123] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 05/01/2023] [Accepted: 05/25/2023] [Indexed: 06/05/2023]
Abstract
Proteins play a major role in the regulation of various cellular functions including the synthesis of structural components. But proteins are stable under physiological conditions only. A slight variation in environmental conditions can cost them huge in terms of conformational stability ultimately leading to aggregation. Under normal conditions, aggregated proteins are degraded or removed from the cell by a quality control system including ubiquitin-proteasomal machinery and autophagy. But they are burdened under diseased conditions or are impaired by the aggregated proteins leading to the generation of toxicity. The misfolding and aggregation of protein such as amyloid-β, α-synuclein, human lysozyme etc., are responsible for certain diseases including Alzheimer, Parkinson, and non- neuropathic systemic amyloidosis respectively. Extensive research has been done to find the therapeutics for such diseases but till now we have got only symptomatic treatment that will reduce the disease severity but will not target the initial formation of nucleus responsible for disease progression and propagation. Hence there is an urgent need to develop the drugs targeting the cause of the disease. For this, a wide knowledge related to misfolding and aggregation under the same heading is required as described in this review alongwith the strategies hypothesized and implemented till now. This will contribute a lot to the work of researchers in the field of neuroscience.
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Affiliation(s)
- Nabeela Majid
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh 202002, India
| | - Rizwan Hasan Khan
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh 202002, India.
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3
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Kumari K, Sharma GS, Gupta A, Singh KS, Singh LR. Functionally active cross-linked protein oligomers formed by homocysteine thiolactone. Sci Rep 2023; 13:5620. [PMID: 37024663 PMCID: PMC10079695 DOI: 10.1038/s41598-023-32694-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 03/31/2023] [Indexed: 04/08/2023] Open
Abstract
Deposition of high-order protein oligomers is a common hallmark of a large number of human diseases and therefore, has been of immense medical interest. From the past several decades, efforts are being made to characterize protein oligomers and explore how they are linked with the disease pathologies. In general, oligomers are non-functional, rather cytotoxic in nature while the functional (non-cytotoxic) oligomers are quite rare. In the present study, we identified new protein oligomers of Ribonuclease-A and Lysozyme that contain functionally active fractions. These functional oligomers are disulfide cross-linked, native-like, and obtained as a result of the covalent modification of the proteins by the toxic metabolite, homocysteine thiolactone accumulated under hyperhomocysteinemia (a condition responsible for cardiovascular complications including atherosclerosis). These results have been obtained from the extensive analysis of the nature of oligomers, functional status, and structural integrity of the proteins using orthogonal techniques. The study implicates the existence of such oligomers as protein sinks that may sequester toxic homocysteines in humans.
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Affiliation(s)
- Kritika Kumari
- Dr. B. R. Ambedkar Center for Biomedical Research, University of Delhi, Delhi, 110007, India
| | - Gurumayum Suraj Sharma
- Department of Botany, Bhaskaracharya College of Applied Sciences, University of Delhi, New Delhi, 110075, India
| | - Akshita Gupta
- Dr. B. R. Ambedkar Center for Biomedical Research, University of Delhi, Delhi, 110007, India
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4
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Khan JM, Malik A, Alresaini SM. Molecular mechanism of insulin aggregation in the presence of a cationic surfactant. Int J Biol Macromol 2023; 230:123370. [PMID: 36693606 DOI: 10.1016/j.ijbiomac.2023.123370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 01/16/2023] [Accepted: 01/17/2023] [Indexed: 01/22/2023]
Abstract
Protein aggregation and amyloid fibrillation are connected with neurodegenerative disorders. Insulin, a small molecular weight protein related to type II diabetes, has been shown to self-assemble to form protein aggregates. In this work, we investigated the effects of cetyltrimethylammonium bromide (CTAB) of insulin on the in vitro aggregation process at pH 7.4 and 2.0. The aggregation tendency of insulin was measured using a variety of biophysical approaches, including turbidity measurements, light scattering, far UV-CD, ThT dye binding, and transmission electron microscopy. The turbidity results demonstrated that at pH 7.4, a low concentration of CTAB (30-180 μM) causes insulin aggregation but at higer concentration (>180 μM) aggregation was not seen. However, at pH 2.0, both low as well as high concentrations of CTAB were unable to promote insulin aggregation. The ThT dye binding and far-UV CD data suggest that aggregation induced by CTAB is not having an ordered structure. Insulin treated with higher concentrations (>180 μM) of CTAB, the insulin gained a secondary structure. The possible cause of inducing aggregation in insulin is electrostatic and hydrophobic interaction because insulin contains a net negative charge at pH 7.4 and no aggregation at pH 2.0 due to electrostatic repulsion.
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Affiliation(s)
- Javed Masood Khan
- Department of Food Science and Nutrition, College of Food and Agricultural Sciences, King Saud University, 2460, Riyadh 11451, Saudi Arabia.
| | - Ajamaluddin Malik
- Department of Biochemistry, College of Science, King Saud University, Riyadh, Saudi Arabia
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5
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Feng H, Zhao Q, Zhang B, Hu H, Liu M, Wu K, Li X, Zhang X, Zhang L, Liu Y. Enabling Photo-Crosslinking and Photo-Sensitizing Properties for Synthetic Fluorescent Protein Chromophores. Angew Chem Int Ed Engl 2023; 62:e202215215. [PMID: 36370037 DOI: 10.1002/anie.202215215] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Indexed: 11/13/2022]
Abstract
Synthetic fluorescent protein chromophores have been reported for their singlet state fluorescence properties and applications in bioimaging, but rarely for the triplet state chemistries. Herein, we enabled their photo-sensitizing and photo-crosslinking properties through rational modulations. Extension of molecular conjugation and introduction of heavy atoms promoted the generation of reactive oxygen species. Unlike other photosensitizers, these chromophores selectively photo-crosslinked aggregated proteins and uncovered the interactome profiles. We also exemplified their general applications in chromophore-assisted light inactivation, photodynamic therapy and photo induced polymerization. Theoretical calculation, pathway analysis and transient absorption spectroscopy provided mechanistic insights for this triplet state chemistry. Overall, this work expands the function and application of synthetic fluorescent protein chromophores by enabling their triplet excited state properties.
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Affiliation(s)
- Huan Feng
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, 116023, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qun Zhao
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, 116023, China
| | - Beirong Zhang
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, 116023, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Hang Hu
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Meng Liu
- University of Chinese Academy of Sciences, Beijing, 100049, China.,State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, 116023, China
| | - Kaifeng Wu
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, 116023, China
| | - Xiaosong Li
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Xin Zhang
- Department of Chemistry and Westlake Laboratory of Life Sciences and Biomedicine, Westlake University, 18 Shilongshan Road, Hangzhou, 310024, China
| | - Lihua Zhang
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, 116023, China
| | - Yu Liu
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, 116023, China
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Golam Kibria M, Akazawa-Ogawa Y, Hagihara Y, Kuroda Y. Immune response with long-term memory triggered by amorphous aggregates of misfolded anti-EGFR V HH-7D12 is directed against the native V HH-7D12 as well as the framework of the analogous V HH-9G8. Eur J Pharm Biopharm 2021; 165:13-21. [PMID: 33971271 DOI: 10.1016/j.ejpb.2021.05.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 04/29/2021] [Accepted: 05/03/2021] [Indexed: 02/06/2023]
Abstract
We previously demonstrated that amorphous aggregates of misfolded VHH-7D12 antibodies (VHH-Mis), a potential anti-EGFR drug, can generate a robust serum IgG response. Here we investigate the immunogenic nature, especially the specificity of the immune response induced by VHH-Mis. To this end, we used two natively folded and 77% identical anti-EGFR VHHs (VHH-7D12 and VHH-9G8) that possess a common framework but distinct complementarity determining regions (CDRs). In 60% of mice immunized with VHH-Mis, the anti-VHH-7D12 IgG titer was stronger than the anti-VHH-9G8 titer (Group-1). In the remaining mice (40%; Group-2), the anti-VHH-7D12 and anti-VHH-9G8 titer were almost identical. We rationalized these results by hypothesizing that mice in Group-1 produced IgG mostly against the VHH-7D12's CDRs, whereas in Group-2 mice, they targeted the VHH's framework. The IgG specificity against VHH-7D12 and VHH-9G8 was essentially unchanged over 17 weeks in both groups. Further, in all mice (Group-1&2) re-immunized with native VHH-7D12, the IgG titer against VHH-7D12 increased sharply but not against VHH-9G8. On the other hand, none of the three Group-1 mice re-immunized with native VHH-9G8 showed immunogenicity against VHH-7D12 nor VHH-9G8. Whereas, in Group-2 mice (three/three) re-immunized with VHH-9G8, the IgG titers against both VHHs increased but slowly. Flow-cytometric studies showed that VHH-Mis immunized mice generated a higher number of effector and central memory T-cells. Overall, these observations indicate that amorphous aggregates made of a misfolded VHH can induce serum IgG against its natively folded self and analogous VHHs having a similar framework but distinct CDRs. Furthermore, a robust long-term immune response with memory was established against its natively folded self but with a nil-to-moderate immune response against natively folded VHH analogs.
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Affiliation(s)
- Md Golam Kibria
- Department of Biotechnology and Life Science, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakamachi, Koganei-shi, Tokyo 184-8588, Japan
| | - Yoko Akazawa-Ogawa
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31, Midorigaoka, Ikeda, Osaka 563-8577, Japan
| | - Yoshihisa Hagihara
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31, Midorigaoka, Ikeda, Osaka 563-8577, Japan
| | - Yutaka Kuroda
- Department of Biotechnology and Life Science, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakamachi, Koganei-shi, Tokyo 184-8588, Japan.
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7
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Nakamura S, Kibria MG, Unzai S, Kuroda Y, Kidokoro SI. Reversible Oligomerization and Reverse Hydrophobic Effect Induced by Isoleucine Tags Attached at the C-Terminus of a Simplified BPTI Variant. Biochemistry 2020; 59:3660-3668. [PMID: 32924442 DOI: 10.1021/acs.biochem.0c00436] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Protein amorphous aggregation has become the focus of great attention, as it can impair the ability of cells to function properly. Here, we evaluated the effects of three peptide tags, consisting of one, three, and five consecutive isoleucines attached at the C-terminus end of a simplified bovine pancreatic trypsin inhibitor (BPTI) variant, BPTI-19A, on the thermal stability and oligomerization by circular dichroism spectrometry and differential scanning calorimetry in detail. All of the BPTI-19A variants exhibited a reversible and apparently two-state thermal transition like BPTI-19A at pH 4.7. The thermal transition of the five-isoleucine-tagged variant showed clear protein-concentration dependence, where the apparent denaturation temperature decreased as the protein concentration increased. Quantitative analysis indicated that this phenomenon originated from the presence of reversibly oligomerized (RO) states at high temperatures. The results also illustrated that the thermodynamic stability difference between the native and the monomeric denatured state in all the proteins was destabilized by the hydrophobic tags and was well explained by the reverse hydrophobic effect due to the tags. The existence of the RO states was confirmed by both analytical ultracentrifugation and dynamic light scattering. This indicated that the five-isoleucine hydrophobic tag is strong enough to induce intermolecular hydrophobic contact among the denatured molecules leading to oligomerization, and even one- or three-isoleucine tags are effective enough to generate intramolecular hydrophobic contact, thus provoking denaturation through the reverse hydrophobic effect.
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Affiliation(s)
- Shigeyoshi Nakamura
- Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan.,Department of General Education, National Institute of Technology, Ube College, 2-14-1 Tokiwadai, Ube, Yamaguchi 755-8555, Japan
| | - Md Golam Kibria
- Department of Biotechnology and Life Science, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-15 Nakamachi, Koganei, Tokyo 184-8588, Japan
| | - Satoru Unzai
- Department of Frontier Bioscience, Faculty of Bioscience and Applied Chemistry, Hosei University, 3-7-2 Kajino-cho, Koganei, Tokyo 184-8584, Japan
| | - Yutaka Kuroda
- Department of Biotechnology and Life Science, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-15 Nakamachi, Koganei, Tokyo 184-8588, Japan
| | - Shun-Ichi Kidokoro
- Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan
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Rahman N, Islam MM, Kibria MG, Unzai S, Kuroda Y. A systematic mutational analysis identifies a 5-residue proline tag that enhances the in vivo immunogenicity of a non-immunogenic model protein. FEBS Open Bio 2020; 10:1947-1956. [PMID: 33017095 PMCID: PMC7530378 DOI: 10.1002/2211-5463.12941] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 07/01/2020] [Accepted: 07/23/2020] [Indexed: 12/24/2022] Open
Abstract
Poor immunogenicity of small proteins is a major hurdle in developing vaccines or producing antibodies for biopharmaceutical usage. Here, we systematically analyzed the effects of 10 solubility controlling peptide tags (SCP‐tags) on the immunogenicity of a non‐immunogenic model protein, bovine pancreatic trypsin inhibitor (BPTI‐19A; 6 kDa). CD, fluorescence, DLS, SLS, and AUC measurements indicated that the SCP‐tags did not change the secondary structure content nor the tertiary structures of the protein nor its monomeric state. ELISA results indicated that the 5‐proline (C5P) and 5‐arginine (C5R) tags unexpectedly increased the IgG level of BPTI‐19A by 240‐ and 73‐fold, respectively, suggesting that non‐oligomerizing SCP‐tags may provide a novel method for increasing the immunogenicity of a protein in a highly specific manner.
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Affiliation(s)
- Nafsoon Rahman
- Department of Biotechnology and Life Sciences, Graduate School of Engineering, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Mohammad Monirul Islam
- Department of Biochemistry and Molecular Biology, University of Chittagong, Chittagong, Bangladesh
| | - Md Golam Kibria
- Department of Biotechnology and Life Sciences, Graduate School of Engineering, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Satoru Unzai
- Department of Frontier Bioscience, Faculty of Bioscience and Applied Chemistry, Hosei University, Tokyo, Japan
| | - Yutaka Kuroda
- Department of Biotechnology and Life Sciences, Graduate School of Engineering, Tokyo University of Agriculture and Technology, Tokyo, Japan
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Falke S, Brognaro H, Martirosyan A, Dierks K, Betzel C. A multi-channel in situ light scattering instrument utilized for monitoring protein aggregation and liquid dense cluster formation. Heliyon 2019; 5:e03016. [PMID: 31886430 PMCID: PMC6921120 DOI: 10.1016/j.heliyon.2019.e03016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 11/29/2019] [Accepted: 12/06/2019] [Indexed: 12/18/2022] Open
Abstract
Liquid-liquid phase separation (LLPS) phenomena have been observed in vitro as well as in vivo and came in focus of interdisciplinary research activities particularly aiming at understanding the physico-chemical pathways of LLPS and its functionality in recent years. Dynamic light scattering (DLS) has been proven to be a most efficient method to analyze macromolecular clustering in solutions and suspensions with diverse applications in life sciences, material science and biotechnology. For spatially and time-resolved investigations of LLPS, i.e. formation of liquid dense protein clusters (LDCs) and aggregation, a novel eight-channel in situ DLS instrument was designed, constructed and applied. The real time formation of LDCs of glucose isomerase (GI) and bovine pancreatic trypsin inhibitor (BPTI) under different physico-chemical conditions was investigated in situ. Complex shifts in the particle size distributions indicated growth of LDCs up to the μm size regime. Additionally, near-UV circular dichroism spectroscopy was performed to monitor the folding state of the proteins in the process of LDC formation.
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Affiliation(s)
- Sven Falke
- University Hamburg, Institute of Biochemistry and Molecular Biology, Laboratory for Structural Biology of Infection and Inflammation, c/o DESY, Build. 22a, Notkestr. 85, 22607, Hamburg, Germany
- The Hamburg Center for Ultrafast Imaging, c/o DESY, Luruper Chaussee 149, Hamburg, 22607, Germany
| | - Hévila Brognaro
- University Hamburg, Institute of Biochemistry and Molecular Biology, Laboratory for Structural Biology of Infection and Inflammation, c/o DESY, Build. 22a, Notkestr. 85, 22607, Hamburg, Germany
- Centre for Free-Electron-Laser Science, c/o DESY, Luruper Chaussee 149, Hamburg, 22607, Germany
| | - Arayik Martirosyan
- University Hamburg, Institute of Biochemistry and Molecular Biology, Laboratory for Structural Biology of Infection and Inflammation, c/o DESY, Build. 22a, Notkestr. 85, 22607, Hamburg, Germany
| | - Karsten Dierks
- Xtal Concepts GmbH, Schnackenburgallee 13, 22525, Hamburg, Germany
| | - Christian Betzel
- University Hamburg, Institute of Biochemistry and Molecular Biology, Laboratory for Structural Biology of Infection and Inflammation, c/o DESY, Build. 22a, Notkestr. 85, 22607, Hamburg, Germany
- The Hamburg Center for Ultrafast Imaging, c/o DESY, Luruper Chaussee 149, Hamburg, 22607, Germany
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10
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Large-scale all-atom molecular dynamics alanine-scanning of IAPP octapeptides provides insights into the molecular determinants of amyloidogenicity. Sci Rep 2019; 9:2530. [PMID: 30792475 PMCID: PMC6384915 DOI: 10.1038/s41598-018-38401-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 12/11/2018] [Indexed: 12/11/2022] Open
Abstract
In order to investigate the early phase of the amyloid formation by the short amyloidogenic octapeptide sequence (‘NFGAILSS’) derived from IAPP, we carried out a 100ns all-atom molecular dynamics (MD) simulations of systems that contain 27 peptides and over 30,000 water molecules. The large-scale calculations were performed for the wild type sequence and seven alanine-scanned sequences using AMBER 8.0 on RIKEN’s special purpose MD-GRAPE3 supercomputer, using the all-atom point charge force field ff99, which do not favor β-structures. Large peptide clusters (size 18–26 mers) were observed for all simulations, and our calculations indicated that isoleucine at position 5 played important role in the formation of β-rich clusters. In the oligomeric state, the wild type and the S7A sequences had the highest β-structure content (~14%), as calculated by DSSP, in line with experimental observations, whereas I5A and G3A had the highest helical content (~20%). Importantly, the β-structure preferences of wild type IAPP originate from its association into clusters and are not intrinsic to its sequence. Altogether, the results of this first large-scale, multi-peptide all-atom molecular dynamics simulation appear to provide insights into the mechanism of amyloidogenic and non-amyloidogenic oligomers that mainly corroborate previous experimental observations.
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Kabir MG, Islam MM, Kuroda Y. Reversible association of proteins into sub-visible amorphous aggregates using short solubility controlling peptide tags. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1866:366-372. [PMID: 28951312 DOI: 10.1016/j.bbapap.2017.09.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Revised: 09/01/2017] [Accepted: 09/21/2017] [Indexed: 01/04/2023]
Abstract
Careful analysis of sub-visible amorphous aggregates, where proteins associate non-covalently in either native or denatured states without forming a specific quaternary structure, may shed insight into the mechanisms of protein aggregation and solubility. Here we report a biophysical and biochemical analysis of our model protein, a bovine pancreatic trypsin inhibitor variant (BPTI-19A), whose oligomerization were controlled by attaching solubility controlling peptide tags (SCP tags) to its C terminus, which are short peptides composed of a single type of amino acid that modulate protein solubility. The dynamic light scattering and static light scattering at 25°C indicated that 11 out of 15 SCP tags merely affected the hydrodynamic radius and light scattering intensity of our reference variants BPTI-19A and BPTI-C2G. On the other hand, hydrophobic SCP tags composed of 5 Ile (C5I) or 5 Leu (C5L) were associated into sub-visible aggregates. Circular dichroism indicated that all tagged BPTI variants had the same secondary structure contents as the reference BPTI-19A at 25°C, suggesting that BPTI-C5I and C5L kept their native structure upon association. Furthermore, the thermal denaturation of all of the BPTI variants was fully reversible and typical of natively folded small globular proteins, as monitored by CD at 222 nm. However, the thermal stability of BPTI-19A tagged with hydrophobic residues decreased with increasing protein concentration and tag's hydrophobicity, and BPTI-C5I and C5L were partially denatured at 37°C. Biochemical stability assessed by limited proteolysis with pepsin correlated with the extent of the variants' aggregation, and the large sub-visible aggregates formed by BPTI-C5I and C5L significantly increased their resistance to pepsin proteolysis. Altogether, these observations indicated that hydrophobic SCP tags led to the reversible association of native-like proteins into sub-visible soluble amorphous aggregates resistant to pepsin digestion.
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Affiliation(s)
- Md Golam Kabir
- Department of Biotechnology and Life Sciences, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakamachi, Koganei-shi, Tokyo 184-8588, Japan
| | - Mohammad Monirul Islam
- Department of Biochemistry and Molecular Biology, University of Chittagong, Chittagong 4331, Bangladesh
| | - Yutaka Kuroda
- Department of Biotechnology and Life Sciences, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakamachi, Koganei-shi, Tokyo 184-8588, Japan.
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Yuan B, Sun Y, Guo Q, Huang J, Yang X, Chen Y, Wen X, Meng X, Liu J, Wang K. High Signal-to-Background Ratio Detection of Cancer Cells with Activatable Strategy Based on Target-Induced Self-Assembly of Split Aptamers. Anal Chem 2017; 89:9347-9353. [PMID: 28782924 DOI: 10.1021/acs.analchem.7b02153] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Highly sensitive detection of cancer cells with high signal-to-background ratio (SBR) is still urgently needed. Here, a self-assembling activatable probe (SAAP) based on split aptamers was developed to meet this purpose. The SAAP is formed with quenched fluorescence; only when target cells are present would the split aptamers self-assemble together and thus activate fluorescence by intramolecular and intermolecular fluorescence quenching strategies. As proof of concept, a split aptamer pair stemming from an intact aptamer, ZY11, developed by our lab was selected to construct SAAP. Owing to the design of self-assembly and activation strategy, the SBR of our approach could be raised to ∼40 and achieved a very low detection limit of seven target 7721 cells in 100 μL of binding buffer. Meanwhile, one-step detection of target cells was achieved within 15 min without any washing steps and pretreatment, which shows potential for point-of-care detection. Moreover, we succeeded in the specific recognition of target cells in 50% human serum and mixed cell samples, which indicated this strategy had great advantages in detection in complex biological samples. In addition, dual-signal detection was also successfully implemented, which may be helpful for accurate detection of target cells. Therefore, this rapid, facile, specific, and highly sensitive detection method for cancer cells may provide convenience in cancer research and medical diagnosis.
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Affiliation(s)
- Baoyin Yuan
- State Key Laboratory of Chemo/Biosensing and Chemometrics and Key Laboratory for Bio-Nanotechnology and Molecular Engineering of Hunan Province, College of Chemistry and Chemical Engineering, Hunan University , Changsha 410082, China
| | - Yuqiong Sun
- State Key Laboratory of Chemo/Biosensing and Chemometrics and Key Laboratory for Bio-Nanotechnology and Molecular Engineering of Hunan Province, College of Chemistry and Chemical Engineering, Hunan University , Changsha 410082, China
| | - Qiuping Guo
- State Key Laboratory of Chemo/Biosensing and Chemometrics and Key Laboratory for Bio-Nanotechnology and Molecular Engineering of Hunan Province, College of Chemistry and Chemical Engineering, Hunan University , Changsha 410082, China
| | - Jin Huang
- State Key Laboratory of Chemo/Biosensing and Chemometrics and Key Laboratory for Bio-Nanotechnology and Molecular Engineering of Hunan Province, College of Chemistry and Chemical Engineering, Hunan University , Changsha 410082, China
| | - Xiaohai Yang
- State Key Laboratory of Chemo/Biosensing and Chemometrics and Key Laboratory for Bio-Nanotechnology and Molecular Engineering of Hunan Province, College of Chemistry and Chemical Engineering, Hunan University , Changsha 410082, China
| | - Yuanyuan Chen
- State Key Laboratory of Chemo/Biosensing and Chemometrics and Key Laboratory for Bio-Nanotechnology and Molecular Engineering of Hunan Province, College of Chemistry and Chemical Engineering, Hunan University , Changsha 410082, China
| | - Xiaohong Wen
- State Key Laboratory of Chemo/Biosensing and Chemometrics and Key Laboratory for Bio-Nanotechnology and Molecular Engineering of Hunan Province, College of Chemistry and Chemical Engineering, Hunan University , Changsha 410082, China
| | - Xiangxian Meng
- State Key Laboratory of Chemo/Biosensing and Chemometrics and Key Laboratory for Bio-Nanotechnology and Molecular Engineering of Hunan Province, College of Chemistry and Chemical Engineering, Hunan University , Changsha 410082, China
| | - Jianbo Liu
- State Key Laboratory of Chemo/Biosensing and Chemometrics and Key Laboratory for Bio-Nanotechnology and Molecular Engineering of Hunan Province, College of Chemistry and Chemical Engineering, Hunan University , Changsha 410082, China
| | - Kemin Wang
- State Key Laboratory of Chemo/Biosensing and Chemometrics and Key Laboratory for Bio-Nanotechnology and Molecular Engineering of Hunan Province, College of Chemistry and Chemical Engineering, Hunan University , Changsha 410082, China
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