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Bennett AL, Cranford KN, Bates AL, Sabatini CR, Lee HS. A molecular dynamics study of cell-penetrating peptide transportan-10 (TP10): Binding, folding and insertion to transmembrane state in zwitterionic membrane. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2024; 1866:184218. [PMID: 37634858 PMCID: PMC10843101 DOI: 10.1016/j.bbamem.2023.184218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 08/05/2023] [Accepted: 08/23/2023] [Indexed: 08/29/2023]
Abstract
Transportan 10 (TP10) is a 21-residue, cationic, α-helical cell-penetrating peptide that can be used as a delivery vector for various bioactive molecules. Based on recent confocal microscopy studies, it is believed that TP10 can translocate across neutral lipid membrane passively, possibly as a monomer, without the formation of permanent pore. Here, we performed extensive molecular dynamics (MD) simulations of TP10W (Y3W variant of TP10) to find the microscopic details of binding, folding and insertion of TP10W to transmembrane state in POPC bilayer. Binding study with CHARMM36 force field showed that TP10W initially binds to the membrane surface in unstructured configuration, but it spontaneously folds into α-helical conformation under the lipid head groups. Further insertion of TP10W, changing from a surface bound state to a vertically oriented transmembrane state, was investigated via umbrella simulations. The resulting free energy profile shows a relatively small barrier between two states, suggesting a possible translocation pathway as a monomer. In fact, unbiased simulation of transmembrane TP10W revealed how a charged Lys side chain can move from one leaflet to the other without a significant free energy cost. Finally, we compared the results of TP10W simulations with those of point mutated variants (TP10W-K12A18 and TP10W-K19L) to understand the effect of charge distribution on the peptide. It was observed that such a conservative mutation can cause noticeable changes in the conformations of both surface bound and transmembrane states. The results of present study will be discussed in relation to the experimentally observed activities of TP10W against neutral membrane.
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Affiliation(s)
- Ashley L Bennett
- Department of Chemistry and Biochemistry, University of North Carolina, Wilmington, NC 28403, United States of America
| | - Kristen N Cranford
- Department of Chemistry and Biochemistry, University of North Carolina, Wilmington, NC 28403, United States of America
| | - Austin L Bates
- Department of Chemistry and Biochemistry, University of North Carolina, Wilmington, NC 28403, United States of America
| | - Christopher R Sabatini
- Department of Chemistry and Biochemistry, University of North Carolina, Wilmington, NC 28403, United States of America
| | - Hee-Seung Lee
- Department of Chemistry and Biochemistry, University of North Carolina, Wilmington, NC 28403, United States of America.
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2
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Siposova K, Petrenko VI, Garcarova I, Sedlakova D, Almásy L, Kyzyma OA, Kriechbaum M, Musatov A. The intriguing dose-dependent effect of selected amphiphilic compounds on insulin amyloid aggregation: Focus on a cholesterol-based detergent, Chobimalt. Front Mol Biosci 2022; 9:955282. [PMID: 36060240 PMCID: PMC9437268 DOI: 10.3389/fmolb.2022.955282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 07/22/2022] [Indexed: 11/15/2022] Open
Abstract
The amyloidogenic self-assembly of many peptides and proteins largely depends on external conditions. Among amyloid-prone proteins, insulin attracts attention because of its physiological and therapeutic importance. In the present work, the amyloid aggregation of insulin is studied in the presence of cholesterol-based detergent, Chobimalt. The strategy to elucidate the Chobimalt-induced effect on insulin fibrillogenesis is based on performing the concentration- and time-dependent analysis using a combination of different experimental techniques, such as ThT fluorescence assay, CD, AFM, SANS, and SAXS. While at the lowest Chobimalt concentration (0.1 µM; insulin to Chobimalt molar ratio of 1:0.004) the formation of insulin fibrils was not affected, the gradual increase of Chobimalt concentration (up to 100 µM; molar ratio of 1:4) led to a significant increase in ThT fluorescence, and the maximal ThT fluorescence was 3-4-fold higher than the control insulin fibril’s ThT fluorescence intensity. Kinetic studies confirm the dose-dependent experimental results. Depending on the concentration of Chobimalt, either (i) no effect is observed, or (ii) significantly, ∼10-times prolonged lag-phases accompanied by the substantial, ∼ 3-fold higher relative ThT fluorescence intensities at the steady-state phase are recorded. In addition, at certain concentrations of Chobimalt, changes in the elongation-phase are noticed. An increase in the Chobimalt concentrations also triggers the formation of insulin fibrils with sharply altered morphological appearance. The fibrils appear to be more flexible and wavy-like with a tendency to form circles. SANS and SAXS data also revealed the morphology changes of amyloid fibrils in the presence of Chobimalt. Amyloid aggregation requires the formation of unfolded intermediates, which subsequently generate amyloidogenic nuclei. We hypothesize that the different morphology of the formed insulin fibrils is the result of the gradual binding of Chobimalt to different binding sites on unfolded insulin. A similar explanation and the existence of such binding sites with different binding energies was shown previously for the nonionic detergent. Thus, the data also emphasize the importance of a protein partially-unfolded state which undergoes the process of fibrils formation; i.e., certain experimental conditions or the presence of additives may dramatically change not only kinetics but also the morphology of fibrillar aggregates.
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Affiliation(s)
- Katarina Siposova
- Department of Biophysics, Institute of Experimental Physics, Slovak Academy of Sciences, Kosice, Slovakia
- *Correspondence: Katarina Siposova, ; Andrey Musatov,
| | - Viktor I. Petrenko
- BCMaterials—Basque Center for Materials, Applications and Nanostructures, Leioa, Spain
- Ikerbasque, Basque Foundation for Science, Bilbao, Spain
| | - Ivana Garcarova
- Department of Biophysics, Institute of Experimental Physics, Slovak Academy of Sciences, Kosice, Slovakia
| | - Dagmar Sedlakova
- Department of Biophysics, Institute of Experimental Physics, Slovak Academy of Sciences, Kosice, Slovakia
| | - László Almásy
- Neutron Spectroscopy Department, Centre for Energy Research, Budapest, Hungary
| | - Olena A. Kyzyma
- Department of Biophysics, Institute of Experimental Physics, Slovak Academy of Sciences, Kosice, Slovakia
- Faculty of Physics, Taras Shevchenko National University of Kyiv, Kyiv, Ukraine
| | - Manfred Kriechbaum
- Institute of Inorganic Chemistry, Graz University of Technology, Graz, Austria
| | - Andrey Musatov
- Department of Biophysics, Institute of Experimental Physics, Slovak Academy of Sciences, Kosice, Slovakia
- *Correspondence: Katarina Siposova, ; Andrey Musatov,
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Wongsirojkul N, Masuta A, Shimokawa N, Takagi M. Control of Line Tension at Phase-Separated Lipid Domain Boundaries: Monounsaturated Fatty Acids with Different Chain Lengths and Osmotic Pressure. MEMBRANES 2022; 12:membranes12080781. [PMID: 36005696 PMCID: PMC9415386 DOI: 10.3390/membranes12080781] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Revised: 08/04/2022] [Accepted: 08/12/2022] [Indexed: 06/01/2023]
Abstract
Line tension at phase-separated lipid domain boundaries is an important factor that governs the stability of the phase separation. We studied the control of the line tension in lipid membranes composed of dioleoylphosphocholine (DOPC), dipalmitoylphosphocholine (DPPC), and cholesterol (Chol) by the addition of the following three monounsaturated fatty acids (MUFAs) with different chain lengths: palmitoleic acid (PaA), oleic acid (OA), and eicosenoic acid (EiA). In addition, we attempted to alter the line tension by applying osmotic pressure. The phase behavior of the MUFA-containing lipid membranes in the presence and absence of osmotic stress was observed by fluorescence and confocal laser scanning microscopy. The line tension was quantitatively measured from the domain boundary fluctuation by flicker spectroscopy, and the interactions between the lipids and MUFAs were examined by differential scanning calorimetry. PaA and OA, which are shorter MUFAs, decreased the line tension, whereas EiA changed the liquid domain to a solid domain. The osmotic pressure increased the line tension, even in the presence of MUFAs. It may be possible to control the line tension by combining the chemical approach of MUFA addition and the physical approach of applying osmotic pressure.
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Affiliation(s)
| | | | | | - Masahiro Takagi
- Correspondence: (N.S.); (M.T.); Tel.: +81-761-51-1650 (M.T.)
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Das A, Shah M, Saraogi I. Molecular Aspects of Insulin Aggregation and Various Therapeutic Interventions. ACS BIO & MED CHEM AU 2022; 2:205-221. [PMID: 37101572 PMCID: PMC10114644 DOI: 10.1021/acsbiomedchemau.1c00054] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
Protein aggregation leading to the formation of amyloid fibrils has various adverse effects on human health ranging from fatigue and numbness to organ failure and death in extreme cases. Insulin, a peptide hormone commonly used to treat diabetes, undergoes aggregation at the site of repeated injections in diabetic patients as well as during its industrial production and transport. The reduced bioavailability of insulin due to aggregation hinders the proper control of glucose levels in diabetic patients. Thus, it is necessary to develop rational approaches for inhibiting insulin aggregation, which in turn requires a detailed understanding of the mechanism of fibrillation. Given the relative simplicity of insulin and ease of access, insulin has also served as a model system for studying amyloids. Approaches to inhibit insulin aggregation have included the use of natural molecules, synthetic peptides or small molecules, and bacterial chaperone machinery. This review focuses on insulin aggregation with an emphasis on its mechanism, the structural features of insulin fibrils, and the reported inhibitors that act at different stages in the aggregation pathway. We discuss molecules that can serve as leads for improved inhibitors for use in commercial insulin formulations. We also discuss the aggregation propensity of fast- and slow-acting insulin biosimilars, commonly administered to diabetic patients. The development of better insulin aggregation inhibitors and insights into their mechanism of action will not only aid diabetic therapies, but also enhance our knowledge of protein amyloidosis.
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Affiliation(s)
- Anirban Das
- Department
of Chemistry and Department of Biological Sciences, Indian
Institute of Science Education and Research
Bhopal, Bhopal Bypass Road, Bhauri, Bhopal 462066, Madhya Pradesh, India
| | - Mosami Shah
- Department
of Chemistry and Department of Biological Sciences, Indian
Institute of Science Education and Research
Bhopal, Bhopal Bypass Road, Bhauri, Bhopal 462066, Madhya Pradesh, India
| | - Ishu Saraogi
- Department
of Chemistry and Department of Biological Sciences, Indian
Institute of Science Education and Research
Bhopal, Bhopal Bypass Road, Bhauri, Bhopal 462066, Madhya Pradesh, India
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Khemtemourian L, Fatafta H, Davion B, Lecomte S, Castano S, Strodel B. Structural Dissection of the First Events Following Membrane Binding of the Islet Amyloid Polypeptide. Front Mol Biosci 2022; 9:849979. [PMID: 35372496 PMCID: PMC8965455 DOI: 10.3389/fmolb.2022.849979] [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: 01/06/2022] [Accepted: 02/18/2022] [Indexed: 11/13/2022] Open
Abstract
The islet amyloid polypeptide (IAPP) is the main constituent of the amyloid fibrils found in the pancreas of type 2 diabetes patients. The aggregation of IAPP is known to cause cell death, where the cell membrane plays a dual role: being a catalyst of IAPP aggregation and being the target of IAPP toxicity. Using ATR-FTIR spectroscopy, transmission electron microscopy, and molecular dynamics simulations we investigate the very first molecular steps following IAPP binding to a lipid membrane. In particular, we assess the combined effects of the charge state of amino-acid residue 18 and the IAPP-membrane interactions on the structures of monomeric and aggregated IAPP. Distinct IAPP-membrane interaction modes for the various IAPP variants are revealed. Membrane binding causes IAPP to fold into an amphipathic α-helix, which in the case of H18K-, and H18R-IAPP readily moves beyond the headgroup region. For all IAPP variants but H18E-IAPP, the membrane-bound helix is an intermediate on the way to amyloid aggregation, while H18E-IAPP remains in a stable helical conformation. The fibrillar aggregates of wild-type IAPP and H18K-IAPP are dominated by an antiparallel β-sheet conformation, while H18R- and H18A-IAPP exhibit both antiparallel and parallel β-sheets as well as amorphous aggregates. Our results emphasize the decisive role of residue 18 for the structure and membrane interaction of IAPP. This residue is thus a good therapeutic target for destabilizing membrane-bound IAPP fibrils to inhibit their toxic actions.
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Affiliation(s)
- Lucie Khemtemourian
- Université de Bordeaux, CNRS, Bordeaux IMP, CBMN, Pessac, France
- *Correspondence: Lucie Khemtemourian, ; Birgit Strodel,
| | - Hebah Fatafta
- Institute of Biological Information Processing, Structural Biochemistry, Jülich, Germany
- JuStruct, Jülich Center for Structural Biology, Jülich, Germany
| | - Benoit Davion
- Université de Bordeaux, CNRS, Bordeaux IMP, CBMN, Pessac, France
| | - Sophie Lecomte
- Université de Bordeaux, CNRS, Bordeaux IMP, CBMN, Pessac, France
| | - Sabine Castano
- Université de Bordeaux, CNRS, Bordeaux IMP, CBMN, Pessac, France
| | - Birgit Strodel
- Institute of Biological Information Processing, Structural Biochemistry, Jülich, Germany
- JuStruct, Jülich Center for Structural Biology, Jülich, Germany
- Institute of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- *Correspondence: Lucie Khemtemourian, ; Birgit Strodel,
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Molecular Mechanisms of Amylin Turnover, Misfolding and Toxicity in the Pancreas. Molecules 2022; 27:molecules27031021. [PMID: 35164285 PMCID: PMC8838401 DOI: 10.3390/molecules27031021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 01/24/2022] [Accepted: 01/29/2022] [Indexed: 12/13/2022] Open
Abstract
Amyloidosis is a common pathological event in which proteins self-assemble into misfolded soluble and insoluble molecular forms, oligomers and fibrils that are often toxic to cells. Notably, aggregation-prone human islet amyloid polypeptide (hIAPP), or amylin, is a pancreatic hormone linked to islet β-cells demise in diabetics. The unifying mechanism by which amyloid proteins, including hIAPP, aggregate and kill cells is still matter of debate. The pathology of type-2 diabetes mellitus (T2DM) is characterized by extracellular and intracellular accumulation of toxic hIAPP species, soluble oligomers and insoluble fibrils in pancreatic human islets, eventually leading to loss of β-cell mass. This review focuses on molecular, biochemical and cell-biology studies exploring molecular mechanisms of hIAPP synthesis, trafficking and degradation in the pancreas. In addition to hIAPP turnover, the dynamics and the mechanisms of IAPP–membrane interactions; hIAPP aggregation and toxicity in vitro and in situ; and the regulatory role of diabetic factors, such as lipids and cholesterol, in these processes are also discussed.
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Gupta A, Dey S, Bhowmik D, Maiti S. Coexisting Ordered and Disordered Membrane Phases Have Distinct Modes of Interaction with Disease-Associated Oligomers. J Phys Chem B 2022; 126:1016-1023. [PMID: 35104126 DOI: 10.1021/acs.jpcb.1c09421] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ordered membrane domains are thought to influence the attachment and insertion of toxic amyloid oligomers, and consequently, their toxicity. However, if and how the molecular aspects of this interaction depend on the membrane order is poorly understood. Here we measure the affinity, location, and degree of insertion of the small oligomers of hIAPP (human Islet Amyloid Polypeptide, associated with Type II diabetes) at near-physiological concentrations to adjacent domains of a biphasic lipid bilayer. Using simultaneous atomic force, confocal and fluorescence lifetime microscopy (AFM-FLIM), we find that hIAPP oligomers have a nearly 8-fold higher affinity to the disordered domains over the ordered domains. To probe whether this difference indicates different modes of interaction, we measure the change of lifetime of peptide-attached fluorescent labels induced by soluble fluorescence quenchers and also measure the kinetics of localized photobleaching. We find that in the raft-like ordered domains, the oligomers primarily lie on the aqueous interface with limited membrane penetration. However, in the neighboring disordered domains, their C-termini penetrate deeper into the lipid bilayer. We conclude that local membrane order determines not only the affinity but also the mode of interaction of amyloid oligomers, which may have significant implications for disease mechanisms.
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Affiliation(s)
- Ankur Gupta
- Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
| | - Simli Dey
- Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
| | - Debanjan Bhowmik
- Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
| | - Sudipta Maiti
- Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
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