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Muroni A, Minicozzi V, Piro MC, Sinibaldi F, Mei G, Di Venere A. Human cytochrome C natural variants: Studying the membrane binding properties of G41S and Y48H by fluorescence energy transfer and molecular dynamics. Int J Biol Macromol 2024; 274:133371. [PMID: 38914400 DOI: 10.1016/j.ijbiomac.2024.133371] [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: 05/06/2024] [Revised: 06/21/2024] [Accepted: 06/21/2024] [Indexed: 06/26/2024]
Abstract
Cytochrome C (cyt C), the protein involved in oxidative phosphorylation, plays several other crucial roles necessary for both cell life and death. Studying natural variants of cyt C offers the possibility to better characterize the structure-to-function relationship that modulates the different activities of this protein. Naturally mutations in human cyt C (G41S and Y48H) occur in the protein central Ω-loop and cause thrombocytopenia 4. In this study, we have investigated the binding of such variants and of wild type (wt) cyt C to synthetic cardiolipin-containing vesicles. The mutants have a lower propensity in membrane binding, displaying higher dissociation constants with respect to the wt protein. Compressibility measurements reveal that both variants are more flexible than the wt, suggesting that the native central Ω-loop is important for the interaction with membranes. Such hypothesis is supported by molecular dynamics simulations. A minimal distance analysis indicates that in the presence of cardiolipin the central Ω-loop of the mutants is no more in contact with the membrane, as it happens instead in the case of wt cyt C. Such finding might provide a hint for the reduced membrane binding capacity of the variants and their enhanced peroxidase activity in vivo.
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Affiliation(s)
- Alessia Muroni
- Department of Physics, University of Rome Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome, Italy
| | - Velia Minicozzi
- Department of Physics, University of Rome Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome, Italy; INFN, Section of Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome, Italy
| | - Maria Cristina Piro
- Department of Experimental Medicine, University of Rome Tor Vergata, Via Montpellier 1, 00133 Rome, Italy
| | - Federica Sinibaldi
- Department of Experimental Medicine, University of Rome Tor Vergata, Via Montpellier 1, 00133 Rome, Italy
| | - Giampiero Mei
- Department of Experimental Medicine, University of Rome Tor Vergata, Via Montpellier 1, 00133 Rome, Italy.
| | - Almerinda Di Venere
- Department of Experimental Medicine, University of Rome Tor Vergata, Via Montpellier 1, 00133 Rome, Italy.
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Martin WJ, McClelland LJ, Nold SM, Boshae KL, Bowler BE. Effect of proline content and histidine ligation on the dynamics of Ω-loop D and the peroxidase activity of iso-1-cytochrome c. J Inorg Biochem 2024; 252:112474. [PMID: 38176365 DOI: 10.1016/j.jinorgbio.2023.112474] [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: 10/16/2023] [Revised: 12/20/2023] [Accepted: 12/20/2023] [Indexed: 01/06/2024]
Abstract
To study how proline residues affect the dynamics of Ω-loop D (residues 70 to 85) of cytochrome c, we prepared G83P and G83A variants of yeast iso-1-cytochrome c (iso-1-Cytc) in the presence and absence of a K73H mutation. Ω-loop D is important in controlling both the electron transfer function of Cytc and the peroxidase activity of Cytc used in apoptosis because it provides the Met80 heme ligand. The G83P and G83A mutations have no effect on the global stability of iso-1-Cytc in presence or absence of the K73H mutation. However, both mutations destabilize the His73-mediated alkaline conformer relative to the native state. pH jump stopped-flow experiments show that the dynamics of the His73-mediated alkaline transition are significantly enhanced by the G83P mutation. Gated electron transfer studies show that the enhanced dynamics result from an increased rate of return to the native state, whereas the rate of loss of Met80 ligation is unchanged by the G83P mutation. Thus, the G83P substitution does not stiffen the conformation of the native state. Because bis-His heme ligation occurs when Cytc binds to cardiolipin-containing membranes, we studied the effect of His73 ligation on the peroxidase activity of Cytc, which acts as an early signal in apoptosis by causing oxygenation of cardiolipin. We find that the His73 alkaline conformer suppresses the peroxidase activity of Cytc. Thus, the bis-His ligated state of Cytc formed upon binding to cardiolipin is a negative effector for the peroxidase activity of Cytc early in apoptosis.
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Affiliation(s)
- William J Martin
- Department of Chemistry & Biochemistry, University of Montana, Missoula, MT 59812, United States
| | - Levi J McClelland
- Department of Chemistry & Biochemistry, University of Montana, Missoula, MT 59812, United States; Division of Biological Sciences, University of Montana, Missoula, MT 59812, United States; Center for Biomolecular Structure & Dynamics, University of Montana, Missoula, MT 59812, United States
| | - Shiloh M Nold
- Department of Chemistry & Biochemistry, University of Montana, Missoula, MT 59812, United States
| | - Kassandra L Boshae
- Department of Chemistry & Biochemistry, University of Montana, Missoula, MT 59812, United States
| | - Bruce E Bowler
- Department of Chemistry & Biochemistry, University of Montana, Missoula, MT 59812, United States; Center for Biomolecular Structure & Dynamics, University of Montana, Missoula, MT 59812, United States.
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Nutho B, Samsri S, Pornsuwan S. Structural Dynamics of the Precatalytic State of Human Cytochrome c upon T28C, G34C, and A50C Mutations: A Molecular Dynamics Simulation Perspective. ACS OMEGA 2023; 8:15229-15238. [PMID: 37151554 PMCID: PMC10157674 DOI: 10.1021/acsomega.3c00220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 04/06/2023] [Indexed: 05/09/2023]
Abstract
The native structure of cytochrome c (cytc) contains hexacoordinate heme iron with His18 and Met80 residues ligated at the axial sites. Mutations of cytc at Ω-loops have been investigated in modulating the peroxidase activity and, hence, related to the initiation of the apoptotic pathway. Our previous experimental data reported on the peroxidase activity of the cysteine-directed mutants at different parts of the Ω-loop of human cytc (hCytc), that is, T28C, G34C, and A50C. In this work, we performed 1 μs molecular dynamics (MD) simulations to elucidate the detailed structural and dynamic changes upon these mutations, particularly at the proximal Ω-loop. The structures of hCytc were modeled in the hexacoordinated form, which was referred to as the "precatalytic state". The results showed that the structural features of the G34C mutant were more distinctive than those of other mutants. G34C mutation caused local destabilization and flexibility at the proximal Ω-loop (residues 12-28) and an extended distance between this Ω-loop region and heme iron. Besides, analysis of the orientation of the Arg38 side chain of the G34C mutant revealed the Arg38 conformer facing away from the heme iron. The obtained MD results also suggested structural diversity of the precatalytic states for the three hCytc mutants, specifically the effect of G34C mutation on the flexibility of the proximal Ω-loops. Therefore, our MD simulations combined with previous experimental data provide detailed insights into the structural basis of hCytc that could contribute to its pro-apoptotic function.
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Affiliation(s)
- Bodee Nutho
- Department
of Pharmacology, Faculty of Science, Mahidol
University, Bangkok 10400, Thailand
| | - Sasiprapa Samsri
- Department
of Chemistry and Center of Excellence for Innovation in Chemistry,
Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Soraya Pornsuwan
- Department
of Chemistry and Center of Excellence for Innovation in Chemistry,
Faculty of Science, Mahidol University, Bangkok 10400, Thailand
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Feng Y, Liu XC, Li L, Gao SQ, Wen GB, Lin YW. Naturally Occurring I81N Mutation in Human Cytochrome c Regulates Both Inherent Peroxidase Activity and Interactions with Neuroglobin. ACS OMEGA 2022; 7:11510-11518. [PMID: 35415373 PMCID: PMC8992277 DOI: 10.1021/acsomega.2c01256] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 03/14/2022] [Indexed: 05/24/2023]
Abstract
Human cytochrome c (hCyt c) is a crucial heme protein and plays an indispensable role in energy conversion and intrinsic apoptosis pathways. The sequence and structure of Cyt c were evolutionarily conserved and only a few naturally occurring mutants were detected in humans. Among those variable sites, position 81 was proposed to act as a peroxidase switch in the initiation stages of apoptosis. In this study, we show that Ile81 not only suppresses the intrinsic peroxidase activity but also is essential for Cyt c to interact with neuroglobin (Ngb), a potential protein partner. The kinetic assays showed that the peroxidase activity of the naturally occurring variant I81N was enhanced up to threefold under pH 5. The local stability of the Ω-loop D (residues 70-85) in the I81N variant was decreased. Moreover, the Alphafold2 program predicted that Ile81 forms stable contact with human Ngb. Meanwhile, the Ile81 to Asn81 missense mutation abolishes the interaction interface, resulting in a ∼40-fold decrease in binding affinity. These observations provide an insight into the structure-function relationship of the conserved Ile81 in vertebrate Cyt c.
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Affiliation(s)
- Yu Feng
- School
of Chemistry and Chemical Engineering, University
of South China, Hengyang 421001, China
| | - Xi-Chun Liu
- School
of Chemistry and Chemical Engineering, University
of South China, Hengyang 421001, China
| | - Lianzhi Li
- School
of Chemistry and Chemical Engineering, Liaocheng
University, Liaocheng 252059, China
| | - Shu-Qin Gao
- Key
Lab of Protein Structure and Function of Universities in Hunan Province, University of South China, Hengyang 421001, China
| | - Ge-Bo Wen
- Key
Lab of Protein Structure and Function of Universities in Hunan Province, University of South China, Hengyang 421001, China
| | - Ying-Wu Lin
- School
of Chemistry and Chemical Engineering, University
of South China, Hengyang 421001, China
- Key
Lab of Protein Structure and Function of Universities in Hunan Province, University of South China, Hengyang 421001, China
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Effect on intrinsic peroxidase activity of substituting coevolved residues from Ω-loop C of human cytochrome c into yeast Iso-1-cytochrome c. J Inorg Biochem 2022; 232:111819. [DOI: 10.1016/j.jinorgbio.2022.111819] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 03/25/2022] [Accepted: 04/02/2022] [Indexed: 11/15/2022]
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Samsri S, Prasertsuk P, Nutho B, Pornsuwan S. Molecular insights on the conformational dynamics of a P76C mutant of human cytochrome c and the enhancement on its peroxidase activity. Arch Biochem Biophys 2021; 716:109112. [PMID: 34954215 DOI: 10.1016/j.abb.2021.109112] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 12/17/2021] [Accepted: 12/20/2021] [Indexed: 11/16/2022]
Abstract
In apoptotic pathway, the interaction of Cytochrome c (Cytc) with cardiolipin in vivo is a key process to induce peroxidase activity of Cytc and trigger the release of Cytc in the inner mitochondria into cytosol. The peroxidase active form of Cytc occurs due to local conformational changes that support the opening of the heme crevice and the loss of an axial ligand between Met80 and heme Fe. Structural adjustments at the Ω-loop segments of Cytc are required for such process. To study the role of the distal Ω-loop segments comprising residues 71-85 in human Cytc (hCytc), we investigated a cysteine mutation at Pro76, one of the highly conserved residues in this loop. The effect of P76C mutant was explored by the combination of experimental characterizations and molecular dynamics (MD) simulations. The peroxidase activity of the P76C mutant was found to be significantly increased by ∼13 folds relative to the wild type. Experimental data on global denaturation, alkaline transition, heme bleaching, and spin-labeling Electron Spin Resonance were in good agreement with the enhancement of peroxidase activity. The MD results of hCytc in the hexacoordinate form suggest the important changes in P76C mutant occurred due to the unfolding at the central Ω-loop (residues 40-57), and the weakening of H-bond between Tyr67 and Met80. Whereas the experimental data implied that the P76C mutant tend to be in equilibrium between the pentacoordinate and hexacoordinate forms, the MD and experimental information are complementary and were used to support the mechanisms of peroxidase active form of hCytc.
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Affiliation(s)
- Sasiprapa Samsri
- Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| | - Possawee Prasertsuk
- Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| | - Bodee Nutho
- Department of Pharmacology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand.
| | - Soraya Pornsuwan
- Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand.
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