1
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Tang Y, Zhang Y, Zhang D, Liu Y, Nussinov R, Zheng J. Exploring pathological link between antimicrobial and amyloid peptides. Chem Soc Rev 2024. [PMID: 39041297 DOI: 10.1039/d3cs00878a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/24/2024]
Abstract
Amyloid peptides (AMYs) and antimicrobial peptides (AMPs) are considered as the two distinct families of peptides, characterized by their unique sequences, structures, biological functions, and specific pathological targets. However, accumulating evidence has revealed intriguing pathological connections between these peptide families in the context of microbial infection and neurodegenerative diseases. Some AMYs and AMPs share certain structural and functional characteristics, including the ability to self-assemble, the presence of β-sheet-rich structures, and membrane-disrupting mechanisms. These shared features enable AMYs to possess antimicrobial activity and AMPs to acquire amyloidogenic properties. Despite limited studies on AMYs-AMPs systems, the cross-seeding phenomenon between AMYs and AMPs has emerged as a crucial factor in the bidirectional communication between the pathogenesis of neurodegenerative diseases and host defense against microbial infections. In this review, we examine recent developments in the potential interplay between AMYs and AMPs, as well as their pathological implications for both infectious and neurodegenerative diseases. By discussing the current progress and challenges in this emerging field, this account aims to inspire further research and investments to enhance our understanding of the intricate molecular crosstalk between AMYs and AMPs. This knowledge holds great promise for the development of innovative therapies to combat both microbial infections and neurodegenerative disorders.
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Affiliation(s)
- Yijing Tang
- Department of Chemical, Biomolecular, and Corrosion Engineering, The University of Akron, Ohio 44325, USA.
| | - Yanxian Zhang
- Division of Endocrinology and Diabetes, Department of Pediatrics, School of Medicine, Stanford University, Palo Alto, CA 94304, USA
| | - Dong Zhang
- The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia 30332, USA
| | - Yonglan Liu
- Cancer Innovation Laboratory, National Cancer Institute, Frederick, MD 21702, USA
| | - Ruth Nussinov
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA.
- Department of Human Molecular Genetics and Biochemistry Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Jie Zheng
- Department of Chemical, Biomolecular, and Corrosion Engineering, The University of Akron, Ohio 44325, USA.
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2
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Liang Y, Liu H, Jie Y, Liu M, He B, Wang J. Amyloid-like Aggregation of Wheat Gluten and Its Components during Cooking: Mechanisms and Structural Characterization. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:11080-11093. [PMID: 38690996 DOI: 10.1021/acs.jafc.3c09451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2024]
Abstract
Amyloid-like aggregation widely occurs during the processing and production of natural proteins, with evidence indicating its presence following the thermal processing of wheat gluten. However, significant gaps remain in understanding the underlying fibrillation mechanisms and structural polymorphisms. In this study, the amyloid-like aggregation behavior of wheat gluten and its components (glutenin and gliadin) during cooking was systematically analyzed through physicochemical assessment and structural characterization. The presence of amyloid-like fibrils (AFs) was confirmed using X-ray diffraction and Congo red staining, while Thioflavin T fluorescence revealed different patterns and rates of AFs growth among wheat gluten, glutenin, and gliadin. AFs in gliadin exhibited linear growth curves, while those in gluten and glutenin showed S-shaped curves, with the shortest lag phase and fastest growth rate (t1/2 = 2.11 min) observed in glutenin. Molecular weight analyses revealed AFs primarily in the 10-15 kDa range, shifting to higher weights over time. Glutenin-derived AFs had the smallest ζ-potential value (-19.5 mV) and the most significant size increase post cooking (approximately 400 nm). AFs in gluten involve interchain reorganization, hydrophobic interactions, and conformational transitions, leading to additional cross β-sheets. Atomic force microscopy depicted varying fibril structures during cooking, notably longer, taller, and stiffer AFs from glutenin.
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Affiliation(s)
- Ying Liang
- College of Biological Engineering, Henan University of Technology, Zhengzhou 450001, China
| | - Hao Liu
- College of Biological Engineering, Henan University of Technology, Zhengzhou 450001, China
| | - Yangyi Jie
- College of Biological Engineering, Henan University of Technology, Zhengzhou 450001, China
| | - Mei Liu
- College of Food Science and Engineering, Henan University of Technology, Zhengzhou 450001, China
| | - Baoshan He
- College of Food Science and Engineering, Henan University of Technology, Zhengzhou 450001, China
| | - Jinshui Wang
- College of Biological Engineering, Henan University of Technology, Zhengzhou 450001, China
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3
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Avni A, Joshi A, Mukhopadhyay S. Hydrogen-Deuterium Exchange Vibrational Raman Spectroscopy Distinguishes Distinct Amyloid Polymorphs Comprising Altered Core Architecture. J Phys Chem Lett 2023:5592-5601. [PMID: 37307286 DOI: 10.1021/acs.jpclett.3c01086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Amyloid fibrils are ordered protein aggregates comprising a hydrogen-bonded central cross-β core displaying a structural diversity in their supramolecular packing arrangements within the core. Such an altered packing results in amyloid polymorphism that gives rise to morphological and biological strain diversities. Here, we show that vibrational Raman spectroscopy coupled with hydrogen/deuterium (H/D) exchange discerns the key structural features that are responsible for yielding diverse amyloid polymorphs. Such a noninvasive and label-free methodology allows us to structurally distinguish distinct amyloid polymorphs displaying altered hydrogen bonding and supramolecular packing within the cross-β structural motif. By using quantitative molecular fingerprinting and multivariate statistical analysis, we analyze key Raman bands for the protein backbone and side chains that allow us to capture the conformational heterogeneity and structural distributions within distinct amyloid polymorphs. Our results delineate the key molecular factors governing the structural diversity in amyloid polymorphs and can potentially simplify studying amyloid remodeling by small molecules.
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4
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Liu H, Wang J, Liu M, Zhang X, Liang Y, Wang J. Effect of Thermal Treatment on the Self-Assembly of Wheat Gluten Polypeptide. MOLECULES (BASEL, SWITZERLAND) 2023; 28:molecules28020834. [PMID: 36677896 PMCID: PMC9862778 DOI: 10.3390/molecules28020834] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 12/30/2022] [Accepted: 01/12/2023] [Indexed: 01/17/2023]
Abstract
Self-assembled fibrillation of wheat gluten is a common phenomenon in the daily production and processing of wheat flour products. The driving forces for its formation and the factors that influence the morphology of fibrils have not been thoroughly investigated. In this study, the effect of three bonding changes (breaking hydrogen bonds, strengthening hydrophobic interactions, and SH-SS exchange reactions) on gluten polypeptide (GP) fibrillation was simulated by adjusting the heating temperature (room temperature (RT), 45 °C, 65 °C, and 95 °C). The results showed that the breakage of hydrogen bonds could induce conformational transitions in GPs and help to excite fibrillation in GPs. Strengthened hydrophobic interactions significantly contributed to the fibrillation of GPs. Covalent crosslinks generated by SH-SS exchange reactions might also promote the fibrillation of GPs. GPs with different degrees of hydrolysis (4.0%, 6.0%, and 10.0%, represented by DH 4, DH 6, and DH 10, respectively) presented different extents of fibrillation, with DH 10 GPs having a higher propensity to fibrillation than DH 4 and DH 6 GPs. The results of Fourier's transform infrared spectroscopy indicated that hydrophobic interactions drive the transition from a random coil and α-helix to a β-sheet. In addition, hydrophobic interactions also drive the intermolecular polymerization of GPs, resulting in larger molecular weight aggregates. The morphology presented by transmission electron microscopy showed that the greater the DH, the stronger the tendency for the worm-like aggregation of GPs.
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Affiliation(s)
- Hao Liu
- College of Biological Engineering, Henan University of Technology, Zhengzhou 450001, China
| | - Jingxuan Wang
- College of Biological Engineering, Henan University of Technology, Zhengzhou 450001, China
| | - Mei Liu
- College of Food Science and Engineering, Henan University of Technology, Zhengzhou 450001, China
| | - Xia Zhang
- College of Biological Engineering, Henan University of Technology, Zhengzhou 450001, China
| | - Ying Liang
- College of Biological Engineering, Henan University of Technology, Zhengzhou 450001, China
- Correspondence: (Y.L.); (J.W.); Tel./Fax: +86-0371-67756872 (Y.L.); +86-0371-67756512 (J.W.)
| | - Jinshui Wang
- College of Biological Engineering, Henan University of Technology, Zhengzhou 450001, China
- Correspondence: (Y.L.); (J.W.); Tel./Fax: +86-0371-67756872 (Y.L.); +86-0371-67756512 (J.W.)
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5
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Avni A, Joshi A, Walimbe A, Pattanashetty SG, Mukhopadhyay S. Single-droplet surface-enhanced Raman scattering decodes the molecular determinants of liquid-liquid phase separation. Nat Commun 2022; 13:4378. [PMID: 35902591 PMCID: PMC9334365 DOI: 10.1038/s41467-022-32143-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 07/19/2022] [Indexed: 11/09/2022] Open
Abstract
Biomolecular condensates formed via liquid-liquid phase separation (LLPS) are involved in a myriad of critical cellular functions and debilitating neurodegenerative diseases. Elucidating the role of intrinsic disorder and conformational heterogeneity of intrinsically disordered proteins/regions (IDPs/IDRs) in these phase-separated membrane-less organelles is crucial to understanding the mechanism of formation and regulation of biomolecular condensates. Here we introduce a unique single-droplet surface-enhanced Raman scattering (SERS) methodology that utilizes surface-engineered, plasmonic, metal nanoparticles to unveil the inner workings of mesoscopic liquid droplets of Fused in Sarcoma (FUS) in the absence and presence of RNA. These highly sensitive measurements offer unprecedented sensitivity to capture the crucial interactions, conformational heterogeneity, and structural distributions within the condensed phase in a droplet-by-droplet manner. Such an ultra-sensitive single-droplet vibrational methodology can serve as a potent tool to decipher the key molecular drivers of biological phase transitions of a wide range of biomolecular condensates involved in physiology and disease. The authors introduce a unique single-droplet surface-enhanced Raman scattering (SERS) methodology that illuminates a wealth of molecular information within the mesoscopic liquid condensed phase of Fused in Sarcoma in the absence and presence of RNA.
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Affiliation(s)
- Anamika Avni
- Centre for Protein Science, Design and Engineering, Indian Institute of Science Education and Research (IISER) Mohali, Punjab, India.,Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Punjab, India
| | - Ashish Joshi
- Centre for Protein Science, Design and Engineering, Indian Institute of Science Education and Research (IISER) Mohali, Punjab, India.,Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Punjab, India
| | - Anuja Walimbe
- Centre for Protein Science, Design and Engineering, Indian Institute of Science Education and Research (IISER) Mohali, Punjab, India.,Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Punjab, India
| | - Swastik G Pattanashetty
- Centre for Protein Science, Design and Engineering, Indian Institute of Science Education and Research (IISER) Mohali, Punjab, India.,Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Punjab, India
| | - Samrat Mukhopadhyay
- Centre for Protein Science, Design and Engineering, Indian Institute of Science Education and Research (IISER) Mohali, Punjab, India. .,Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Punjab, India. .,Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Punjab, India.
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6
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Spatiotemporal modulations in heterotypic condensates of prion and α-synuclein control phase transitions and amyloid conversion. Nat Commun 2022; 13:1154. [PMID: 35241680 PMCID: PMC8894376 DOI: 10.1038/s41467-022-28797-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 02/10/2022] [Indexed: 12/30/2022] Open
Abstract
Biomolecular condensation via liquid-liquid phase separation of proteins and nucleic acids is associated with a range of critical cellular functions and neurodegenerative diseases. Here, we demonstrate that complex coacervation of the prion protein and α-synuclein within narrow stoichiometry results in the formation of highly dynamic, reversible, thermo-responsive liquid droplets via domain-specific electrostatic interactions between the positively-charged intrinsically disordered N-terminal segment of prion and the acidic C-terminal tail of α-synuclein. The addition of RNA to these coacervates yields multiphasic, vesicle-like, hollow condensates. Picosecond time-resolved measurements revealed the presence of transient electrostatic nanoclusters that are stable on the nanosecond timescale and can undergo breaking-and-making of interactions on slower timescales giving rise to a liquid-like behavior in the mesoscopic regime. The liquid-to-solid transition drives a rapid conversion of complex coacervates into heterotypic amyloids. Our results suggest that synergistic prion-α-synuclein interactions within condensates provide mechanistic underpinnings of their physiological role and overlapping neuropathological features. The authors show that prion protein and α-synuclein undergo phase separation through domain-specific electrostatic interactions. These complex coacervates possess electrostatic nanoclusters and can convert into multiphasic condensates and amyloids.
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7
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Agarwal A, Rai SK, Avni A, Mukhopadhyay S. An intrinsically disordered pathological prion variant Y145Stop converts into self-seeding amyloids via liquid-liquid phase separation. Proc Natl Acad Sci U S A 2021; 118:e2100968118. [PMID: 34737230 PMCID: PMC8609423 DOI: 10.1073/pnas.2100968118] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/23/2021] [Indexed: 11/18/2022] Open
Abstract
Biomolecular condensation via liquid-liquid phase separation of intrinsically disordered proteins/regions (IDPs/IDRs) along with other biomolecules is proposed to control critical cellular functions, whereas aberrant phase transitions are associated with a range of neurodegenerative diseases. Here, we show that a disease-associated stop codon mutation of the prion protein (PrP) at tyrosine 145 (Y145Stop), resulting in a truncated, highly disordered, N-terminal IDR, spontaneously phase-separates into dynamic liquid-like droplets. Phase separation of this highly positively charged N-terminal segment is promoted by the electrostatic screening and a multitude of weak, transient, multivalent, intermolecular interactions. Single-droplet Raman measurements, in conjunction with an array of bioinformatic, spectroscopic, microscopic, and mutagenesis studies, revealed a highly mobile internal organization within the liquid-like condensates. The phase behavior of Y145Stop is modulated by RNA. Lower RNA:protein ratios promote condensation at a low micromolar protein concentration under physiological conditions. At higher concentrations of RNA, phase separation is abolished. Upon aging, these highly dynamic liquid-like droplets gradually transform into ordered, β-rich, amyloid-like aggregates. These aggregates formed via phase transitions display an autocatalytic self-templating characteristic involving the recruitment and binding-induced conformational conversion of monomeric Y145Stop into amyloid fibrils. In contrast to this intrinsically disordered truncated variant, the wild-type full-length PrP exhibits a much lower propensity for both condensation and maturation into amyloids, hinting at a possible protective role of the C-terminal domain. Such an interplay of molecular factors in modulating the protein phase behavior might have much broader implications in cell physiology and disease.
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Affiliation(s)
- Aishwarya Agarwal
- Centre for Protein Science, Design and Engineering, Indian Institute of Science Education and Research Mohali, Punjab 140306, India
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali 140306 Punjab, India
| | - Sandeep K Rai
- Centre for Protein Science, Design and Engineering, Indian Institute of Science Education and Research Mohali, Punjab 140306, India
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali 140306 Punjab, India
| | - Anamika Avni
- Centre for Protein Science, Design and Engineering, Indian Institute of Science Education and Research Mohali, Punjab 140306, India
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali 140306 Punjab, India
| | - Samrat Mukhopadhyay
- Centre for Protein Science, Design and Engineering, Indian Institute of Science Education and Research Mohali, Punjab 140306, India;
- Department of Biological Sciences, Indian Institute of Science Education and Research Mohali 140306 Punjab, India
- Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali 140306 Punjab, India
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8
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Mukhopadhyay S. The Dynamism of Intrinsically Disordered Proteins: Binding-Induced Folding, Amyloid Formation, and Phase Separation. J Phys Chem B 2020; 124:11541-11560. [PMID: 33108190 DOI: 10.1021/acs.jpcb.0c07598] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Intrinsically disordered proteins (IDPs) or natively unfolded proteins do not undergo autonomous folding into a well-defined 3-D structure and challenge the conventional structure-function paradigm. They are involved in a multitude of critical physiological functions by adopting various structural states via order-to-disorder transitions or by maintaining their disordered characteristics in functional complexes. In recent times, there has been a burgeoning interest in the investigation of intriguing behavior of IDPs using highly multidisciplinary and complementary approaches due to the pivotal role of this unique class of protein chameleons in physiology and disease. Over the past decade or so, our laboratory has been actively investigating the unique physicochemical properties of this class of highly dynamic, flexible, rapidly interconverting proteins. We have utilized a diverse array of existing and emerging tools involving steady-state and time-resolved fluorescence, Raman spectroscopy, circular dichroism, light scattering, fluorescence microscopy, and atomic force microscopy coupled with site-directed mutagenesis and other biochemical and biophysical tools to study a variety of interesting and important aspects of IDPs. In this Feature Article, I describe our work on the conformational characteristics, solvation dynamics, binding-induced folding, amyloid formation, and liquid-liquid phase separation of a number of amyloidogenic IDPs. A series of these studies described here captures the role of conformational plasticity and dynamics in directing binding, folding, assembly, aggregation, and phase transitions implicated in physiology and pathology.
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Affiliation(s)
- Samrat Mukhopadhyay
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences, and Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER), Mohali, India
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9
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Ke PC, Zhou R, Serpell LC, Riek R, Knowles TPJ, Lashuel HA, Gazit E, Hamley IW, Davis TP, Fändrich M, Otzen DE, Chapman MR, Dobson CM, Eisenberg DS, Mezzenga R. Half a century of amyloids: past, present and future. Chem Soc Rev 2020; 49:5473-5509. [PMID: 32632432 PMCID: PMC7445747 DOI: 10.1039/c9cs00199a] [Citation(s) in RCA: 301] [Impact Index Per Article: 75.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Amyloid diseases are global epidemics with profound health, social and economic implications and yet remain without a cure. This dire situation calls for research into the origin and pathological manifestations of amyloidosis to stimulate continued development of new therapeutics. In basic science and engineering, the cross-β architecture has been a constant thread underlying the structural characteristics of pathological and functional amyloids, and realizing that amyloid structures can be both pathological and functional in nature has fuelled innovations in artificial amyloids, whose use today ranges from water purification to 3D printing. At the conclusion of a half century since Eanes and Glenner's seminal study of amyloids in humans, this review commemorates the occasion by documenting the major milestones in amyloid research to date, from the perspectives of structural biology, biophysics, medicine, microbiology, engineering and nanotechnology. We also discuss new challenges and opportunities to drive this interdisciplinary field moving forward.
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Affiliation(s)
- Pu Chun Ke
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
- Zhongshan Hospital, Fudan University, 111 Yixueyuan Rd, Xuhui District, Shanghai, China
| | - Ruhong Zhou
- Institute of Quantitative Biology, Zhejiang University, Hangzhou 310058, China; Department of Chemistry, Columbia University, New York, New York, 10027, USA
| | - Louise C. Serpell
- School of Life Sciences, University of Sussex, Falmer, East Sussex BN1 9QG, UK
| | - Roland Riek
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Wolfgang-Pauli-Str. 10, 8093 Zurich, Switzerland
| | - Tuomas P. J. Knowles
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
- Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, CB3 0HE, Cambridge, UK
| | - Hilal A. Lashuel
- Laboratory of Molecular Neurobiology and Neuroproteomics, Brain Mind Institute, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Ehud Gazit
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences; Department of Materials Science and Engineering, Iby and Aladar Fleischman Faculty of Engineering, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Ian W. Hamley
- School of Chemistry, Food Biosciences and Pharmacy, University of Reading, Whiteknights, Reading RG6 6AD, UK
| | - Thomas P. Davis
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane Qld 4072, Australia
| | - Marcus Fändrich
- Institute of Protein Biochemistry, Ulm University, 89081, Ulm, Germany
| | - Daniel Erik Otzen
- Department of Molecular Biology, Center for Insoluble Protein Structures (inSPIN), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark
| | - Matthew R. Chapman
- Department of Molecular, Cellular and Developmental Biology, Centre for Microbial Research, University of Michigan, Ann Arbor, MI 48109-1048, USA
| | - Christopher M. Dobson
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - David S. Eisenberg
- Departments of Chemistry and Biochemistry and Biological Chemistry, UCLA-DOE Institute and Howard Hughes Medical Institute, UCLA, Los Angeles, CA, USA
| | - Raffaele Mezzenga
- Department of Health Science & Technology, ETH Zurich, Schmelzbergstrasse 9, LFO, E23, 8092 Zurich, Switzerland
- Department of Materials, ETH Zurich, Wolfgang Pauli Strasse 10, 8093 Zurich, Switzerland
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10
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Monge-Morera M, Lambrecht MA, Deleu LJ, Gallardo R, Louros NN, De Vleeschouwer M, Rousseau F, Schymkowitz J, Delcour JA. Processing Induced Changes in Food Proteins: Amyloid Formation during Boiling of Hen Egg White. Biomacromolecules 2020; 21:2218-2228. [PMID: 32202759 DOI: 10.1021/acs.biomac.0c00186] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Amyloid fibrils (AFs) are highly ordered protein nanofibers composed of cross β-structure that occur in nature, but that also accumulate in age-related diseases. Amyloid propensity is a generic property of proteins revealed by conditions that destabilize the native state, suggesting that food processing conditions may promote AF formation. This had only been shown for foie gras, but not in common foodstuffs. We here extracted a dense network of fibrillar proteins from commonly consumed boiled hen egg white (EW) using chemical and/or enzymatic treatments. Conversion of EW proteins into AFs during boiling was demonstrated by thioflavin T fluorescence, Congo red staining, and X-ray fiber diffraction measurements. Our data show that cooking converts approximately 1-3% of the protein in EW into AFs, suggesting that they are a common component of the human diet.
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Affiliation(s)
- Margarita Monge-Morera
- KU Leuven, Laboratory of Food Chemistry and Biochemistry and Leuven Food Science and Nutrition Research Centre (LFoRCe), Kasteelpark Arenberg 20, B-3001 Leuven, Belgium
| | - Marlies A Lambrecht
- KU Leuven, Laboratory of Food Chemistry and Biochemistry and Leuven Food Science and Nutrition Research Centre (LFoRCe), Kasteelpark Arenberg 20, B-3001 Leuven, Belgium
| | - Lomme J Deleu
- KU Leuven, Laboratory of Food Chemistry and Biochemistry and Leuven Food Science and Nutrition Research Centre (LFoRCe), Kasteelpark Arenberg 20, B-3001 Leuven, Belgium
| | - Rodrigo Gallardo
- KU Leuven, Switch Laboratory, Department of Cellular and Molecular Medicine, Herestraat 49, B-3001 Leuven, Belgium.,University of Leeds, Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Garstang Building, LS2 9JT Leeds, United Kingdom
| | - Nikolaos N Louros
- KU Leuven, Switch Laboratory, Department of Cellular and Molecular Medicine, Herestraat 49, B-3001 Leuven, Belgium
| | - Matthias De Vleeschouwer
- KU Leuven, Switch Laboratory, Department of Cellular and Molecular Medicine, Herestraat 49, B-3001 Leuven, Belgium
| | - Frederic Rousseau
- KU Leuven, Switch Laboratory, Department of Cellular and Molecular Medicine, Herestraat 49, B-3001 Leuven, Belgium
| | - Joost Schymkowitz
- KU Leuven, Switch Laboratory, Department of Cellular and Molecular Medicine, Herestraat 49, B-3001 Leuven, Belgium
| | - Jan A Delcour
- KU Leuven, Laboratory of Food Chemistry and Biochemistry and Leuven Food Science and Nutrition Research Centre (LFoRCe), Kasteelpark Arenberg 20, B-3001 Leuven, Belgium
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11
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Milošević J, Petrić J, Jovčić B, Janković B, Polović N. Exploring the potential of infrared spectroscopy in qualitative and quantitative monitoring of ovalbumin amyloid fibrillation. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2020; 229:117882. [PMID: 31818644 DOI: 10.1016/j.saa.2019.117882] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 11/29/2019] [Accepted: 11/30/2019] [Indexed: 06/10/2023]
Abstract
Amyloid fibrils are highly ordered self-assembled (poly)peptide aggregates with cross-β structural pattern. Ovalbumin was used as a model for exploring the potential of infrared spectroscopy in detecting structural transitions and quantitative monitoring of amyloid fibrillation. Low pH (pH 2) and high temperature (90 °C) over the course of 24 h were conditions applied for amyloid formation. Fibrillation of ovalbumin was monitored by ThT and ANS fluorescence, and SDS PAGE. A significant increase in ThT fluorescence with a plateau reached after 4 h of incubation, without the lag phase, was detected. Structural transitions leading to amyloid fibrillation were analysed using all three Amide regions in ATR-FTIR spectra. Significant changes were detected in Amide I and Amide III region (decrease of α-helix and increase of β-sheet peaks). To establish a fast, precise and simple method for quantitative monitoring of amyloid fibrillation, the Amide I/Amide II ratios of aggregation specific β-sheets (1625 and 1695 cm-1, respectively) with 1540 cm-1 as internal standard were used, resulting in good correlation (R2 = 0.93 and 0.95) with the data observed by monitoring ThT fluorescence. On the other hand, assessing aggregation specific β-sheet contents by self-deconvolution showed lower correlation with ThT fluorescence (R2 = 0.75 and 0.64). Here we examined structural transitions during ovalbumin fibrillation in a qualitative and quantitative manner by exploiting the full potential of Amide regions simultaneously. Secondary structure distribution was monitored using second derivative spectra in Amide I region. A novel, simple mathematical calculation for quantitative monitoring of fibrils formation was presented employing that the increase in low and high frequency aggregation specific β-sheet in Amide I region compared to the internal standard in Amide II region is suitable for fibril formation monitoring.
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Affiliation(s)
- Jelica Milošević
- University of Belgrade - Faculty of Chemistry, Department of Biochemistry, Belgrade, Serbia
| | - Jovan Petrić
- University of Belgrade - Faculty of Chemistry, Department of Biochemistry, Belgrade, Serbia
| | - Branko Jovčić
- University of Belgrade - Faculty of Biology, Belgrade, Serbia; Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Belgrade, Serbia
| | - Brankica Janković
- University of Belgrade - Faculty of Chemistry, Department of Biochemistry, Belgrade, Serbia
| | - Natalija Polović
- University of Belgrade - Faculty of Chemistry, Department of Biochemistry, Belgrade, Serbia.
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12
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Choi H, Lee W, Lee G, Yoon DS, Na S. The Formation Mechanism of Segmented Ring-Shaped Aβ Oligomers and Protofibrils. ACS Chem Neurosci 2019; 10:3830-3838. [PMID: 31313912 DOI: 10.1021/acschemneuro.9b00324] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
A clear understanding of amyloid formation with diverse morphologies is critical to overcoming the fatal disease amyloidosis. Studies have revealed that monomer concentration is a crucial factor for determining amyloid morphologies, such as protofibrils, annular, or spherical oligomers. However, gaining a complete understanding of the mechanism of formation of the various amyloid morphologies has been limited by the lack of experimental devices and insufficient knowledge. In this study, we demonstrate that the monomer concentration is an essential factor in determining the morphology of beta-amyloid (Aβ) oligomers or protofibrils. By computational and experimental approaches, we investigated the strategies for structural stabilization of amyloid protein, the morphological changes, and amyloid aggregation. In particular, we found unprecedented conformations, e.g., single bent oligomers and segmented ring-shaped protofibrils, the formation of which was explained by the computational analysis. Our findings provide insight into the structural features of amyloid molecules formed at low concentrations of monomer, which will help determine the clinical targets (in therapy) to effectively inhibit amyloid formation in the early stages of the amyloid growth phase.
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Affiliation(s)
| | - Wonseok Lee
- Department of Control and Instrumentation Engineering , Korea University , Sejong 30019 , Republic of Korea
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13
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Jansens KJA, Lambrecht MA, Rombouts I, Monge Morera M, Brijs K, Rousseau F, Schymkowitz J, Delcour JA. Conditions Governing Food Protein Amyloid Fibril Formation-Part I: Egg and Cereal Proteins. Compr Rev Food Sci Food Saf 2019; 18:1256-1276. [PMID: 33336994 DOI: 10.1111/1541-4337.12462] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 04/26/2019] [Accepted: 05/13/2019] [Indexed: 12/18/2022]
Abstract
Conditions including heating mode, time, temperature, pH, moisture and protein concentration, shear, and the presence of alcohols, chaotropic/reducing agents, enzymes, and/or salt influence amyloid fibril (AF) formation as they can affect the accessibility of amino acid sequences prone to aggregate. As some conditions applied on model protein resemble conditions in food processing unit operations, we here hypothesize that food processing can lead to formation of protein AFs with a compact cross β-sheet structure. This paper reviews conditions and food constituents that affect amyloid fibrillation of egg and cereal proteins. While egg and cereal proteins often coexist in food products, their impact on each other's fibrillation remains unknown. Hen egg ovalbumin and lysozyme form AFs when subjected to moderate heating at acidic pH separately. AFs can also be formed at higher pH, especially in the presence of alcohols or chaotropic/reducing agents. Tryptic wheat gluten digests can form fibrillar structures at neutral pH and maize and rice proteins do so in aqueous ethanol or at acidic pH, respectively.
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Affiliation(s)
- Koen J A Jansens
- KU Leuven, Laboratory of Food Chemistry and Biochemistry and Leuven Food Science and Nutrition Research Centre (LFoRCe), Kasteelpark Arenberg 20, B-3001, Leuven, Belgium.,Nutrex NV, Achterstenhoek 5, B-2275, Lille, Belgium
| | - Marlies A Lambrecht
- KU Leuven, Laboratory of Food Chemistry and Biochemistry and Leuven Food Science and Nutrition Research Centre (LFoRCe), Kasteelpark Arenberg 20, B-3001, Leuven, Belgium
| | - Ine Rombouts
- KU Leuven, Laboratory of Food Chemistry and Biochemistry and Leuven Food Science and Nutrition Research Centre (LFoRCe), Kasteelpark Arenberg 20, B-3001, Leuven, Belgium.,KU Leuven, ECOVO, Kasteelpark Arenberg 21, B-3001, Leuven, Belgium
| | - Margarita Monge Morera
- KU Leuven, Laboratory of Food Chemistry and Biochemistry and Leuven Food Science and Nutrition Research Centre (LFoRCe), Kasteelpark Arenberg 20, B-3001, Leuven, Belgium
| | - Kristof Brijs
- KU Leuven, Laboratory of Food Chemistry and Biochemistry and Leuven Food Science and Nutrition Research Centre (LFoRCe), Kasteelpark Arenberg 20, B-3001, Leuven, Belgium
| | - Frederic Rousseau
- Switch Laboratory, VIB, and Dept. of Cellular and Molecular Medicine, KU Leuven, B-3000, Leuven, Belgium
| | - Joost Schymkowitz
- Switch Laboratory, VIB, and Dept. of Cellular and Molecular Medicine, KU Leuven, B-3000, Leuven, Belgium
| | - Jan A Delcour
- KU Leuven, Laboratory of Food Chemistry and Biochemistry and Leuven Food Science and Nutrition Research Centre (LFoRCe), Kasteelpark Arenberg 20, B-3001, Leuven, Belgium
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14
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Yousaf M, Ahmad M, Bhatti IA, Nasir A, Hasan M, Jian X, Kalantar-Zadeh K, Mahmood N. In Vivo and In Vitro Monitoring of Amyloid Aggregation via BSA@FGQDs Multimodal Probe. ACS Sens 2019; 4:200-210. [PMID: 30596230 DOI: 10.1021/acssensors.8b01216] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Early detection of peptide aggregate intermediates is quite challenging because of their variable and complex nature as well as due to lack of reliable sensors for diagnosis. Herein, we report the detection of monomers and oligomers using specified fluorescence and a magnetic resonance imaging (MRI) multimodal probe based on bovine-serum-albumin-capped fluorine functionalized graphene quantum dots (BSA@FGQDs). This probe enables in vitro fluorescence-based monitoring of human islet amyloid polypeptide (hIAPP), insulin, and amyloid β(1-42) (Aβ42) monomers and oligomers during the fibrillogenesis dynamic. Up to 90% fluorescence quenching of BSA@FGQDs probe upon addition of amyloid monomers/oligomers was observed due to static quenching and nonradiative energy transfer. Moreover, the BSA@FGQDs probe shows 10 times higher signals in detecting amyloid intermediates and fibrils than that of conventional thioflavin dye. A negative Δ G° value (-36.21 kJ/mol) indicates spontaneous interaction of probe with the peptide. These interactions are hydrogen bonding and hydrophobic as proved by thermodynamic parameters. Visual binding clues of BSA@FGQDs with different morphological states of amyloid protein was achieved through electron microscopy. Furthermore, intravenous and intracranial injection of BSA@FGQDs probe in Alzheimer model mice brain enabled in vivo detection of amyloid plaques in live mice brain by 19F MRI through contrast enhancement. Our proposed probe not only effectively monitors in vitro fibrillation kinetics of number of amyloid proteins with higher sensitivity and specificity than thioflavin dye, but also, the presence of a 19F center makes BSA@FGQDs an effective probe as a noninvasive and nonradiative in vivo detection probe for amyloid plaques.
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Affiliation(s)
- Maryam Yousaf
- Department of Chemistry, University of Agriculture Faisalabad, Faisalabad 38040, Pakistan
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, P. R. China
| | - Muhammad Ahmad
- Department of Structure and Environmental Engineering, University of Agriculture Faisalabad, Faisalabad 38040, Pakistan
| | - Ijaz Ahmad Bhatti
- Department of Chemistry, University of Agriculture Faisalabad, Faisalabad 38040, Pakistan
| | - Abdul Nasir
- Department of Structure and Environmental Engineering, University of Agriculture Faisalabad, Faisalabad 38040, Pakistan
| | - Murtaza Hasan
- Department of Biochemistry & Biotechnology (Baghdad-ul-Jadeed Campus), The Islamia University of Bahawalpur, Bahawalpur 63100, Pakistan
| | - Xian Jian
- School of Materials and Energy, National Engineering Research Centre of Electromagnetic Radiation Control Materials, Centre for Applied Chemistry, University of Electronic Science and Technology, Chengdu 611731, P.R. China
| | - Kourosh Kalantar-Zadeh
- School of Chemical Engineering, University of New South Wales (UNSW), 2052 Kensington, New South Wales, Australia
| | - Nasir Mahmood
- School of Engineering, RMIT University, 3001 Melbourne, Victoria, Australia
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15
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Ghosh DK, Roy A, Ranjan A. Aggregation-prone Regions in HYPK Help It to Form Sequestration Complex for Toxic Protein Aggregates. J Mol Biol 2018; 430:963-986. [DOI: 10.1016/j.jmb.2018.02.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 02/09/2018] [Accepted: 02/10/2018] [Indexed: 11/24/2022]
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16
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Detergent-induced aggregation of an amyloidogenic intrinsically disordered protein. J CHEM SCI 2017. [DOI: 10.1007/s12039-017-1386-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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17
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Swasthi HM, Mukhopadhyay S. Electrostatic lipid-protein interactions sequester the curli amyloid fold on the lipopolysaccharide membrane surface. J Biol Chem 2017; 292:19861-19872. [PMID: 29021250 DOI: 10.1074/jbc.m117.815522] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 10/04/2017] [Indexed: 12/14/2022] Open
Abstract
Curli is a functional amyloid protein in the extracellular matrix of enteric Gram-negative bacteria. Curli is assembled at the cell surface and consists of CsgA, the major subunit of curli, and a membrane-associated nucleator protein, CsgB. Oligomeric intermediates that accumulate during the lag phase of amyloidogenesis are generally toxic, but the underlying mechanism by which bacterial cells overcome this toxicity during curli assembly at the surface remains elusive. Here, we elucidated the mechanism of curli amyloidogenesis and provide molecular insights into the strategy by which bacteria can potentially bypass the detrimental consequences of toxic amyloid intermediates. Using a diverse range of biochemical and biophysical tools involving circular dichroism, fluorescence, Raman spectroscopy, and atomic force microscopy imaging, we characterized the molecular basis of the interaction of CsgB with a membrane-mimetic anionic surfactant as well as with lipopolysaccharide (LPS) constituting the outer leaflet of Gram-negative bacteria. Aggregation studies revealed that the electrostatic interaction of the positively charged C-terminal region of the protein with a negatively charged head group of surfactant/LPS promotes a protein-protein interaction that results in facile amyloid formation without a detectable lag phase. We also show that CsgB, in the presence of surfactant/LPS, accelerates the fibrillation rate of CsgA by circumventing the lag phase during nucleation. Our findings suggest that the electrostatic interactions between lipid and protein molecules play a pivotal role in efficiently sequestering the amyloid fold of curli on the membrane surface without significant accumulation of toxic oligomeric intermediates.
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Affiliation(s)
- Hema M Swasthi
- From the Centre for Protein Science, Design and Engineering.,Chemical Sciences, Indian Institute of Science Education and Research (IISER), Mohali, Sector 81, Knowledge City, Mohali, Punjab, India
| | - Samrat Mukhopadhyay
- From the Centre for Protein Science, Design and Engineering, .,Chemical Sciences, Indian Institute of Science Education and Research (IISER), Mohali, Sector 81, Knowledge City, Mohali, Punjab, India.,Departments of Biological Sciences and
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18
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Narang D, Singh A, Swasthi HM, Mukhopadhyay S. Characterization of Salt-Induced Oligomerization of Human β2-Microglobulin at Low pH. J Phys Chem B 2016; 120:7815-23. [PMID: 27467899 DOI: 10.1021/acs.jpcb.6b05619] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Misfolding and amyloid aggregation of human β2-microglobulin (β2m) have been linked to dialysis-related amyloidosis. Previous studies have shown that in the presence of different salt concentrations and at pH 2.5, β2m assembles into aggregates with distinct morphologies. However, the structural and mechanistic details of the aggregation of β2m, giving rise to different morphologies, are poorly understood. In this work, we have extensively characterized the salt-induced oligomers of the acid-unfolded state of β2m using an array of biophysical tools including steady-state and time-resolved fluorescence, circular dichroism, dynamic light scattering, and atomic force microscopy imaging. Fluorescence studies using the oligomer-sensitive molecular rotor, 4-(dicyanovinyl)-julolidine, in conjunction with the light scattering and cross-linking assay indicated that at low salt (NaCl) concentrations β2m exists as a disordered monomer, capable of transforming into ordered amyloid. In the presence of higher concentrations of salt, β2m aggregates into a larger oligomeric species that does not appear to transform into amyloid fibrils. Site-specific fluorescence experiments using single Trp variants of β2m revealed that the middle region of the protein is incorporated into these oligomers, whereas the C-terminal segment is highly exposed to bulk water. Additionally, stopped-flow kinetic experiments indicated that the formation of hydrophobic core and oligomerization occur concomitantly. Our results revealed the distinct pathways by which β2m assembles into oligomers and fibrils.
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Affiliation(s)
- Dominic Narang
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences and ‡Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) , Mohali, Knowledge City, Sector 81, S.A.S. Nagar, Mohali 140306, Punjab, India
| | - Anubhuti Singh
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences and ‡Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) , Mohali, Knowledge City, Sector 81, S.A.S. Nagar, Mohali 140306, Punjab, India
| | - Hema M Swasthi
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences and ‡Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) , Mohali, Knowledge City, Sector 81, S.A.S. Nagar, Mohali 140306, Punjab, India
| | - Samrat Mukhopadhyay
- Centre for Protein Science, Design and Engineering, Department of Biological Sciences and ‡Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) , Mohali, Knowledge City, Sector 81, S.A.S. Nagar, Mohali 140306, Punjab, India
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19
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Joshi PN, Purushottam L, Das NK, Mukherjee S, Rai V. Protein self-assembly induces promiscuous nucleophilic biocatalysis in Morita–Baylis–Hillman (MBH) reaction. RSC Adv 2016. [DOI: 10.1039/c5ra23949d] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Self-assembled states of proteins render efficient promiscuous nucleophilic biocatalysis in MBH reaction in a green process.
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Affiliation(s)
- Pralhad N. Joshi
- Department of Chemistry
- Indian Institute of Science Education and Research (IISER) Bhopal
- Bhopal
- India
| | - Landa Purushottam
- Department of Chemistry
- Indian Institute of Science Education and Research (IISER) Bhopal
- Bhopal
- India
| | - Nirmal K. Das
- Department of Chemistry
- Indian Institute of Science Education and Research (IISER) Bhopal
- Bhopal
- India
| | - Saptarshi Mukherjee
- Department of Chemistry
- Indian Institute of Science Education and Research (IISER) Bhopal
- Bhopal
- India
| | - Vishal Rai
- Department of Chemistry
- Indian Institute of Science Education and Research (IISER) Bhopal
- Bhopal
- India
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20
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Conformational Switching and Nanoscale Assembly of Human Prion Protein into Polymorphic Amyloids via Structurally Labile Oligomers. Biochemistry 2015; 54:7505-13. [DOI: 10.1021/acs.biochem.5b01110] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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21
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Arya S, Kumari A, Dalal V, Bhattacharya M, Mukhopadhyay S. Appearance of annular ring-like intermediates during amyloid fibril formation from human serum albumin. Phys Chem Chem Phys 2015; 17:22862-71. [PMID: 26264974 DOI: 10.1039/c5cp03782d] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The self-assembly of proteins triggered by a conformational switch into highly ordered β-sheet rich amyloid fibrils has captivated burgeoning interest in recent years due to the involvement of amyloids in a variety of human diseases and a diverse range of biological functions. Here, we have investigated the mechanism of fibrillogenesis of human serum albumin (HSA), an all-α-helical protein, using an array of biophysical tools that include steady-state as well as time-resolved fluorescence, circular dichroism and Raman spectroscopy in conjunction with atomic force microscopy (AFM). Investigations into the temporal evolution of nanoscale morphology using AFM revealed the presence of ring-like intermediates that subsequently transformed into worm-like fibrils presumably by a ring-opening mechanism. Additionally, a multitude of morphologically-diverse oligomers were observed on the pathway to amyloid formation. Kinetic analysis using multiple structural probes in-tandem indicated that HSA amyloid assembly is a concerted process encompassing a major structural change that is primarily mediated by hydrophobic interactions between thermally-induced disordered segments originating in various domains. A slower growth kinetics of aggregates suggested that the protein structural reorganization is a prerequisite for fibril formation. Moreover, time-dependent Raman spectroscopic studies of HSA aggregation provided key molecular insights into the conformational transitions occurring within the protein amide backbone and at the residue-specific level. Our data revealed the emergence of conformationally-diverse disulfides as a consequence of structural reorganization and sequestration of tyrosines into the hydrophobic amyloid core comprising antiparallel cross β-sheets.
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Affiliation(s)
- Shruti Arya
- Centre for Protein Science Design and Engineering, Indian Institute of Science Education and Research (IISER), Mohali 140306, Punjab, India.
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