1
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Mondal S, Das B. A study on the interaction of horse heart cytochrome c with some conventional and ionic liquid surfactants probed by ultraviolet-visible and fluorescence spectroscopic techniques. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2018; 198:278-282. [PMID: 29554518 DOI: 10.1016/j.saa.2018.03.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 02/19/2018] [Accepted: 03/11/2018] [Indexed: 06/08/2023]
Abstract
The interactions of a protein cytochrome c with some selected conventional and ionic liquid surfactants have been investigated at pH7.4 using ultraviolet-visible and fluorescence spectroscopic techniques. We used four conventional surfactants - cetyltrimethylammonium bromide (CTAB), dodecyltrimethylammonium bromide (DTAB), sodium N-dodecanoylsarcosinate (SDDS), and N-decanoyl-N-methylglucamine (Mega 10), and a surface active ionic liquid 1-hexadecyl-3-methylimidazolium chloride (C16MeImCl). All the investigated surfactants were found to induce an unfolding of the protein cytochrome c. In presence of CTAB, SDDS and C16MeImCl, the heme iron atom was found to loose methionine from its axial position. Differential binding of the surfactant monomers and their micelles to the protein molecules was inferred. The ionic surfactants were found to be more effective than the nonionic one in unfolding the investigated protein. However, the extent of binding of CTAB/C16MeImCl to cytochrome c reaches a plateau past the critical micellization concentration (cmc) of the surfactant. For each of the cytochrome c-DTAB, cytochrome c-SDDS and cytochrome c-Mega 10 system, although there exists an inflection in the surfactant-binding, saturation point could not be detected. It has been demonstrated from the ultraviolet-visible spectral studies that the oxidation state of iron in cytochrome c does not change when the protein binds with the investigated surfactants.
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Affiliation(s)
- Satyajit Mondal
- Department of Chemistry, Presidency University, Kolkata 700 073, India
| | - Bijan Das
- Department of Chemistry, Presidency University, Kolkata 700 073, India.
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2
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Mara MW, Hadt RG, Reinhard ME, Kroll T, Lim H, Hartsock RW, Alonso-Mori R, Chollet M, Glownia JM, Nelson S, Sokaras D, Kunnus K, Hodgson KO, Hedman B, Bergmann U, Gaffney KJ, Solomon EI. Metalloprotein entatic control of ligand-metal bonds quantified by ultrafast x-ray spectroscopy. Science 2018. [PMID: 28642436 DOI: 10.1126/science.aam6203] [Citation(s) in RCA: 91] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The multifunctional protein cytochrome c (cyt c) plays key roles in electron transport and apoptosis, switching function by modulating bonding between a heme iron and the sulfur in a methionine residue. This Fe-S(Met) bond is too weak to persist in the absence of protein constraints. We ruptured the bond in ferrous cyt c using an optical laser pulse and monitored the bond reformation within the protein active site using ultrafast x-ray pulses from an x-ray free-electron laser, determining that the Fe-S(Met) bond enthalpy is ~4 kcal/mol stronger than in the absence of protein constraints. The 4 kcal/mol is comparable with calculations of stabilization effects in other systems, demonstrating how biological systems use an entatic state for modest yet accessible energetics to modulate chemical function.
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Affiliation(s)
- Michael W Mara
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA.,Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Ryan G Hadt
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA
| | - Marco Eli Reinhard
- PULSE Institute, SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305, USA
| | - Thomas Kroll
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, 2575 Sand Hill Road, Menlo Park, CA 94025, USA.,Linac Coherent Light Source, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025, USA
| | - Hyeongtaek Lim
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA.,Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Robert W Hartsock
- PULSE Institute, SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305, USA
| | - Roberto Alonso-Mori
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025, USA
| | - Matthieu Chollet
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025, USA
| | - James M Glownia
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025, USA
| | - Silke Nelson
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025, USA
| | - Dimosthenis Sokaras
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, 2575 Sand Hill Road, Menlo Park, CA 94025, USA.,Linac Coherent Light Source, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025, USA
| | - Kristjan Kunnus
- PULSE Institute, SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305, USA
| | - Keith O Hodgson
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA.,Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Britt Hedman
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
| | - Uwe Bergmann
- PULSE Institute, SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305, USA.,Linac Coherent Light Source, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025, USA
| | - Kelly J Gaffney
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, 2575 Sand Hill Road, Menlo Park, CA 94025, USA.,PULSE Institute, SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305, USA
| | - Edward I Solomon
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA. .,Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
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3
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Firsov AM, Kotova EA, Orlov VN, Antonenko YN, Skulachev VP. A mitochondria-targeted antioxidant can inhibit peroxidase activity of cytochromecby detachment of the protein from liposomes. FEBS Lett 2016; 590:2836-43. [DOI: 10.1002/1873-3468.12319] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 07/14/2016] [Accepted: 07/14/2016] [Indexed: 11/08/2022]
Affiliation(s)
- Alexander M. Firsov
- Belozersky Institute of Physico-Chemical Biology; Lomonosov Moscow State University; Russia
- Department of Bioengineering and Bioinformatics; Lomonosov Moscow State University; Russia
| | - Elena A. Kotova
- Belozersky Institute of Physico-Chemical Biology; Lomonosov Moscow State University; Russia
| | - Viktor N. Orlov
- Belozersky Institute of Physico-Chemical Biology; Lomonosov Moscow State University; Russia
| | - Yuri N. Antonenko
- Belozersky Institute of Physico-Chemical Biology; Lomonosov Moscow State University; Russia
| | - Vladimir P. Skulachev
- Belozersky Institute of Physico-Chemical Biology; Lomonosov Moscow State University; Russia
- Department of Bioengineering and Bioinformatics; Lomonosov Moscow State University; Russia
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4
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Peroxidative permeabilization of liposomes induced by cytochrome c/cardiolipin complex. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:767-74. [DOI: 10.1016/j.bbamem.2014.11.027] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 11/21/2014] [Accepted: 11/25/2014] [Indexed: 01/23/2023]
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5
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Bharmoria P, Trivedi TJ, Pabbathi A, Samanta A, Kumar A. Ionic liquid-induced all-α to α + β conformational transition in cytochrome c with improved peroxidase activity in aqueous medium. Phys Chem Chem Phys 2015; 17:10189-99. [DOI: 10.1039/c4cp06044j] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Choline dioctylsulfosuccinate [Cho][AOT] (a surface active ionic liquid) has been found to induce all-α to α + β conformational transition in the secondary structure of enzyme cytochrome c (Cyt c) with an enhanced peroxidase activity in its aqueous vesicular phase at pH 7.0.
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Affiliation(s)
- Pankaj Bharmoria
- Academy of Scientific and Innovative research (AcSIR)
- Central Salt and Marine Chemicals Research Institute
- Council of Scientific and Industrial Research (CSIR)
- Bhavnagar-364002
- India
| | - Tushar J. Trivedi
- Graduate School of EEWS (Energy Environment Water Sustainability)
- KAIST
- Daejeon 305-701
- Republic of Korea
| | - Ashok Pabbathi
- School of Chemistry
- University of Hyderabad
- Hyderabad 500 046
- India
| | - Anunay Samanta
- School of Chemistry
- University of Hyderabad
- Hyderabad 500 046
- India
| | - Arvind Kumar
- Academy of Scientific and Innovative research (AcSIR)
- Central Salt and Marine Chemicals Research Institute
- Council of Scientific and Industrial Research (CSIR)
- Bhavnagar-364002
- India
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6
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Zaidi S, Hassan MI, Islam A, Ahmad F. The role of key residues in structure, function, and stability of cytochrome-c. Cell Mol Life Sci 2014; 71:229-55. [PMID: 23615770 PMCID: PMC11113841 DOI: 10.1007/s00018-013-1341-1] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Revised: 04/05/2013] [Accepted: 04/08/2013] [Indexed: 02/06/2023]
Abstract
Cytochrome-c (cyt-c), a multi-functional protein, plays a significant role in the electron transport chain, and thus is indispensable in the energy-production process. Besides being an important component in apoptosis, it detoxifies reactive oxygen species. Two hundred and eighty-five complete amino acid sequences of cyt-c from different species are known. Sequence analysis suggests that the number of amino acid residues in most mitochondrial cyts-c is in the range 104 ± 10, and amino acid residues at only few positions are highly conserved throughout evolution. These highly conserved residues are Cys14, Cys17, His18, Gly29, Pro30, Gly41, Asn52, Trp59, Tyr67, Leu68, Pro71, Pro76, Thr78, Met80, and Phe82. These are also known as "key residues", which contribute significantly to the structure, function, folding, and stability of cyt-c. The three-dimensional structure of cyt-c from ten eukaryotic species have been determined using X-ray diffraction studies. Structure analysis suggests that the tertiary structure of cyt-c is almost preserved along the evolutionary scale. Furthermore, residues of N/C-terminal helices Gly6, Phe10, Leu94, and Tyr97 interact with each other in a specific manner, forming an evolutionary conserved interface. To understand the role of evolutionary conserved residues on structure, stability, and function, numerous studies have been performed in which these residues were substituted with different amino acids. In these studies, structure deals with the effect of mutation on secondary and tertiary structure measured by spectroscopic techniques; stability deals with the effect of mutation on T m (midpoint of heat denaturation), ∆G D (Gibbs free energy change on denaturation) and folding; and function deals with the effect of mutation on electron transport, apoptosis, cell growth, and protein expression. In this review, we have compiled all these studies at one place. This compilation will be useful to biochemists and biophysicists interested in understanding the importance of conservation of certain residues throughout the evolution in preserving the structure, function, and stability in proteins.
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Affiliation(s)
- Sobia Zaidi
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025 India
| | - Md. Imtaiyaz Hassan
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025 India
| | - Asimul Islam
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025 India
| | - Faizan Ahmad
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025 India
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7
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Arouri A, Dathe M, Blume A. The helical propensity of KLA amphipathic peptides enhances their binding to gel-state lipid membranes. Biophys Chem 2013; 180-181:10-21. [DOI: 10.1016/j.bpc.2013.05.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Revised: 05/17/2013] [Accepted: 05/18/2013] [Indexed: 12/18/2022]
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8
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Zaragoza A, Teruel JA, Aranda FJ, Marqués A, Espuny MJ, Manresa Á, Ortiz A. Interaction of a Rhodococcus sp. trehalose lipid biosurfactant with model proteins: thermodynamic and structural changes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:1381-90. [PMID: 22172005 DOI: 10.1021/la203879t] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
One major application of surfactants is to prevent aggregation during various processes of protein manipulation. In this work, a bacterial trehalose lipid (TL) with biosurfactant activity, secreted by Rhodococcus sp., has been identified and purified. The interactions of this glycolipid with selected model proteins have been studied by using differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR) spectroscopy, isothermal titration calorimetry (ITC), and fluorescence spectroscopy. Bovine serum albumin (BSA) and cytochrome c (Cyt-c) have been chosen because of their quite different secondary structures: BSA contains essentially no β-sheets and an average 66% α-helix, whereas Cyt-c possesses up to 25% β-sheets and up to 45% α-helical structure. Differential scanning calorimetry shows that addition of TL to BSA at concentrations below the critical micelle concentration (cmc) shifts the thermal unfolding temperature to higher values. FTIR indicates that TL does not alter the secondary structure of native BSA, but the presence of TL protects the protein toward thermal denaturation, mainly by avoiding formation of β-aggregates. Studies on the intrinsic Trp fluorescence of BSA show that addition of TL to the native protein results in conformational changes. BSA unfolding upon thermal denaturation in the absence of TL makes the Trp residues less accessible to the quencher, as shown by a decrease in the value of Stern-Volmer dynamic quenching constant, whereas denaturation in the presence of the biosurfactant prevents unfolding, in agreement with FTIR results. In the case of Cyt-c, interaction with TL gives rise to a new thermal denaturation transition, as observed by DSC, at temperatures below that of the native protein, therefore facilitating thermal unfolding. Binding of TL to native BSA and Cyt-c, as determined by ITC, suggests a rather nonspecific interaction of the biosurfactant with both proteins. FTIR indicates that TL slightly modifies the secondary structure of native Cyt-c, but protein denaturation in the presence of TL results in a higher proportion of β-aggregates than in its absence (20% vs 3.9%). The study of Trp fluorescence upon TL addition to Cyt-c results in a completely opposite scenario to that described above for BSA. In this case, addition of TL considerably increases the value of the dynamic quenching constant, both in native and denatured protein; that is, the interaction with the glycolipid induces conformational changes which facilitate the exposure of Trp residues to the quencher. Considering the structures of both proteins, it could be derived that the characteristics of TL interactions, either promoting or avoiding thermal unfolding, are highly dependent on the protein secondary structure. Our results also suggest the rather unspecific nature of these interactions. These might well involve protein hydrophobic domains which, being buried into the protein native structures, become exposed upon thermal unfolding.
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Affiliation(s)
- Ana Zaragoza
- Departamento de Bioquímica y Biología Molecular-A, Facultad de Veterinaria, Universidad de Murcia , E-30100 Murcia, Spain
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9
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Inhibition of mitochondrial fusion by α-synuclein is rescued by PINK1, Parkin and DJ-1. EMBO J 2010; 29:3571-89. [PMID: 20842103 DOI: 10.1038/emboj.2010.223] [Citation(s) in RCA: 370] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Accepted: 08/12/2010] [Indexed: 11/09/2022] Open
Abstract
Aggregation of α-synuclein (αS) is involved in the pathogenesis of Parkinson's disease (PD) and a variety of related neurodegenerative disorders. The physiological function of αS is largely unknown. We demonstrate with in vitro vesicle fusion experiments that αS has an inhibitory function on membrane fusion. Upon increased expression in cultured cells and in Caenorhabditis elegans, αS binds to mitochondria and leads to mitochondrial fragmentation. In C. elegans age-dependent fragmentation of mitochondria is enhanced and shifted to an earlier time point upon expression of exogenous αS. In contrast, siRNA-mediated downregulation of αS results in elongated mitochondria in cell culture. αS can act independently of mitochondrial fusion and fission proteins in shifting the dynamic morphologic equilibrium of mitochondria towards reduced fusion. Upon cellular fusion, αS prevents fusion of differently labelled mitochondrial populations. Thus, αS inhibits fusion due to its unique membrane interaction. Finally, mitochondrial fragmentation induced by expression of αS is rescued by coexpression of PINK1, parkin or DJ-1 but not the PD-associated mutations PINK1 G309D and parkin Δ1-79 or by DJ-1 C106A.
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10
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del Carmen Puga Molina L, Verstraeten SV. Thallium(III)-mediated changes in membrane physical properties and lipid oxidation affect cardiolipin–cytochrome c interactions. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:2157-64. [DOI: 10.1016/j.bbamem.2008.04.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2008] [Revised: 04/16/2008] [Accepted: 04/29/2008] [Indexed: 10/22/2022]
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11
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Mechanism for stabilization of the molten globule state of papain by sodium n-alkyl sulfates: Spectroscopic and calorimetric approaches. J Colloid Interface Sci 2008; 322:119-27. [DOI: 10.1016/j.jcis.2008.03.001] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2007] [Revised: 02/29/2008] [Accepted: 03/01/2008] [Indexed: 11/17/2022]
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12
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Kalanxhi E, Wallace C. Cytochrome c impaled: investigation of the extended lipid anchorage of a soluble protein to mitochondrial membrane models. Biochem J 2008; 407:179-87. [PMID: 17614790 PMCID: PMC2049027 DOI: 10.1042/bj20070459] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Cyt c (cytochrome c) has been traditionally envisioned as rapidly diffusing in two dimensions at the surface of the mitochondrial inner membrane when not engaged in redox reactions with physiological partners. However, the discovery of the extended lipid anchorage (insertion of an acyl chain of a bilayer phospholipid into the protein interior) suggests that this may not be exclusively the case. The physical and structural factors underlying the conformational changes that occur upon interaction of ferrous cyt c with phospholipid membrane models have been investigated by monitoring the extent of the spin state change that result from this interaction. Once transiently linked by electrostatic forces between basic side chains and phosphate groups, the acyl chain entry may occur between two parallel hydrophobic polypeptide stretches that are surrounded by positively charged residues. Alteration of these charges, as in the case of non-trimethylated (TML72K) yeast cyt c and Arg91Nle horse cyt c (where Nle is norleucine), led to a decline in the binding affinity for the phospholipid liposomes. The electrostatic association was sensitive to ionic strength, polyanions and pH, whereas the hydrophobic interactions were enhanced by conformational changes that contributed to the loosening of the tertiary structure of cyt c. In addition to proposing a mechanistic model for the extended lipid anchorage of cyt c, we consider what, if any, might be the physiological relevance of the phenomenon.
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Affiliation(s)
- Erta Kalanxhi
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, Canada B3H1X5
| | - Carmichael J. A. Wallace
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, Canada B3H1X5
- To whom correspondence should be addressed (email )
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Sedlák E. Characterization of the polyanion-induced molten globule-like state of cytochromec. Biopolymers 2007; 86:119-26. [PMID: 17330862 DOI: 10.1002/bip.20710] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Cytochrome c (cyt c) undergoes a poly(vinylsulphate) (PVS)-induced transition at slightly acidic pH into a molten globule-like state that resembles the effect that negatively charged membrane surfaces have on this protein. In this work, the thermodynamic properties of the molten globule-like state of cyt c in complex with PVS are studied using differential scanning calorimetry, circular dichroism, fluorescence, and absorbance spectroscopy. The temperature-induced transition of the molten globule-like state of cyt c in the complex with PVS is characterized by a significantly lower calorimetric enthalpy than in the "typical" molten globule state of cyt c, i.e. free protein at pH 2.0 in high ionic strength. Moreover, the thermally-denatured state of cyt c in the complex at pH < 6 contains nearly 50% of the native secondary structure. The dependence of the transition temperature on the pH indicates a role for histidine residues in the destabilization of the cyt c structure in the PVS complex and in stabilization of the denatured state with the residual secondary structure. A comparison of the effects of small anions and polyanions demonstrates the importance of cooperativity among the anions in the destabilization of cyt c. Predictably, other hydrophilic flexible polyanions such as heparin, polyglutamate, and polyadenylate also have a destabilizing effect on the structure of cyt c. However, a correlation between the properties of the polyanions and their effect on the protein stability is still unclear.
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Affiliation(s)
- Erik Sedlák
- Department of Biochemistry, Faculty of Science UPJS, Moyzesova 11, 040 01 Kosice, Slovakia.
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14
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Epand RF, Tokarska-Schlattner M, Schlattner U, Wallimann T, Epand RM. Cardiolipin clusters and membrane domain formation induced by mitochondrial proteins. J Mol Biol 2006; 365:968-80. [PMID: 17097675 DOI: 10.1016/j.jmb.2006.10.028] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2006] [Revised: 10/04/2006] [Accepted: 10/08/2006] [Indexed: 11/29/2022]
Abstract
We show in this study that mitochondrial creatine kinase promotes segregation and clustering of cardiolipin in mixed membranes, a phenomenon that has been proposed to occur at contact sites in the mitochondria. This property of mitochondrial creatine kinase is dependent on the native octameric structure of the protein and does not occur after heat-denaturation or with the native dimeric form of the protein. Cardiolipin segregation was demonstrated by differential scanning calorimetry using membranes containing cardiolipin and either dipalmitoylphosphatidylethanolamine or 1-palmitoyl-2-oleoylphosphatidylethanolamine. Addition of the ubiquitous form of mitochondrial creatine kinase leads to the formation of a phosphatidylethanolamine-rich domain as a result of the protein binding preferentially to the cardiolipin. Such phase separation does not occur if cardiolipin is replaced with dioleoyl phosphatidylglycerol. Lipid phase separation is observed with other cardiolipin-binding proteins, including cytochrome c and, to a very small extent, with truncated Bid (t-Bid), as well as with the cationic polypeptide poly-L-lysine, but among these proteins the octameric form of mitochondrial creatine kinase is by far the most effective in causing segregation and clustering of cardiolipin. The proteins included in this study are found at mitochondrial contact sites where they are known to associate with cardiolipin. Domains in mitochondria enriched in cardiolipin play an important role in apoptosis and in energy flux processes.
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Affiliation(s)
- Raquel F Epand
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada L8N 3Z5
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15
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Minetti CASA, Remeta DP. Energetics of membrane protein folding and stability. Arch Biochem Biophys 2006; 453:32-53. [PMID: 16712771 DOI: 10.1016/j.abb.2006.03.023] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2006] [Accepted: 03/23/2006] [Indexed: 11/24/2022]
Abstract
The critical role of membrane proteins in a myriad of biological and physiological functions has spawned numerous investigations over the past several decades with the long-term goal of identifying the molecular origins and energetic forces that stabilize these proteins within the membrane. Parallel structural and thermodynamics studies on several systems have provided significant insight regarding the driving forces governing folding, assembly, insertion, and translocation of membrane proteins. The present review surveys families of membrane-associated proteins including alpha-helical and beta-barrel structures, viral surface receptors, and pore-forming toxins, citing representative proteins within each of these classes for further scrutiny in terms of structure-function relationships and global conformational stability. This overview presents seminal findings from pioneering studies on the energetics of membrane protein folding and stability to modern techniques that are exploiting the use of molecular genetics and single molecule studies. An overall consensus regarding the molecular origins of membrane protein stability is that a number of intrinsic properties resemble features of soluble proteins, yet there are distinct energetic differences arising from specific intra- and intermolecular interactions within the membrane. The combined efforts from structural, energetics, and dynamics approaches offer unique insights and improve our fundamental understanding of the driving forces dictating membrane protein folding and stability.
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Affiliation(s)
- Conceição A S A Minetti
- Rutgers-The State University of New Jersey, Department of Chemistry and Chemical Biology, Piscataway, NJ 08854, USA.
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16
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Oellerich S, Lecomte S, Paternostre M, Heimburg T, Hildebrandt P. Peripheral and Integral Binding of Cytochromecto Phospholipids Vesicles. J Phys Chem B 2004. [DOI: 10.1021/jp036799t] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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17
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Gorbenko GP, Domanov YA. Cytochrome c location in phosphatidylcholine/cardiolipin model membranes: resonance energy transfer study. Biophys Chem 2003; 103:239-49. [PMID: 12727286 DOI: 10.1016/s0301-4622(02)00319-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Resonance energy transfer between lipid-bound fluorescent probe 3-methoxybenzanthrone as a donor and heme group of cytochrome c as an acceptor has been examined to ascertain the protein disposition relative to the surface of model membranes composed of phosphatidylcholine and cardiolipin (10, 50 and 80 mol%). The model of energy transfer in membrane systems has been extended to the case of donors distributed between the two-bilayer leaflets and acceptors located at the outer monolayer taking into account the donor and acceptor orientational behavior. Assuming specific protein orientation relative to the membrane surface and varying lateral distance of the donor-acceptor closest approach in the range from 0 to 3.5 nm the limits for possible heme distances from the bilayer midplane have been found to be 0.8-3 nm (10 mol% CL), 0-2.6 nm (50 mol% CL), and 1.4-3.3 nm (80 mol% CL).
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Affiliation(s)
- Galina P Gorbenko
- V.N. Karazin Kharkiv National University, 4 Svobody Sq., Kharkiv 61077, Ukraine.
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18
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Rokitskaya TI, Kotova EA, Antonenko YN. Cytochrome c decelerates channel kinetics of negatively charged gramicidin due to electrostatic interaction. Biochem Biophys Res Commun 2003; 302:865-8. [PMID: 12646251 DOI: 10.1016/s0006-291x(03)00274-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The effect of cytochrome c on the kinetic properties of ion channels formed by O-pyromellitylgramicidin (OPg), the negatively charged analogue of gramicidin A (gA), in bilayer lipid membranes was studied by the method of sensitized photoinactivation. The addition of cytochrome c to both sides of the membrane caused substantial deceleration of the photoinactivation kinetics of OPg channels which expose three negative charges to the aqueous phase at both sides of the membrane. By contrast, the gA photoinactivation kinetics was unaltered by the addition of cytochrome c. Based on the sensitivity of the observed effect to the ionic strength of the bathing solution, the cytochrome c-induced deceleration of the OPg photoinactivation kinetics reflecting the increase in the OPg channel lifetime was ascribed to electrostatic interaction of positive charges of cytochrome c with negative charges of OPg that resulted in channel clustering. Formation of clusters of OPg channels was previously inferred to explain the polylysine effect on the OPg channel kinetics. The decelerating effect of cytochrome c on OPg channels was observed only at a high number of OPg channels in the membrane, thus suggesting that the interaction between cytochrome c and the charged transmembrane protein requires sufficiently high negative charge density on the surface of the membrane.
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Affiliation(s)
- Tatiana I Rokitskaya
- A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119992, Russia
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19
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Dimitrova MN, Matsumura H, Terezova N, Neytchev V. Binding of globular proteins to lipid membranes studied by isothermal titration calorimetry and fluorescence. Colloids Surf B Biointerfaces 2002. [DOI: 10.1016/s0927-7765(01)00248-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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20
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Wieprecht T, Seelig J. Isothermal titration calorimetry for studying interactions between peptides and lipid membranes. CURRENT TOPICS IN MEMBRANES 2002. [DOI: 10.1016/s1063-5823(02)52004-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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21
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Paquet MJ, Laviolette M, Pézolet M, Auger M. Two-dimensional infrared correlation spectroscopy study of the aggregation of cytochrome c in the presence of dimyristoylphosphatidylglycerol. Biophys J 2001; 81:305-12. [PMID: 11423415 PMCID: PMC1301512 DOI: 10.1016/s0006-3495(01)75700-1] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Two-dimensional infrared correlation spectroscopy (2D-IR) was used in this study to investigate the aggregation of cytochrome c in the presence of dimyristoylphosphatidylglycerol. The influence of temperature on the aggregation has been evaluated by monitoring the intensity of a band at 1616 cm(-1), which is characteristic of aggregated proteins, and the 2D-IR analysis has been used to determine the various secondary structure components of cytochrome c involved before and during its aggregation. The 2D-IR correlation analysis clearly reveals for the first time that aggregation starts to occur between nearly native proteins, which then unfold, yielding to further aggregation of the protein. Later in the aggregation process, the formation of intermolecular bonds and unfolding of the alpha-helices appear to be simultaneous. These results lead us to propose a two-step aggregation process. Finally, the results obtained during the heating period clearly indicate that before the protein starts to aggregate, there is a loosening of the tertiary structure of cytochrome c, resulting in a decrease of the beta-sheet content and an increase of the amount of beta-turns. This study clearly demonstrates the potential of 2D-IR spectroscopy to investigate the aggregation of proteins and this technique could therefore be applied to other proteins such as those involved in fibrilogenesis.
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Affiliation(s)
- M J Paquet
- Département de chimie, Centre de Recherche en Sciences et Ingénierie des Macromolécules, Université Laval, Québec, Québec, Canada G1K 7P4
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22
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Loidl-Stahlhofen A, Eckert A, Hartmann T, Schöttner M. Solid-supported lipid membranes as a tool for determination of membrane affinity: high-throughput screening of a physicochemical parameter. J Pharm Sci 2001; 90:599-606. [PMID: 11288104 DOI: 10.1002/1520-6017(200105)90:5<599::aid-jps1016>3.0.co;2-n] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Quantification of membrane affinity is an important early screening step in modern drug design. However, current approaches using different lipid membrane models usually are time-consuming or show severe experimental drawbacks. In this paper we describe the use of solid-supported lipid membranes (TRANSIL) as a new tool for the determination of membrane affinity. Eighteen pharmaceuticals (neutrals, acids, and bases) have been analyzed for their lipophilicity at physiological pH in an automated setup; phase separation of lipid and aqueous phase can be achieved simply by a short low-speed centrifugation or filtration. The membrane affinity is then calculated by quantification of the total drug concentration and the amount of drug remaining in the aqueous phase after incubation with solid-supported lipid membranes. Lipophilicity parameters relying on solid-supported lipid membranes correlate well with octanol-water partition coefficients K(ow) for neutral organic compounds (range of log K(ow) = 1.5-5, n = 7, r = 0.93). Data acquisition with this lipid membrane model system is highly re-producible. Even in the case of ionizable drugs, where K(ow) tends to underestimate membrane affinity, the latter can be correctly quantified using solid-supported lipid membranes: data comparison shows good agreement of the presented approach with established but time-consuming standardized lipid/buffer systems. Solid-supported lipid membranes allow a fast and reliable quantification of membrane affinity, enabling high-throughput screening of this physicochemical parameter.
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23
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Heerklotz H, Seelig J. Titration calorimetry of surfactant-membrane partitioning and membrane solubilization. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1508:69-85. [PMID: 11090819 DOI: 10.1016/s0304-4157(00)00009-5] [Citation(s) in RCA: 177] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The interaction of surfactants with membranes has been difficult to monitor since most detergents are small organic molecules without spectroscopic markers. The development of high sensitivity isothermal titration calorimetry (ITC) has changed this situation distinctly. The insertion of a detergent into the bilayer membrane is generally accompanied by a consumption or release of heat which can be measured fast and reliably with modern titration calorimeters. It is possible to determine the full set of thermodynamic parameters, i.e., the partitioning enthalpy, the partitioning isotherm, the partition coefficient, the free energy, and the entropy of transfer. The application of ITC to the following problems is described: (i) measurement of the critical micellar concentration (CMC) of pure detergent solutions; (ii) analysis of surfactant-membrane partitioning equilibria, including asymmetric insertion; and (iii) membrane-surfactant phase diagrams. Finally, the thermodynamic parameters derived for non-ionic detergents are discussed and the affinity for micelle formation is compared with membrane incorporation.
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Affiliation(s)
- H Heerklotz
- Department of Biophysical Chemistry, Biocenter of the University of Basel, Klingelbergstrasse 70, CH-4056, Basel, Switzerland
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24
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Stemp ED, Barton JK. The flash-quench technique in protein-DNA electron transfer: reduction of the guanine radical by ferrocytochrome c. Inorg Chem 2000; 39:3868-74. [PMID: 11196782 DOI: 10.1021/ic0000698] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Electron transfer from a protein to oxidatively damaged DNA, specifically from ferrocytochrome c to the guanine radical, was examined using the flash-quench technique. Ru(phen)2dppz2+ (dppz = dipyridophenazine) was employed as the photosensitive intercalator, and ferricytochrome c (Fe3+ cyt c), as the oxidative quencher. Using transient absorption and time-resolved luminescence spectroscopies, we examined the electron-transfer reactions following photoexcitation of the ruthenium complex in the presence of poly(dA-dT) or poly(dG-dC). The luminescence-quenching titrations of excited Ru(phen)2dppz2+ by Fe3+ cyt c are nearly identical for the two DNA polymers. However, the spectral characteristics of the long-lived transient produced by the quenching depend strongly upon the DNA. For poly(dA-dT), the transient has a spectrum consistent with formation of a [Ru(phen)2dppz3+, Fe2+ cyt c] intermediate, indicating that the system regenerates itself via electron transfer from the protein to the Ru(III) metallointercalator for this polymer. For poly(dG-dC), however, the transient has the characteristics expected for an intermediate of Fe2+ cyt c and the neutral guanine radical. The characteristics of the transient formed with the GC polymer are consistent with rapid oxidation of guanine by the Ru(III) complex, followed by slow electron transfer from Fe2+ cyt c to the guanine radical. These experiments show that electron holes on DNA can be repaired by protein and demonstrate how the flash-quench technique can be used generally in studying electron transfer from proteins to guanine radicals in duplex DNA.
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Affiliation(s)
- E D Stemp
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA
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25
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Sedlák E, Antalík M. Molten globule-like state of cytochrome c induced by polyanion poly(vinylsulfate) in slightly acidic pH. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1434:347-55. [PMID: 10525152 DOI: 10.1016/s0167-4838(99)00186-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The effect of polyanion, poly(vinylsulfate), used as a model of negatively charged surface, on ferric cytochrome c (ferricyt c) structure in acidic pH has been studied by absorbance spectroscopy, circular dichroism (CD), tryptophan (Trp) fluorescence and microcalorimetry. The polyanion induced only small changes in the native structure of the protein at neutral pH, but it profoundly shifted the acid induced high spin state of the heme in the active center of cyt c to a more neutral pH region. Cooperativity of the acidic transition of ferricyt c in the presence of the polyanion was disturbed, in comparison with uncomplexed protein, as followed from different apparent pK(a) values observed in a distinct regions of the ferricyt c electronic absorbance spectrum (4.55+/-0.08 in the 620 nm band region and 5.47+/-0.15 in the Soret region). The ferricyt c structure in the complex with the polyanion at acidic pH (below pH 5.0) has properties of a molten globule-like state. Its tertiary structure is strongly disturbed according to CD and microcalorimetry measurements; however, its secondary structure, from CD, is still native-like and ferricyt c is in a compact state as evidenced by quenched Trp fluorescence. These findings are discussed in the context of the molten globule state of proteins induced on a negatively charged membrane surface under physiological conditions.
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Affiliation(s)
- E Sedlák
- Department of Biochemistry, Faculty of Science, P.J. Safárik University, Moyzesova 11, 041 54, Kosice, Slovak Republic
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26
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Gorbenko GP. Structure of cytochrome c complexes with phospholipids as revealed by resonance energy transfer. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1420:1-13. [PMID: 10446285 DOI: 10.1016/s0005-2736(99)00082-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Resonance energy transfer between a series of lipid-bound fluorescent probes as donors and the heme group of cytochrome c as acceptor has been used to obtain structural information on the protein complexes with model membranes, composed of phosphatidylcholine and cardiolipin. Analysis of experimental data in terms of the model of energy transfer in two-dimensional systems provides further evidence for preferential cytochrome c orientation with respect to the lipid bilayer and penetration of the protein into the membrane interior.
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Affiliation(s)
- G P Gorbenko
- Department of Physics and Technology, Kharkov State University, Svoboda Sq. 4, Kharkov 310077, Ukraine
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27
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Gorbenko GP. Resonance energy transfer study of hemoglobin and cytochrome c complexes with lipids. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1409:12-24. [PMID: 9804870 DOI: 10.1016/s0005-2728(98)00140-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The complexes of hemoglobin and cytochrome c with liposomes composed of phosphatidylcholine and its mixtures with cardiolipin and cholesterol have been studied by monitoring resonance energy transfer between fluorescent probe 3-methoxybenzanthrone as donor and heme groups of the proteins as acceptors. By analyzing experimental data within the framework of the model of energy transfer in two-dimensional systems, the limits of the range of possible heme positions with respect to lipid bilayer have been assessed. The distance of heme group of hemoglobin from the membrane center was found to increase in the presence of cardiolipin or cholesterol. The results obtained for cytochrome c complexes with cardiolipin-containing model membranes suggest the existence of preferential protein orientation relative to the lipid bilayer, and provide evidence for the protein penetration in the membrane interior.
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Affiliation(s)
- G P Gorbenko
- Department of Physics and Technology, Kharkov State University, Tobolskaya Str. 52-52, 310077 Kharkov, Ukraine
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28
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Abstract
The properties of the complexes of ferricytochrome c with two different polyanions--poly(vinylsulfate) and poly(4-styrene-sulfonate)--with a comparable charge density but with the different size of the uncharged part of their molecules have been studied by means of optical spectroscopy, differential scanning colorimetry, and gel chromatography. Ferriccytochrome c formed a complex with the former one through coulombic interactions and remained in a native-like state. The addition of the second polyanion to a solution of ferric cytochrome c at a low ionic strength, pH 7.0, resulted in profound conformational change in the hydrophobic core of protein (opening of the heme crevice with a perturbation of the methionine 80-heme iron bond and the hydrophobic core of the protein). These may be understood as an involvement of noncoulombic (hydrophobic, H-bonding) interactions of the uncharged part of the polyanion molecule. Conformational changes and the observed shift in acidic transition from low spin to high spin state of ferric cytochrome c detected in the presence of the polyanions may have biological implication in understanding the origin of conformational changes in proteins induced in the course of their interaction with membrane lipids and membrane proteins.
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Affiliation(s)
- E Sedlák
- Department of Biochemistry, Faculty of Science, P. J. Safárik University, Kosice, Slovakia
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29
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Mancheño JM, Martínez del Pozo A, Albar JP, Oñaderra M, Gavilanes JG. A peptide of nine amino acid residues from alpha-sarcin cytotoxin is a membrane-perturbing structure. THE JOURNAL OF PEPTIDE RESEARCH : OFFICIAL JOURNAL OF THE AMERICAN PEPTIDE SOCIETY 1998; 51:142-8. [PMID: 9580217 DOI: 10.1111/j.1399-3011.1998.tb00632.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
A water-soluble synthetic peptide with only nine amino acid residues, comprising the 131-139 sequence region of the cytotoxic protein alpha-sarcin (secreted by the mold Aspergillus giganteus), interacts with large unilamellar vesicles composed of acid phospholipids. It promotes lipid mixing between bilayers and leakage of vesicle aqueous contents, and it also abolishes the phospholipid phase transition. Other larger peptides containing such an amino acid sequence also produce these effects. These peptides acquire alpha-helical conformation in the presence of trifluoroethanol, but display beta-strand conformation in the presence of sodium dodecyl sulfate. The interaction of these peptides with the lipid vesicles also results in beta-structure. The obtained data are discussed in terms of the involvement of the 131-139 stretch of alpha-sarcin in its interaction with lipid membranes.
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Affiliation(s)
- J M Mancheño
- Departamento de Bioquímica y Biología Molecular, Facultad de Química, Universidad Complutense, Madrid, Spain
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30
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Seelig J. Titration calorimetry of lipid-peptide interactions. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1331:103-16. [PMID: 9325437 DOI: 10.1016/s0304-4157(97)00002-6] [Citation(s) in RCA: 178] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- J Seelig
- Department of Biophysical Chemistry, University of Basel, Switzerland
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31
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Macromolecules in ordered media: 4. Poly(2-vinyl pyridine)-liposome association induced by electrostatic interactions. POLYMER 1997. [DOI: 10.1016/s0032-3861(96)00915-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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32
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Maier RJ. Respiratory metabolism in hyperthermophilic organisms: hydrogenases, sulfur reductases, and electron transport factors that function at temperatures exceeding 100 degrees C. ADVANCES IN PROTEIN CHEMISTRY 1996; 48:35-99. [PMID: 8791624 DOI: 10.1016/s0065-3233(08)60361-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- R J Maier
- Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218, USA
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33
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Gasset M, Mancheño JM, Laynez J, Lacadena J, Fernández-Ballester G, Martinez del Pozo A, Oñaderra M, Gavilanes JG. Thermal unfolding of the cytotoxin alpha-sarcin: phospholipid binding induces destabilization of the protein structure. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1252:126-34. [PMID: 7548154 DOI: 10.1016/0167-4838(95)00100-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The effect of membrane binding on the structure and stability of the cytotoxin alpha-sarcin has been studied by differential scanning calorimetry, Fourier-transform infrared and fluorescence spectroscopic techniques. The thermal unfolding of alpha-sarcin in aqueous solution fits into a two-state transition characterized by a transition temperature (Tm) of 52.6 degrees C and a calorimetric enthalpy (delta Hcal) of 136 kcal/mol. Upon interaction with phosphatidylglycerol vesicles, alpha-sarcin undergoes conformational changes, as deduced from the FTIR and fluorescence emission spectra. These changes result in a decreased Tm and delta Hcal values for the thermal unfolding of phospholipid-bound alpha-sarcin. The lower Tm value for lipid-bound alpha-sarcin is also observed at the level of secondary and tertiary structures, based on analyses of both the amide I' infrared spectrum and the tryptophan emission of the protein as a function of temperature, respectively. The results obtained indicate a protein destabilization promoted by the phospholipid interaction.
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Affiliation(s)
- M Gasset
- Departamento de Bioquímica y Biología Molecular, Facultad de Química, Universidad Complutense, Madrid, Spain
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