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Yousefi A, Ying C, Parmenter CD, Assadipapari M, Sanderson G, Zheng Z, Xu L, Zargarbashi S, Hickman GJ, Cousins RB, Mellor CJ, Mayer M, Rahmani M. Optical Monitoring of In Situ Iron Loading into Single, Native Ferritin Proteins. NANO LETTERS 2023; 23:3251-3258. [PMID: 37053043 PMCID: PMC10141409 DOI: 10.1021/acs.nanolett.3c00042] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Ferritin is a protein that stores and releases iron to prevent diseases associated with iron dysregulation in plants, animals, and bacteria. The conversion between iron-loaded holo-ferritin and empty apo-ferritin is an important process for iron regulation. To date, studies of ferritin have used either ensemble measurements to quantify the characteristics of a large number of proteins or single-molecule approaches to interrogate labeled or modified proteins. Here we demonstrate the first real-time study of the dynamics of iron ion loading and biomineralization within a single, unlabeled ferritin protein. Using optical nanotweezers, we trapped single apo- and holo-ferritins indefinitely, distinguished one from the other, and monitored their structural dynamics in real time. The study presented here deepens the understanding of the iron uptake mechanism of ferritin proteins, which may lead to new therapeutics for iron-related diseases.
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Affiliation(s)
- Arman Yousefi
- Advanced
Optics and Photonics Laboratory, Department of Engineering, School
of Science and Technology, Nottingham Trent
University, Nottingham NG118 NS, United
Kingdom
| | - Cuifeng Ying
- Advanced
Optics and Photonics Laboratory, Department of Engineering, School
of Science and Technology, Nottingham Trent
University, Nottingham NG118 NS, United
Kingdom
- Email
for C.Y.:
| | | | - Mahya Assadipapari
- Advanced
Optics and Photonics Laboratory, Department of Engineering, School
of Science and Technology, Nottingham Trent
University, Nottingham NG118 NS, United
Kingdom
| | - Gabriel Sanderson
- Advanced
Optics and Photonics Laboratory, Department of Engineering, School
of Science and Technology, Nottingham Trent
University, Nottingham NG118 NS, United
Kingdom
| | - Ze Zheng
- Advanced
Optics and Photonics Laboratory, Department of Engineering, School
of Science and Technology, Nottingham Trent
University, Nottingham NG118 NS, United
Kingdom
| | - Lei Xu
- Advanced
Optics and Photonics Laboratory, Department of Engineering, School
of Science and Technology, Nottingham Trent
University, Nottingham NG118 NS, United
Kingdom
| | - Saaman Zargarbashi
- Advanced
Optics and Photonics Laboratory, Department of Engineering, School
of Science and Technology, Nottingham Trent
University, Nottingham NG118 NS, United
Kingdom
| | - Graham J. Hickman
- School
of Science and Technology, Nottingham Trent
University, Nottingham NG11 8NS, United
Kingdom
| | - Richard B. Cousins
- Nanoscale
and Microscale Research Centre, University
of Nottingham, Nottingham NG7 2RD, United
Kingdom
| | - Christopher J. Mellor
- School
of Physics and Astronomy, University of
Nottingham, Nottingham NG7 2RD, United
Kingdom
| | - Michael Mayer
- Adolphe
Merkle Institute, University of Fribourg, Chemin des Verdiers 4, CH-1700 Fribourg, Switzerland
| | - Mohsen Rahmani
- Advanced
Optics and Photonics Laboratory, Department of Engineering, School
of Science and Technology, Nottingham Trent
University, Nottingham NG118 NS, United
Kingdom
- Email for M.R.:
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Oliveira NFB, Rodrigues FEP, Vitorino JNM, Loureiro RJS, Faísca PFN, Machuqueiro M. Predicting stable binding modes from simulated dimers of the D76N mutant of β 2-microglobulin. Comput Struct Biotechnol J 2021; 19:5160-5169. [PMID: 34630936 PMCID: PMC8473664 DOI: 10.1016/j.csbj.2021.09.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 09/02/2021] [Accepted: 09/02/2021] [Indexed: 11/16/2022] Open
Abstract
β2m D76N mutant populates an aggregation-prone monomer (I2) with unstructured termini. MD and MM-PBSA indicate that I2 dimers are stabilized by hydrophobic interactions. The termini regions and BC- and DE-loops are prevalent in the most stable interfaces. The most stable dimer has a limited growth potential without structural rearrangement.
The D76N mutant of the β2m protein is a biologically motivated model system to study protein aggregation. There is strong experimental evidence, supported by molecular simulations, that D76N populates a highly dynamic conformation (which we originally named I2) that exposes aggregation-prone patches as a result of the detachment of the two terminal regions. Here, we use Molecular Dynamics simulations to study the stability of an ensemble of dimers of I2 generated via protein–protein docking. MM-PBSA calculations indicate that within the ensemble of investigated dimers the major contribution to interface stabilization at physiological pH comes from hydrophobic interactions between apolar residues. Our structural analysis also reveals that the interfacial region associated with the most stable binding modes are particularly rich in residues pertaining to both the N- and C-terminus, as well residues from the BC- and DE-loops. On the other hand, the less stable interfaces are stabilized by intermolecular interactions involving residues from the CD- and EF-loops. By focusing on the most stable binding modes, we used a simple geometric rule to propagate the corresponding dimer interfaces. We found that, in the absence of any kind of structural rearrangement occurring at an early stage of the oligomerization pathway, some interfaces drive a self-limited growth process, while others can be propagated indefinitely allowing the formation of long, polymerized chains. In particular, the interfacial region of the most stable binding mode reported here falls in the class of self-limited growth.
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Affiliation(s)
- Nuno F B Oliveira
- BioISI - Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Campo Grande, C8 bdg, Lisboa 1749-016, Portugal.,Department of Chemistry and Biochemistry, Faculty of Sciences, University of Lisbon, Lisboa 1749-016, Portugal
| | - Filipe E P Rodrigues
- BioISI - Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Campo Grande, C8 bdg, Lisboa 1749-016, Portugal.,Department of Chemistry and Biochemistry, Faculty of Sciences, University of Lisbon, Lisboa 1749-016, Portugal
| | - João N M Vitorino
- BioISI - Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Campo Grande, C8 bdg, Lisboa 1749-016, Portugal.,Department of Chemistry and Biochemistry, Faculty of Sciences, University of Lisbon, Lisboa 1749-016, Portugal
| | - Rui J S Loureiro
- BioISI - Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Campo Grande, C8 bdg, Lisboa 1749-016, Portugal
| | - Patrícia F N Faísca
- BioISI - Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Campo Grande, C8 bdg, Lisboa 1749-016, Portugal.,Department of Physics, Faculty of Sciences, University of Lisbon, Lisbon 1749-016, Portugal
| | - Miguel Machuqueiro
- BioISI - Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Campo Grande, C8 bdg, Lisboa 1749-016, Portugal.,Department of Chemistry and Biochemistry, Faculty of Sciences, University of Lisbon, Lisboa 1749-016, Portugal
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Morand J, Nunes A, Faísca PFN. The folding space of protein β2-microglobulin is modulated by a single disulfide bridge. Phys Biol 2021; 18. [PMID: 34098544 DOI: 10.1088/1478-3975/ac08ec] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 06/07/2021] [Indexed: 11/11/2022]
Abstract
Protein beta-2-microglobulin (β2m) is classically considered the causative agent of dialysis related amyloidosis, a conformational disorder that affects patients undergoing long-term hemodialysis. The wild type (WT) form, the ΔN6 structural variant, and the D76N mutant have been extensively used as model systems ofβ2m aggregation. In all of them, the native structure is stabilized by a disulfide bridge between the sulphur atoms of the cysteine residues 25 (at B strand) and 80 (at F strand), which has been considered fundamental inβ2m fibrillogenesis. Here, we use extensive discrete molecular dynamics simulations of a full atomistic structure-based model to explore the role of this disulfide bridge as a modulator of the folding space ofβ2m. In particular, by considering different models for the disulfide bridge, we explore the thermodynamics of the folding transition, and the formation of intermediate states that may have the potential to trigger the aggregation cascade. Our results show that the dissulfide bridge affects folding transition and folding thermodynamics of the considered model systems, although to different extents. In particular, when the interaction between the sulphur atoms is stabilized relative to the other intramolecular interactions, or even locked (i.e. permanently established), the WT form populates an intermediate state featuring a well preserved core and two unstructured termini, which was previously detected only for the D76N mutant. The formation of this intermediate state may have important implications in our understanding ofβ2m fibrillogenesis.
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Affiliation(s)
- Jules Morand
- Departamento de Física and BioISI - Biosystems and Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, CampoGrande, Ed. C8, 1749-016 Lisboa, Portugal
| | - Ana Nunes
- Departamento de Física and BioISI - Biosystems and Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, CampoGrande, Ed. C8, 1749-016 Lisboa, Portugal
| | - Patrícia F N Faísca
- Departamento de Física and BioISI - Biosystems and Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, CampoGrande, Ed. C8, 1749-016 Lisboa, Portugal
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