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Sun Y, Oseliero Filho PL, Song Y, Wang Z, Ji H, Oliveira CLP. The role of hydrophobic interactions in the molten globule state of globular protein modulated by surfactants. Colloids Surf B Biointerfaces 2023; 230:113490. [PMID: 37556880 DOI: 10.1016/j.colsurfb.2023.113490] [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: 04/26/2023] [Revised: 06/25/2023] [Accepted: 07/31/2023] [Indexed: 08/11/2023]
Abstract
In order to highlight the role of hydrophobic interactions in the molten globule (MG) state of globular protein modulated by surfactants, the interactions of bovine α-lactalbumin (α-LA) with alkyl trimethylammonium bromides (CnTAB, n = 10, 12, 14, and 16) have been studied by experimental and theoretical techniques. Isothermal titration calorimetry (ITC) showed that the enthalpy changes (ΔH) and area of the enthalpogram increased with increasing the chain length of CnTAB. The result of fluorescence, circular dichroism (CD) and 1H nuclear magnetic resonance (NMR) spectrum suggested that C10TAB and C12TAB unfolded α-LA partially, C14TAB reconstructed protein with a native-like secondary structure content, and C16TAB induced an MG state α-LA. The SAXS results confirmed that the tertiary structure of α-LA was disrupted by C16TAB forming an MG state complex with a micelle-like structure even at the surfactants concentrations below CMC. As indicated by MD results, the β-domain and unstructured region(s) were involved in the MG state α-LA modulated by CnTAB. This work not only provides molecular insights into the role of hydrophobic interactions in the MG state of a globular protein but also helps understand the mechanism of preparing α-LA based biomacromolecule modulated by hydrophobic interactions.
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Affiliation(s)
- Yang Sun
- College of Vocational and Technical Education, Yunnan Normal University, Kunming, Yunnan, China.
| | | | - Yang Song
- College of Vocational and Technical Education, Yunnan Normal University, Kunming, Yunnan, China
| | - Zhichun Wang
- College of Vocational and Technical Education, Yunnan Normal University, Kunming, Yunnan, China
| | - Hang Ji
- College of Vocational and Technical Education, Yunnan Normal University, Kunming, Yunnan, China
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2
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Sarkar P, Chattopadhyay A. Membrane Dipole Potential: An Emerging Approach to Explore Membrane Organization and Function. J Phys Chem B 2022; 126:4415-4430. [PMID: 35696090 DOI: 10.1021/acs.jpcb.2c02476] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Biological membranes are complex organized molecular assemblies of lipids and proteins that provide cells and membrane-bound intracellular organelles their individual identities by morphological compartmentalization. Membrane dipole potential originates from the electrostatic potential difference within the membrane due to the nonrandom arrangement (orientation) of amphiphile and solvent (water) dipoles at the membrane interface. In this Feature Article, we will focus on the measurement of dipole potential using electrochromic fluorescent probes and highlight interesting applications. In addition, we will focus on ratiometric fluorescence microscopic imaging technique to measure dipole potential in cellular membranes, a technique that can be used to address novel problems in cell biology which are otherwise difficult to address using available approaches. We envision that membrane dipole potential could turn out to be a convenient tool in exploring the complex interplay between membrane lipids and proteins and could provide novel insights in membrane organization and function.
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Affiliation(s)
- Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
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3
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Effect of Local Anesthetics on Dipole Potential of Different Phase Membranes: A Fluorescence Study. J Membr Biol 2022; 255:363-369. [PMID: 35587273 DOI: 10.1007/s00232-022-00240-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 04/22/2022] [Indexed: 12/17/2022]
Abstract
The molecular mechanism behind the action of local anesthetics is not well understood. Phenylethanol (PEtOH) is an ingredient of essential oils with a rose-like odor, and it has previously been used as a local anesthetic. In this work, we explored the effect of PEtOH on dipole potential in membranes representing biologically relevant phases, employing the dual-wavelength ratiometric method utilizing the potential-sensitive probe di-8-ANEPPS. Our results show that PEtOH reduces membrane dipole potential in membranes of all biologically relevant phases (gel, liquid-ordered, and fluid) in a concentration-dependent manner. To the best of our knowledge, these results constitute one of the early reports describing reduction of membrane dipole potential induced by local anesthetics, irrespective of membrane phase.
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4
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Impact of Synthesized AuNPs from Crocin Against Aggregation and Conformational Change in α-Lactalbumin. Int J Pept Res Ther 2021. [DOI: 10.1007/s10989-021-10252-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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5
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Identification and in silico characterization of structural and functional impacts of genetic variants in milk protein genes in the Zebu breeds Guzerat and Gyr. Trop Anim Health Prod 2021; 53:524. [PMID: 34705124 DOI: 10.1007/s11250-021-02970-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 10/14/2021] [Indexed: 10/20/2022]
Abstract
Whole genome sequencing of bovine breeds has allowed identification of genetic variants in milk protein genes. However, functional repercussion of such variants at a molecular level has seldom been investigated. Here, the results of a multistep Bioinformatic analysis for functional characterization of recently identified genetic variants in Brazilian Gyr and Guzerat breeds is described, including predicted effects on the following: (i) evolutionary conserved nucleotide positions/regions; (ii) protein function, stability, and interactions; (iii) splicing, branching, and miRNA binding sites; (iv) promoters and transcription factor binding sites; and (v) collocation with QTL. Seventy-one genetic variants were identified in the caseins (CSN1S1, CSN2, CSN1S2, and CSN3), LALBA, LGB, and LTF genes. Eleven potentially regulatory variants and two missense mutations were identified. LALBA Ile60Val was predicted to affect protein stability and flexibility, by reducing the number the disulfide bonds established. LTF Thr546Asn is predicted to generate steric clashes, which could mildly affect iron coordination. In addition, LALBA Ile60Val and LTF Thr546Asn affect exonic splicing enhancers and silencers. Consequently, both mutations have the potential of affecting immune response at individual level, not only in the mammary gland. Although laborious, this multistep procedure for classifying variants allowed the identification of potentially functional variants for milk protein genes.
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6
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Dashnaw CM, Koone JC, Abdolvahabi A, Shaw BF. Measuring how two proteins affect each other's net charge in a crowded environment. Protein Sci 2021; 30:1594-1605. [PMID: 33928693 DOI: 10.1002/pro.4092] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 04/23/2021] [Indexed: 12/19/2022]
Abstract
Theory predicts that the net charge (Z) of a protein can be altered by the net charge of a neighboring protein as the two approach one another below the Debye length. This type of charge regulation suggests that a protein's charge and perhaps function might be affected by neighboring proteins without direct binding. Charge regulation during protein crowding has never been directly measured due to analytical challenges. Here, we show that lysine specific protein crosslinkers (NHS ester-Staudinger pairs) can be used to mimic crowding by linking two non-interacting proteins at a maximal distance of ~7.9 Å. The net charge of the regioisomeric dimers and preceding monomers can then be determined with lysine-acyl "protein charge ladders" and capillary electrophoresis. As a proof of concept, we covalently linked myoglobin (Zmonomer = -0.43 ± 0.01) and α-lactalbumin (Zmonomer = -4.63 ± 0.05). Amide hydrogen/deuterium exchange and circular dichroism spectroscopy demonstrated that crosslinking did not significantly alter the structure of either protein or result in direct binding (thus mimicking crowding). Ultimately, capillary electrophoretic analysis of the dimeric charge ladder detected a change in charge of ΔZ = -0.04 ± 0.09 upon crowding by this pair (Zdimer = -5.10 ± 0.07). These small values of ΔZ are not necessarily general to protein crowding (qualitatively or quantitatively) but will vary per protein size, charge, and solvent conditions.
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Affiliation(s)
- Chad M Dashnaw
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas, USA
| | - Jordan C Koone
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas, USA
| | - Alireza Abdolvahabi
- Mass Spectrometry Core Facility, School of Pharmacy, University of Southern California, Los Angeles, California, USA
| | - Bryan F Shaw
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas, USA
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7
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α-Lactalbumin, Amazing Calcium-Binding Protein. Biomolecules 2020; 10:biom10091210. [PMID: 32825311 PMCID: PMC7565966 DOI: 10.3390/biom10091210] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 08/14/2020] [Accepted: 08/17/2020] [Indexed: 02/06/2023] Open
Abstract
α-Lactalbumin (α-LA) is a small (Mr 14,200), acidic (pI 4–5), Ca2+-binding protein. α-LA is a regulatory component of lactose synthase enzyme system functioning in the lactating mammary gland. The protein possesses a single strong Ca2+-binding site, which can also bind Mg2+, Mn2+, Na+, K+, and some other metal cations. It contains several distinct Zn2+-binding sites. Physical properties of α-LA strongly depend on the occupation of its metal binding sites by metal ions. In the absence of bound metal ions, α-LA is in the molten globule-like state. The binding of metal ions, and especially of Ca2+, increases stability of α-LA against the action of heat, various denaturing agents and proteases, while the binding of Zn2+ to the Ca2+-loaded protein decreases its stability and causes its aggregation. At pH 2, the protein is in the classical molten globule state. α-LA can associate with membranes at neutral or slightly acidic pH at physiological temperatures. Depending on external conditions, α-LA can form amyloid fibrils, amorphous aggregates, nanoparticles, and nanotubes. Some of these aggregated states of α-LA can be used in practical applications such as drug delivery to tissues and organs. α-LA and some of its fragments possess bactericidal and antiviral activities. Complexes of partially unfolded α-LA with oleic acid are cytotoxic to various tumor and bacterial cells. α-LA in the cytotoxic complexes plays a role of a delivery carrier of cytotoxic fatty acid molecules into tumor and bacterial cells across the cell membrane. Perhaps in the future the complexes of α-LA with oleic acid will be used for development of new anti-cancer drugs.
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8
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Raina N, Singh AK, Hassan MI, Ahmad F, Islam A. Concentration dependent effect of ethylene glycol on the structure and stability of holo α-lactalbumin: Characterization of intermediate state amidst soft interactions. Int J Biol Macromol 2020; 164:2151-2161. [PMID: 32735932 DOI: 10.1016/j.ijbiomac.2020.07.224] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 07/22/2020] [Accepted: 07/24/2020] [Indexed: 12/16/2022]
Abstract
The interior of the cell is crowded with different kinds of biological molecules with varying sizes, shapes and compositions which may affect physiological processes especially protein folding, protein conformation and protein stability. To understand the consequences of such a crowded environment, pH-induced unfolding of holo alpha-lactalbumin (holo α-LA) was studied in the presence of ethylene glycol (EG). The effect of EG on the folding and stability of holo α-LA in aqueous solution was investigated using several spectroscopic techniques. The results indicate that stabilization/destabilization of holo α-LA by EG is concentration- and pH-dependent. Low concentration of EG stabilizes the protein at pH near its pI. From the results of far-UV CD, UV-visible and ANS fluorescence, intermediate state (MG state) was characterized in the presence of high concentration of ethylene glycol. The results invoke a new mechanism for the formation of MG state identical to active component of BAMLET. MG state of holo α-LA has a direct implication to cancer therapy. MG state of α-LA in complex with specific type of lipid is a novel class of protein-based anti-cancer complexes that incorporate oleic acid and deliver it to the cancer cells.
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Affiliation(s)
- Neha Raina
- Department of Biotechnology, Sharda University, Greater Noida, Uttar Pradesh 201310, India; Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi 110025, India
| | - Amit Kumar Singh
- Department of Biotechnology, Sharda University, Greater Noida, Uttar Pradesh 201310, India.
| | - Md Imtaiyaz Hassan
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi 110025, India
| | - Faizan Ahmad
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi 110025, India
| | - Asimul Islam
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi 110025, India.
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9
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Rao BD, Chakraborty H, Chaudhuri A, Chattopadhyay A. Differential sensitivity of pHLIP to ester and ether lipids. Chem Phys Lipids 2019; 226:104849. [PMID: 31836521 DOI: 10.1016/j.chemphyslip.2019.104849] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 12/05/2019] [Accepted: 12/05/2019] [Indexed: 10/25/2022]
Abstract
pH (low) insertion peptide (pHLIP) is a polypeptide from the third transmembrane helix of bacteriorhodopsin. The pH-dependent membrane insertion of pHLIP has been conveniently exploited for translocation of cargo molecules and as a novel imaging agent in cancer biology due to low extracellular pH in cancer tissues. Although the application of pHLIP for imaging tumor and targeted drug delivery is well studied, literature on pHLIP-membrane interaction is relatively less studied. Keeping this in mind, we explored the differential interaction of pHLIP with ester and ether lipid membranes utilizing fluorescence and CD spectroscopy. We report, for the first time, higher binding affinity of pHLIP toward ether lipid relative to ester lipid membranes. There results gain relevance since Halobacterium halobium (source of bacteriorhodopsin) is enriched with ether lipids. In addition, we monitored the difference in microenvironment around pHLIP tryptophans utilizing red edge excitation shift and observed increased motional restriction of water molecules in the interfacial region in ether lipid membranes. These changes were accompanied with increase in helicity of pHLIP in ether lipid relative to ester lipid membranes. Our results assume further relevance since ether lipids are upregulated in cancer cells and have emerged as potential biomarkers of various diseases including cancer.
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Affiliation(s)
- Bhagyashree D Rao
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500 007, India; CSIR-Indian Institute of Chemical Technology, Uppal Road, Hyderabad, 500 007, India; Academy of Scientific and Innovative Research, Ghaziabad, 201 002, India
| | - Hirak Chakraborty
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500 007, India; School of Chemistry, Sambalpur University, Jyoti Vihar, Burla, Odisha, 768 019, India
| | - Arunima Chaudhuri
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500 007, India
| | - Amitabha Chattopadhyay
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500 007, India; Academy of Scientific and Innovative Research, Ghaziabad, 201 002, India.
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10
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Radibratovic M, Al-Hanish A, Minic S, Radomirovic M, Milcic M, Stanic-Vucinic D, Cirkovic Velickovic T. Stabilization of apo α-lactalbumin by binding of epigallocatechin-3-gallate: Experimental and molecular dynamics study. Food Chem 2019; 278:388-395. [DOI: 10.1016/j.foodchem.2018.11.038] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 11/01/2018] [Accepted: 11/06/2018] [Indexed: 10/27/2022]
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11
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Cytotoxicity of apo bovine α-lactalbumin complexed with La 3+ on cancer cells supported by its high resolution crystal structure. Sci Rep 2019; 9:1780. [PMID: 30741951 PMCID: PMC6370903 DOI: 10.1038/s41598-018-38024-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 12/11/2018] [Indexed: 11/08/2022] Open
Abstract
Cancer remains one of the biggest threats to human society. There are massive demands for compounds to selectively kill cancerous cells. Earlier studies have shown that bovine α -lactalbumin made lethal to tumor cells (BAMLET) becomes cytotoxic against cancer cells in complex with oleic acid {Hoque, M. et. al., PLoSOne8, e68390 (2013)}. In our study, we obtained bovine α-lactalbumin complexed with lanthanum ion (La3+-B-α-LA) and determined its high resolution crystal structure. The natural calcium binding site of bovine α-lactalbumin is replaced by lanthanum. The La3+ complex formation by B-α-apo-LA was also supported by various biophysical methods. Interestingly, our complex, La3+-B-α-LA exhibits much greater anticancer activity against breast cancer cells as compared to the reported BAMLET-oleic acid complex. This study shows that La3+-B-α-LA complex is preferentially more toxic to MCF-7 cells as compared to KB (oral cancer) and HeLa (cervical) cells, while almost non-toxic to the healthy cells that we studied. Our data indicates that the cytotoxicity of La3+-B-α-LA against cancer cells is through apoptotic path way. The higher anticancer activity of La3+-B-α-LA is attributable to the requisite structural changes induced in the protein by La3+ binding as supported by the crystal structure of the complex.
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12
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Rao E, Foderà V, Leone M, Vetri V. Direct observation of alpha-lactalbumin, adsorption and incorporation into lipid membrane and formation of lipid/protein hybrid structures. Biochim Biophys Acta Gen Subj 2019; 1863:784-794. [PMID: 30742952 DOI: 10.1016/j.bbagen.2019.02.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 02/06/2019] [Accepted: 02/07/2019] [Indexed: 02/02/2023]
Abstract
The interaction between proteins and membranes is of great interest in biomedical and biotechnological research for its implication in many functional and dysfunctional processes. We present an experimental study on the interaction between model membranes and alpha-lactalbumin (α-La). α-La is widely studied for both its biological function and its anti-tumoral properties. We use advanced fluorescence microscopy and spectroscopy techniques to characterize α-La-membrane mechanisms of interaction and α-La-induced modifications of membranes when insertion of partially disordered regions of protein chains in the lipid bilayer is favored. Moreover, using fluorescence lifetime imaging, we are able to distinguish between protein adsorption and insertion in the membranes. Our results indicate that, upon addition of α-La to giant vesicles samples, protein is inserted into the lipid bilayer with rates that are concentration-dependent. The formation of heterogeneous hybrid protein-lipid co-aggregates, paralleled with protein conformational and structural changes, alters the membrane structure and morphology, leading to an increase in membrane fluidity.
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Affiliation(s)
- Estella Rao
- Dipartimento di Fisica e Chimica, Università di Palermo, 90128 Palermo, Italy
| | - Vito Foderà
- Department of Pharmacy, Universitetsparken 2, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Maurizio Leone
- Dipartimento di Fisica e Chimica, Università di Palermo, 90128 Palermo, Italy
| | - Valeria Vetri
- Dipartimento di Fisica e Chimica, Università di Palermo, 90128 Palermo, Italy.
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13
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Keller RCA. Identification of Possible Lipid Binding Regions in Food Proteins and Peptides and Additional In Silico Analysis. FOOD BIOPHYS 2018. [DOI: 10.1007/s11483-018-9519-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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14
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Thombare VJ, Holden JA, Pal S, Reynolds EC, Chattopadhyay A, O'Brien-Simpson NM, Hutton CA. Antimicrobial activity of simplified mimics of celogentin C. Tetrahedron 2018. [DOI: 10.1016/j.tet.2017.12.032] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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15
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Solubilization of the serotonin 1A receptor monitored utilizing membrane dipole potential. Chem Phys Lipids 2017; 209:54-60. [DOI: 10.1016/j.chemphyslip.2017.10.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 10/02/2017] [Accepted: 10/02/2017] [Indexed: 12/31/2022]
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16
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Differential Membrane Dipolar Orientation Induced by Acute and Chronic Cholesterol Depletion. Sci Rep 2017; 7:4484. [PMID: 28667339 PMCID: PMC5493612 DOI: 10.1038/s41598-017-04769-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 05/22/2017] [Indexed: 02/02/2023] Open
Abstract
Cholesterol plays a crucial role in cell membrane organization, dynamics and function. Depletion of cholesterol represents a popular approach to explore cholesterol-sensitivity of membrane proteins. An emerging body of literature shows that the consequence of membrane cholesterol depletion often depends on the actual process (acute or chronic), although the molecular mechanism underlying the difference is not clear. Acute depletion, using cyclodextrin-type carriers, is faster relative to chronic depletion, in which inhibitors of cholesterol biosynthesis are used. With the overall goal of addressing molecular differences underlying these processes, we monitored membrane dipole potential under conditions of acute and chronic cholesterol depletion in CHO-K1 cells, using a voltage-sensitive fluorescent dye in dual wavelength ratiometric mode. Our results show that the observed membrane dipole potential exhibits difference under acute and chronic cholesterol depletion conditions, even when cholesterol content was identical. To the best of our knowledge, these results provide, for the first time, molecular insight highlighting differences in dipolar reorganization in these processes. A comprehensive understanding of processes in which membrane cholesterol gets modulated would provide novel insight in its interaction with membrane proteins and receptors, thereby allowing us to understand the role of cholesterol in cellular physiology associated with health and disease.
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17
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Mohammadi F, Moeeni M. Investigation of the binding interactions of Bisdemethoxycurcumin, Diacetylcurcumin and Diacetylbisdemethoxycurcumin with bovine α-lactalbumin by experimental and theoretical analysis. J Biomol Struct Dyn 2016; 35:3486-3498. [DOI: 10.1080/07391102.2016.1259588] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Fakhrossadat Mohammadi
- Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), Gava Zang, Zanjan 45137-66731, Iran
| | - Marzieh Moeeni
- Department of Chemistry, Institute for Advanced Studies in Basic Sciences (IASBS), Gava Zang, Zanjan 45137-66731, Iran
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18
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Sethy D, Chakraborty H. Micellar dipolar rearrangement is sensitive to hydrophobic chain length: Implication for structural switchover of piroxicam. Chem Phys Lipids 2016; 200:120-125. [PMID: 27680423 DOI: 10.1016/j.chemphyslip.2016.09.001] [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: 08/17/2016] [Revised: 09/06/2016] [Accepted: 09/21/2016] [Indexed: 10/21/2022]
Abstract
The interfacial properties of the membrane are exceptionally vital in drug-membrane interaction. They not only select out a particular prototropic form of the drug molecule for incorporation, but are also potent enough to induce structural switchover of these drugs in several cases. In this work, we quantitatively monitored the change in dipolar rearrangement of the micellar interface (as a simplified membrane mimic) by measuring the dielectric constant and dipole potential with the micellization of SDS at pH 3.6. The dielectric constant and dipole potential were measured utilizing the fluorescence of polarity sensitive probe, pyrene and potential-sensitive probe, di-8-ANEPPS, respectively. Our study demonstrates that the change in dipolar rearrangement directly influences the switchover equilibrium between the anionic and neutral from of piroxicam. We have further extended our work to evaluate the effect of hydrophobic chain length of the surfactants on the dipolar rearrangement and its effect on the structural switchover of piroxicam. It is interesting that the extent of switchover of piroxicam is directly correlated with the dipolar rearrangement induced bythe varying hydrophobic chain length of the surfactants. To the best of our knowledge, our results constitute the first report to show the dependence of dipole potential on the hydrophobic chain length of the surfactant and demonstrate that the dipolar rearrangement directly tunes the extent of structural switchover of piroxicam, which was so far only intuitive. We consider that this new finding would have promising implication in drug distribution and drug efficacy.
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Affiliation(s)
- Dasaratha Sethy
- School of Chemistry, Sambalpur University, Burla, Odisha 768 019, India
| | - Hirak Chakraborty
- School of Chemistry, Sambalpur University, Burla, Odisha 768 019, India.
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19
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Chaudhuri A, Prasanna X, Agiru P, Chakraborty H, Rydström A, Ho JCS, Svanborg C, Sengupta D, Chattopadhyay A. Protein-dependent Membrane Interaction of A Partially Disordered Protein Complex with Oleic Acid: Implications for Cancer Lipidomics. Sci Rep 2016; 6:35015. [PMID: 27731329 PMCID: PMC5059734 DOI: 10.1038/srep35015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 09/09/2016] [Indexed: 12/18/2022] Open
Abstract
Bovine α-lactalbumin (BLA) forms cytotoxic complexes with oleic acid (OA) that perturbs tumor cell membranes, but molecular determinants of these membrane-interactions remain poorly understood. Here, we aim to obtain molecular insights into the interaction of BLA/BLA-OA complex with model membranes. We characterized the folding state of BLA-OA complex using tryptophan fluorescence and resolved residue-specific interactions of BLA with OA using molecular dynamics simulation. We integrated membrane-binding data using a voltage-sensitive probe and molecular dynamics (MD) to demonstrate the preferential interaction of the BLA-OA complex with negatively charged membranes. We identified amino acid residues of BLA and BLA-OA complex as determinants of these membrane interactions using MD, functionally corroborated by uptake of the corresponding α-LA peptides across tumor cell membranes. The results suggest that the α-LA component of these cytotoxic complexes confers specificity for tumor cell membranes through protein interactions that are maintained even in the lipid complex, in the presence of OA.
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Affiliation(s)
- Arunima Chaudhuri
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | | | - Priyanka Agiru
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Hirak Chakraborty
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Anna Rydström
- Department of Microbiology, Immunology and Glycobiology (MIG), Institute of Laboratory Medicine, Lund University, Lund, Sweden
| | - James C. S. Ho
- Centre for Biomimetic Sensor Science, School of Materials Science & Engineering, Nanyang Technological University, 637553 Singapore
| | - Catharina Svanborg
- Department of Microbiology, Immunology and Glycobiology (MIG), Institute of Laboratory Medicine, Lund University, Lund, Sweden
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Liebau J, Pettersson P, Szpryngiel S, Mäler L. Membrane Interaction of the Glycosyltransferase WaaG. Biophys J 2016; 109:552-63. [PMID: 26244737 DOI: 10.1016/j.bpj.2015.06.036] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Revised: 06/17/2015] [Accepted: 06/19/2015] [Indexed: 11/30/2022] Open
Abstract
The glycosyltransferase WaaG is involved in the synthesis of lipopolysaccharides that constitute the outer leaflet of the outer membrane in Gram-negative bacteria such as Escherichia coli. WaaG has been identified as a potential antibiotic target, and inhibitor scaffolds have previously been investigated. WaaG is located at the cytosolic side of the inner membrane, where the enzyme catalyzes the transfer of the first outer-core glucose to the inner core of nascent lipopolysaccharides. Here, we characterized the binding of WaaG to membrane models designed to mimic the inner membrane of E. coli. Based on the crystal structure, we identified an exposed and largely α-helical 30-residue sequence, with a net positive charge and several aromatic amino acids, as a putative membrane-interacting region of WaaG (MIR-WaaG). We studied the peptide corresponding to this sequence, along with its bilayer interactions, using circular dichroism, fluorescence quenching, fluorescence anisotropy, and NMR. In the presence of dodecylphosphocholine, MIR-WaaG was observed to adopt a three-dimensional structure remarkably similar to the segment in the crystal structure. We found that the membrane interaction of WaaG is conferred at least in part by MIR-WaaG and that electrostatic interactions play a key role in binding. Moreover, we propose a mechanism of anchoring WaaG to the inner membrane of E. coli, where the central part of MIR-WaaG inserts into one leaflet of the bilayer. In this model, electrostatic interactions as well as surface-exposed Tyr residues bind WaaG to the membrane.
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Affiliation(s)
- Jobst Liebau
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Pontus Pettersson
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Scarlett Szpryngiel
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Lena Mäler
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden.
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Sarkar P, Chattopadhyay A. Micellar dipole potential is sensitive to sphere-to-rod transition. Chem Phys Lipids 2015; 195:34-8. [PMID: 26616562 DOI: 10.1016/j.chemphyslip.2015.11.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Revised: 11/16/2015] [Accepted: 11/17/2015] [Indexed: 12/31/2022]
Abstract
Structural transitions involving shape changes play an important role in cellular physiology. Charged micelles offer a convenient model system in which structural transitions can be suitably induced by increasing the ionic strength of the medium. In this paper, we have explored sphere-to-rod transition in charged micelles of SDS and CTAB by monitoring micellar dipole potential using the dual wavelength ratiometric approach utilizing the potential-sensitive membrane probe di-8-ANEPPS. Our results show that micellar dipole potential is sensitive to sphere-to-rod transition in charged micelles. Micellar dipole potential exhibited increase with increasing ionic strength (salt), irrespective of the nature of micellar charge, implying considerable dipolar reorganization underlying structural transitions. We interpret the increase in dipole potential due to sphere-to-rod transition because of an increase in the population of confined (nonrandom) dipoles induced by micellar organizational change. This is due to the fact that dipole potential arises due to the nonrandom arrangement of micellar dipoles and water molecules at the micelle interface. Our results constitute one of the first reports describing drastic dipolar reorganization due to micellar shape (and size) change. We envision that dipole potential measurements could provide novel insights into micellar processes that are associated with dipolar reorganization.
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Affiliation(s)
- Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
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Dipolar rearrangement during micellization explored using a potential-sensitive fluorescent probe. Chem Phys Lipids 2015; 191:91-5. [PMID: 26327331 DOI: 10.1016/j.chemphyslip.2015.08.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2015] [Revised: 08/22/2015] [Accepted: 08/24/2015] [Indexed: 02/07/2023]
Abstract
Dipole potential is the potential difference within the membrane bilayer, which originates due to the nonrandom arrangement of lipid dipoles and water molecules at the membrane interface. Although dipole potential is generally used in the context of bilayer membranes, the nonrandom arrangement of amphiphiles and water dipoles would also contribute to dipole potential in organized molecular assemblies such as micelles. In this work, we show that the process of micelle formation from monomers for a representative variety of detergents is associated with dipolar rearrangement. We monitor the dipolar reorganization upon micellization as a change in dipole potential, measured by the dual wavelength ratiometric approach utilizing the potential-sensitive membrane probe di-8-ANEPPS. We further utilized this phenomenon to estimate the critical micelle concentration (CMC) of a variety of detergents. CMC determined by this method are in overall agreement with the literature values of CMC for these detergents. To the best of our knowledge, these results constitute the first report showing dipolar reorientation during micellization. We conclude that dipole potential measurements could provide a novel approach to explore micellar organization.
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Mohammadi F, Moeeni M. Study on the interactions of trans-resveratrol and curcumin with bovine α-lactalbumin by spectroscopic analysis and molecular docking. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2015; 50:358-66. [DOI: 10.1016/j.msec.2015.02.007] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2014] [Revised: 01/18/2015] [Accepted: 02/07/2015] [Indexed: 01/26/2023]
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Chaturvedi D, Mahalakshmi R. Juxtamembrane tryptophans have distinct roles in defining the OmpX barrel-micelle boundary and facilitating protein-micelle association. FEBS Lett 2015; 588:4464-71. [PMID: 25448987 DOI: 10.1016/j.febslet.2014.10.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Revised: 10/15/2014] [Accepted: 10/16/2014] [Indexed: 10/24/2022]
Abstract
Defining the span of the transmembrane region, a key requirement to ensure correct folding, stability and function of bacterial outer membrane β-barrels, is assisted by the amphipathic property of tryptophan. We demonstrate the unique and distinctive properties of the interface Trp76 and Trp140 of outer membrane protein X, and map their positional relevance to the refolding process, barrel formation and the resulting stability in dodecylphosphocholine micelles. The solvent-exposed Trp76 displays a rigid interfacial localization, whereas Trp140 is relatively micelle-solvated and contributes to barrel folding and global OmpX stability. Kinetic contribution to OmpX stability is influenced by the two tryptophans. Differential associations of the indoles with the detergent milieu therefore contribute to micelle-assisted β-barrel folding and concomitant OmpX stability.
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Affiliation(s)
- Deepti Chaturvedi
- Molecular Biophysics Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal 462023, India
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25
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Analysis of binding interaction of genistein and kaempferol with bovine α-lactalbumin. J Funct Foods 2015. [DOI: 10.1016/j.jff.2014.12.012] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Abdelhamid HN, Wu HF. Synthesis of a highly dispersive sinapinic acid@graphene oxide (SA@GO) and its applications as a novel surface assisted laser desorption/ionization mass spectrometry for proteomics and pathogenic bacteria biosensing. Analyst 2015; 140:1555-65. [DOI: 10.1039/c4an02158d] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
GO-modified sinapinic acid was synthesized and characterized; it was then investigated for use in SALDI-MS for proteomics and pathogenic bacterial biosensing.
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Affiliation(s)
- Hani Nasser Abdelhamid
- Department of Chemistry
- National Sun Yat-Sen University
- Kaohsiung
- Taiwan
- Department of Chemistry
| | - Hui-Fen Wu
- Department of Chemistry
- National Sun Yat-Sen University
- Kaohsiung
- Taiwan
- School of Pharmacy
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Bandari S, Chakraborty H, Covey DF, Chattopadhyay A. Membrane dipole potential is sensitive to cholesterol stereospecificity: implications for receptor function. Chem Phys Lipids 2014; 184:25-9. [PMID: 25219773 DOI: 10.1016/j.chemphyslip.2014.09.001] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 09/05/2014] [Accepted: 09/08/2014] [Indexed: 12/25/2022]
Abstract
Dipole potential is the potential difference within the membrane bilayer, which originates due to the nonrandom arrangement of lipid dipoles and water molecules at the membrane interface. Cholesterol, an essential lipid in higher eukaryotic membranes, has previously been shown to increase membrane dipole potential. In this work, we explored the effect of stereoisomers of cholesterol, ent-cholesterol and epi-cholesterol, on membrane dipole potential, monitored by the dual wavelength ratiometric approach utilizing the probe di-8-ANEPPS. Our results show that cholesterol and ent-cholesterol share comparable ability in increasing membrane dipole potential. In contrast, epi-cholesterol displays a slight reduction in membrane dipole potential. Our results constitute the first report on the effect of stereoisomers of cholesterol on membrane dipole potential, and imply that an extremely subtle change in sterol structure can significantly alter the dipolar field at the membrane interface. These results assume relevance in the context of differential abilities of these stereoisomers of cholesterol in supporting the activity of the serotonin1A receptor, a representative G protein-coupled receptor. The close correlation between membrane dipole potential and receptor activity provides new insight in receptor-cholesterol interaction in terms of stereospecificity. We envision that membrane dipole potential could prove to be a sensitive indicator of lipid-protein interactions in biological membranes.
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Affiliation(s)
- Suman Bandari
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Hirak Chakraborty
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Douglas F Covey
- Departments of Developmental Biology, Anesthesiology, Psychiatry and The Taylor Family Institute for Innovative Psychiatry Research, WA University in St. Louis Medical School, St. Louis, MO 63110, USA
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