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Rohlik DL, Patel E, Gilbert NC, Offenbacher AR, Garcia BL. Investigating membrane-binding properties of lipoxygenases using surface plasmon resonance. Biochem Biophys Res Commun 2023; 670:47-54. [PMID: 37276790 DOI: 10.1016/j.bbrc.2023.05.066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 05/18/2023] [Indexed: 06/07/2023]
Abstract
Lipoxygenases (LOXs) catalyze the oxidation of polyunsaturated fatty acids and synthesize oxylipin products that drive important cellular signaling processes in plants and animals. While there has been indirect evidence presented for the interaction of mammalian LOXs with membranes, a quantitative study of the molecular details of LOX-membrane interactions is lacking. Here, we mimicked biological membranes using surface plasmon resonance (SPR) sensor chips derivatized with 2-D planar lipophilic anchors (2D LP) to capture liposomes of varying phospholipid compositions that self-assemble into lipid bilayers on the SPR chip. The sensor chip surfaces were then used to investigate the membrane-binding properties of model LOX enzymes. SPR binding assays displayed reproducible and stable liposome capture to the sensor chip surface that allowed for the detailed characterization of LOX-membrane interactions. Our studies demonstrate a calcium-dependence for the membrane binding activities of coral 8R-LOX and human 15-LOX-2. Furthermore, our data confirm the importance of key membrane insertion loop residues in each of these LOX enzymes for membrane binding activity. Experiments utilizing model plant and human LOXs reveal differences in membrane-binding specificities. Our study establishes and validates a robust SPR-based platform using 2D LP sensor chips that allows for the detailed study of LOX-membrane interactions under different experimental conditions, including altered membrane compositions. Collectively, this investigation improves our overall understanding of LOX-membrane interaction properties, and our SPR-based approach holds potential for future use in the development of LOX-based therapeutics.
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Affiliation(s)
- Denise L Rohlik
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, NC, USA
| | - Ethan Patel
- Department Chemistry, East Carolina University, Greenville, NC, USA
| | - Nathaniel C Gilbert
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA
| | | | - Brandon L Garcia
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, NC, USA.
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2
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Zhu H, Zhang J, Dai X, Mesias VSD, Chi H, Wang C, Yeung CS, Chen Q, Liu W, Huang J. Tunable lipid-coated nanoporous silver sheet for characterization of protein-membrane interactions by surface-enhanced Raman scattering (SERS). Anal Bioanal Chem 2023:10.1007/s00216-023-04701-y. [PMID: 37083760 DOI: 10.1007/s00216-023-04701-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 03/14/2023] [Accepted: 04/12/2023] [Indexed: 04/22/2023]
Abstract
Membrane environments affect protein structures and functions through protein-membrane interactions in a wide range of important biological processes. To better study the effects from the lipid's hydrophilic and hydrophobic interaction with protein on different membrane regions, we developed the lipid-coated nanoporous silver sheets to provide tunable supported lipid monolayer/bilayer environments for in situ surface-enhanced Raman vibrational spectroscopy (SERS) characterizations. Under the controllable surface pressure, lipid monolayer/bilayer was coated along the microscopic curved surface of nanoporous silver sheets to serve as a cell membrane mimic as well as a barrier to avoid protein denaturation while empowering the high SERS enhancements from the underlying metallic bases allowing detection sensitivity at low physiological concentrations. Moreover, we fine-tuned the lipid packing density and controlled the orientation of the deposited lipid bilayers and monolayers to directly monitor the protein structures upon interactions with various membrane parts/positions. Our results indicate that lysozyme adopted the α-helical structure in both hydrophilic and hydrophobic interaction with lipid membrane. Interestingly, alpha-synuclein folded into the α-helical structure on the negatively charged lipid heads, whereas the hydrophobic lipid tails induced the β-sheet structural conversion of alpha-synuclein originated from its unstructured monomers. These direct observations on protein hydrophilic and hydrophobic interaction with lipid membrane might provide profound insights into the formation of the β-sheet-containing alpha-synuclein oligomers for further membrane disruptions and amyloid genesis associated with Parkinson's disease. Hence, with the controllability and tunability of lipid environments, our platform holds great promise for more general applications in investigating the influences from membranes and the correlative structures of proteins under both hydrophilic and hydrophobic effects.
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Affiliation(s)
- Hongni Zhu
- HKUST-Shenzhen Research Institute, No. 9 Yuexing First RD, Hi-Tech Park, Nanshan, , Shenzhen, 518057, China
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Jianing Zhang
- HKUST-Shenzhen Research Institute, No. 9 Yuexing First RD, Hi-Tech Park, Nanshan, , Shenzhen, 518057, China
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Xin Dai
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Vince St Dollente Mesias
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Huanyu Chi
- HKUST-Shenzhen Research Institute, No. 9 Yuexing First RD, Hi-Tech Park, Nanshan, , Shenzhen, 518057, China
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Congcheng Wang
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Chi Shun Yeung
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
- Department of Civil & Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong, China
| | - Qing Chen
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Wei Liu
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
| | - Jinqing Huang
- HKUST-Shenzhen Research Institute, No. 9 Yuexing First RD, Hi-Tech Park, Nanshan, , Shenzhen, 518057, China.
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
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Bondar AN, Barboiu M. Protons at bio-interfaces. Biochim Biophys Acta Biomembr 2023; 1865:184139. [PMID: 36775006 DOI: 10.1016/j.bbamem.2023.184139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 02/06/2023] [Indexed: 02/12/2023]
Affiliation(s)
- Ana-Nicoleta Bondar
- University of Bucharest, Faculty of Physics, Atomiștilor 405, Măgurele 077125, Romania; Forschungszentrum Jülich, Institute of Computational Biomedicine, IAS-5/INM-9, Wilhelm-Johnen Straße, 5428 Jülich, Germany.
| | - Mihail Barboiu
- Université de Montpelier, Institut Europeen de Membranes, Adaptive Supramolecular Nanosystems Group, ENSCM-CNRS, Place E. Bataillon CC047, 34095 Motpellier, France.
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Anselmo S, Sancataldo G, Foderà V, Vetri V. α-casein micelles-membranes interaction: Flower-like lipid protein coaggregates formation. Biochim Biophys Acta Gen Subj 2022; 1866:130196. [PMID: 35724888 DOI: 10.1016/j.bbagen.2022.130196] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 04/28/2022] [Accepted: 06/13/2022] [Indexed: 11/28/2022]
Abstract
BACKGROUND Environmental conditions regulate the association/aggregation states of proteins and their action in cellular compartments. Analysing protein behaviour in presence of lipid membranes is fundamental for the comprehension of many functional and dysfunctional processes. Here, we present an experimental study on the interaction between model membranes and α-casein. α-casein is the major component of milk proteins and it is recognised to play a key role in performing biological functions. The conformational properties of this protein and its capability to form supramolecular structures, like micelles or irreversible aggregates, are key effectors in functional and pathological effects. METHODS By means of quantitative fluorescence imaging and complementary spectroscopic methods, we were able to characterise α-casein association state and the course of events induced by pH changes, which regulate the interaction of this molecule with membranes. RESULTS The study of these complex dynamic events revealed that the initial conformation of the protein critically regulates the fate of α-casein, size and structure of the newly formed aggregates and their effect on membrane structures. Disassembly of micelles due to modification in electrostatic interactions results in increased membrane structure rigidity which accompanies the formation of protein lipid flower-like co-aggregates with protein molecules localised in the external part. GENERAL SIGNIFICANCE These results may contribute to the comprehension of how the initial state of a protein establishes the course of events that occur upon changes in the molecular environment. These events which may occur in cells may be essential to functional, pathological or therapeutical properties specifically associated to casein proteins.
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Affiliation(s)
- Sara Anselmo
- Dipartimento di Fisica e Chimica - Emilio Segré, Università degli Studi di Palermo, Viale delle Scienze ed. 18, 90128 Palermo, Italy
| | - Giuseppe Sancataldo
- Dipartimento di Fisica e Chimica - Emilio Segré, Università degli Studi di Palermo, Viale delle Scienze ed. 18, 90128 Palermo, Italy
| | - Vito Foderà
- Department of Pharmacy, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark
| | - Valeria Vetri
- Dipartimento di Fisica e Chimica - Emilio Segré, Università degli Studi di Palermo, Viale delle Scienze ed. 18, 90128 Palermo, Italy.
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Chiou PC, Hsu WW, Chang Y, Chen YF. Molecular packing of lipid membranes and action mechanisms of membrane-active peptides. Colloids Surf B Biointerfaces 2022; 213:112384. [PMID: 35151994 DOI: 10.1016/j.colsurfb.2022.112384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 01/25/2022] [Accepted: 01/29/2022] [Indexed: 10/19/2022]
Abstract
Biomembranes are involved in diverse cellular activities. How membranes and proteins interact in the activities might hinge on the former's physical characteristics, which in turn are influenced by packing of lipid molecules. Yet, the validity of this understanding and its mechanism are unclear. By varying chain saturation of membranes, we explored correlations between lipid packing and peptide-mediated membrane disruption for the antimicrobial peptide, melittin, and amyloidogenic peptide, β-amyloid (1-42). Remarkably, reducing molecular packing flexibility enhanced the membrane disruption, possibly due to a shift from membrane perforation to micellization. A theoretical analysis suggested the energetic basis of this shift. This mechanistically shows that a peptide's mechanism might be dictated not only by its intrinsic properties but also by physical characteristics of membranes.
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Affiliation(s)
- Pin-Chiuan Chiou
- Department of Chemical and Materials Engineering, National Central University, Taoyuan 32001, Taiwan
| | - Wen-Wei Hsu
- Department of Chemical and Materials Engineering, National Central University, Taoyuan 32001, Taiwan
| | - Yung Chang
- R&D Center for Membrane Technology and Department of Chemical Engineering, Chung Yuan Christian University, Jhong-Li, Taoyuan 320, Taiwan
| | - Yi-Fan Chen
- Department of Chemical and Materials Engineering, National Central University, Taoyuan 32001, Taiwan.
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Abstract
Over the last 25 years, the biology of membrane proteins, including the PFPs-membranes interactions is seeking attention for the development of successful drug molecules against a number of infectious diseases. Pore forming toxins (PFTs), the largest family of PFPs are considered as a group of virulence factors produced in a large number of pathogenic systems which include streptococcus, pneumonia, Staphylococcus aureus, E. coli, Mycobacterium tuberculosis, group A and B streptococci, Corynebacterium diphtheria and many more. PFTs are generally utilized by the disease causing pathogens to disrupt the host first line of defense i.e. host cell membranes through pore formation strategy. Although, pore formation is the principal mode of action of the PFTs but they can have additional adverse effects on the hosts including immune evasion. Recently, structural investigation of different PFTs have imparted the molecular mechanistic insights into how PFTs get transformed from its inactive state to active toxic state. On the basis of their structural entity, PFTs have been classified in different types and their mode of actions alters in terms of pore formation and corresponding cellular toxicity. Although pathogen genome analysis can identify the probable PFTs depending upon their structural diversity, there are so many PFTs which utilize the local environmental conditions to generate their pore forming ability using a novel strategy which is known as "conformational switch" of a protein. This conformational switch is considered as characteristics of the phase shifting proteins which were often utilized by many pathogenic systems to protect them from the invaders through allosteric communication between distant regions of the protein. In this chapter, we discuss the structure function relationships of PFTs and how activity of PFTs varies with the change in the environmental conditions has been explored. Finally, we demonstrate these structural insights to develop therapeutic potential to treat the infections caused by multidrug resistant pathogens.
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Affiliation(s)
- Achinta Sannigrahi
- Department of Chemical Engineering, Indian Institute of Science, Bengaluru, Karnataka, India.
| | - Krishnananda Chattopadhyay
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, West Bengal, India.
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Migliori AD, Patel LA, Neale C. The RIT1 C-terminus associates with lipid bilayers via charge complementarity. Comput Biol Chem 2021; 91:107437. [PMID: 33517146 DOI: 10.1016/j.compbiolchem.2021.107437] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 12/30/2020] [Accepted: 01/14/2021] [Indexed: 12/13/2022]
Abstract
RIT1 is a member of the Ras superfamily of small GTPases involved in regulation of cellular signaling. Mutations to RIT1 are involved in cancer and developmental disorders. Like many Ras subfamily members, RIT1 is localized to the plasma membrane. However, RIT1 lacks the C-terminal prenylation that helps many other subfamily members adhere to cellular membranes. We used molecular dynamics simulations to examine the mechanisms by which the C-terminal peptide (CTP) of RIT1 associates with lipid bilayers. We show that the CTP is unstructured and that its membrane interactions depend on lipid composition. While a 12-residue region of the CTP binds strongly to anionic bilayers containing phosphatidylserine lipids, the CTP termini fray from the membrane allowing for accommodation of the RIT1 globular domain at the membrane-water interface.
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Affiliation(s)
- Amy D Migliori
- Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM, 87545, United States; Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, NM, 87545, United States
| | - Lara A Patel
- Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM, 87545, United States; Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, NM, 87545, United States
| | - Chris Neale
- Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, NM, 87545, United States.
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8
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Larsen EK, Weber DK, Wang S, Gopinath T, Blackwell DJ, Dalton MP, Robia SL, Gao J, Veglia G. Intrinsically disordered HAX-1 regulates Ca 2+ cycling by interacting with lipid membranes and the phospholamban cytoplasmic region. Biochim Biophys Acta Biomembr 2020; 1862:183034. [PMID: 31400305 PMCID: PMC6899184 DOI: 10.1016/j.bbamem.2019.183034] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 07/09/2019] [Accepted: 07/30/2019] [Indexed: 01/14/2023]
Abstract
Hematopoietic-substrate-1 associated protein X-1 (HAX-1) is a 279 amino acid protein expressed ubiquitously. In cardiac muscle, HAX-1 was found to modulate the sarcoendoplasmic reticulum calcium ATPase (SERCA) by shifting its apparent Ca2+ affinity (pCa). It has been hypothesized that HAX-1 binds phospholamban (PLN), enhancing its inhibitory function on SERCA. HAX-1 effects are reversed by cAMP-dependent protein kinase A that phosphorylates PLN at Ser16. To date, the molecular mechanisms for HAX-1 regulation of the SERCA/PLN complex are still unknown. Using enzymatic, in cell assays, circular dichroism, and NMR spectroscopy, we found that in the absence of a binding partner HAX-1 is essentially disordered and adopts a partial secondary structure upon interaction with lipid membranes. Also, HAX-1 interacts with the cytoplasmic region of monomeric and pentameric PLN as detected by NMR and in cell FRET assays, respectively. We propose that the regulation of the SERCA/PLN complex by HAX-1 is mediated by its interactions with lipid membranes, adding another layer of control in Ca2+ homeostatic balance in the heart muscle.
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Affiliation(s)
- Erik K Larsen
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Daniel K Weber
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Songlin Wang
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Tata Gopinath
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | | | - Michael P Dalton
- Department of Physiology, Loyola University, Maywood, IL 60153, USA
| | - Seth L Robia
- Department of Physiology, Loyola University, Maywood, IL 60153, USA
| | - Jiali Gao
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA; School of Chemical Biology and Technology, Beijing University Graduate School, Shenzhen 518055, China
| | - Gianluigi Veglia
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA; Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.
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Dupuis JH, Yu H, Habibi M, Peng X, Plotkin SS, Wang S, Song C, Yada RY. pH dependent membrane binding of the Solanum tuberosum plant specific insert: An in silico study. Biochim Biophys Acta Biomembr 2018; 1860:2608-18. [PMID: 30291921 DOI: 10.1016/j.bbamem.2018.10.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 09/27/2018] [Accepted: 10/01/2018] [Indexed: 01/07/2023]
Abstract
The Solanum tuberosum plant-specific insert (StPSI) has been shown to possess potent antimicrobial activity against both human and plant pathogens. Furthermore, in vitro, the StPSI is capable of fusing phospholipid vesicles, provided the conditions of net anionic vesicle charge and acidic pH are met. Constant pH replica-exchange simulations indicate several acidic residues on the dimer have highly perturbed pKas (<3.0; E15, D28, E85 & E100) due to involvement in salt bridges. After setting the pH of the system to either 3.0 or 7.4, all-atom simulations provided details of the effect of pH on secondary structural elements, particularly in the previously unresolved crystallographic structure of the loop section. Coarse-grained dimer-bilayer simulations demonstrated that at pH 7.4, the dimer had no affinity for neutral or anionic membranes over the course of 1 μs simulations. Conversely, at pH 3.0 two binding modes were observed. Mode 1 is mediated primarily via strong N-terminal interactions on one monomer only, whereas in mode 2, N- and C-terminal residues of one monomer and numerous polar and basic residues on the second monomer, particularly in the third helix, participate in membrane interactions. Mode 2 was accompanied by re-orientation of the dimer to a more vertical position with respect to helices 1 and 4, positioning the dimer for membrane interactions. These results offer the first examination at near-atomic resolution of residues mediating the StPSI-membrane interactions, and allow for the postulation of a possible fusion mechanism.
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Schweitzer-Stenner R. Relating the multi-functionality of cytochrome c to membrane binding and structural conversion. Biophys Rev 2018; 10:1151-1185. [PMID: 29574621 PMCID: PMC6082307 DOI: 10.1007/s12551-018-0409-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 02/23/2018] [Indexed: 12/16/2022] Open
Abstract
Cytochrome c is known as an electron-carrying protein in the respiratory chain of mitochondria. Over the last 20 years, however, alternative functions of this very versatile protein have become the focus of research interests. Upon binding to anionic lipids such as cardiolipin, the protein acquires peroxidase activity. Multiple lines of evidence suggest that this requires a conformational change of the protein which involves partial unfolding of its tertiary structure. This review summarizes the current state of knowledge of how cytochrome c interacts with cardiolipin-containing surfaces and how this affects its structure and function. In this context, we delineate partially conflicting results regarding the affinity of cytochrome c binding to cardiolipin-containing liposomes of different size and its influence on the structure of the protein and the morphology of the membrane.
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Vázquez RF, Daza Millone MA, Pavinatto FJ, Herlax VS, Bakás LS, Oliveira ON, Vela ME, Maté SM. Interaction of acylated and unacylated forms of E. coli alpha-hemolysin with lipid monolayers: a PM-IRRAS study. Colloids Surf B Biointerfaces 2017; 158:76-83. [PMID: 28683345 DOI: 10.1016/j.colsurfb.2017.06.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 06/12/2017] [Accepted: 06/19/2017] [Indexed: 11/18/2022]
Abstract
Uropathogenic strains of Escherichia coli produce virulence factors, such as the protein toxin alpha-hemolysin (HlyA), that enable the bacteria to colonize the host and establish an infection. HlyA is synthetized as a protoxin (ProHlyA) that is transformed into the active form in the bacterial cytosol by the covalent linkage of two fatty-acyl moieties to the polypeptide chain before the secretion of HlyA into the extracellular medium. The aim of this work was to investigate the effect of the fatty acylation of HlyA on protein conformation and protein-membrane interactions. Polarization-modulated infrared reflection-absorption spectroscopy (PM-IRRAS) experiments were performed at the air-water interface, and lipid monolayers mimicking the outer leaflet of red-blood-cell membranes were used as model systems for the study of protein-membrane interaction. According to surface-pressure measurements, incorporation of the acylated protein into the lipid films was faster than that of the nonacylated form. PM-IRRAS measurements revealed that the adsorption of the proteins to the lipid monolayers induced disorder in the lipid acyl chains and also changed the elastic properties of the films independently of protein acylation. No significant difference was observed between HlyA and ProHlyA in the interaction with the model lipid monolayers; but when these proteins became adsorbed on a bare air-water interface, they adopted different secondary structures. The assumption of the correct protein conformation at a hydrophobic-hydrophilic interface could constitute a critical condition for biologic activity.
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Affiliation(s)
- Romina F Vázquez
- Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), CCT- La Plata, CONICET. Facultad de Ciencias Médicas. Universidad Nacional de La Plata, 60 y 120, 1900, La Plata, Argentina
| | - María A Daza Millone
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), CCT- La Plata, CONICET. Universidad Nacional de La Plata, Sucursal 4 Casilla de Correo 16, 1900, La Plata, Argentina
| | - Felippe J Pavinatto
- Instituto de Física de São Carlos (IFSC), Universidade de São Paulo, SP, Brazil
| | - Vanesa S Herlax
- Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), CCT- La Plata, CONICET. Facultad de Ciencias Médicas. Universidad Nacional de La Plata, 60 y 120, 1900, La Plata, Argentina
| | - Laura S Bakás
- Centro de Investigación de Proteínas Vegetales (CIPROVE), Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas. Universidad Nacional de La Plata. 47 y 115, 1900, La Plata, Argentina
| | - Osvaldo N Oliveira
- Instituto de Física de São Carlos (IFSC), Universidade de São Paulo, SP, Brazil
| | - María E Vela
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), CCT- La Plata, CONICET. Universidad Nacional de La Plata, Sucursal 4 Casilla de Correo 16, 1900, La Plata, Argentina
| | - Sabina M Maté
- Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), CCT- La Plata, CONICET. Facultad de Ciencias Médicas. Universidad Nacional de La Plata, 60 y 120, 1900, La Plata, Argentina.
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