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Bhat RAH, Khangembam VC, Pant V, Tandel RS, Pandey PK, Thakuria D. Antibacterial activity of a short de novo designed peptide against fish bacterial pathogens. Amino Acids 2024; 56:28. [PMID: 38578302 PMCID: PMC10997546 DOI: 10.1007/s00726-024-03388-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 03/06/2024] [Indexed: 04/06/2024]
Abstract
In the face of increasing antimicrobial resistance in aquaculture, researchers are exploring novel substitutes to customary antibiotics. One potential solution is the use of antimicrobial peptides (AMPs). We aimed to design and evaluate a novel, short, and compositionally simple AMP with potent activity against various bacterial pathogens in aquaculture. The resulting peptide, KK12YW, has an amphipathic nature and net charge of + 7. Molecular docking experiments disclosed that KK12YW has a strong affinity for aerolysin, a virulence protein produced by the bacterial pathogen Aeromonas sobria. KK12YW was synthesized using Fmoc chemistry and tested against a range of bacterial pathogens, including A. sobria, A. salmonicida, A. hydrophila, Edwardsiella tarda, Vibrio parahaemolyticus, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus epidermidis, and methicillin-resistant S. aureus. The AMP showed promising antibacterial activity, with MIC and MBC values ranging from 0.89 to 917.1 µgmL-1 and 3.67 to 1100.52 µgmL-1, respectively. In addition, KK12YW exhibited resistance to high temperatures and remained effective even in the presence of serum and salt, indicating its stability. The peptide also demonstrated minimal hemolysis toward fish RBCs, even at higher concentrations. Taken together, these findings indicate that KK12YW could be a highly promising and viable substitute for conventional antibiotics to combat microbial infections in aquaculture.
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Affiliation(s)
| | - Victoria C Khangembam
- ICAR-Directorate of Coldwater Fisheries Research, Bhimtal, 263136, Uttarakhand, India
| | - Vinita Pant
- ICAR-Directorate of Coldwater Fisheries Research, Bhimtal, 263136, Uttarakhand, India
| | - Ritesh Shantilal Tandel
- ICAR-Directorate of Coldwater Fisheries Research, Bhimtal, 263136, Uttarakhand, India
- Navsari Gujarat Research Centre, ICAR-Central Institute of Brackishwater Aquaculture, Navsari, 396 450, Gujarat, India
| | - Pramod Kumar Pandey
- ICAR-Directorate of Coldwater Fisheries Research, Bhimtal, 263136, Uttarakhand, India
| | - Dimpal Thakuria
- ICAR-Directorate of Coldwater Fisheries Research, Bhimtal, 263136, Uttarakhand, India.
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2
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Almeida PF. In Search of a Molecular View of Peptide-Lipid Interactions in Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023. [PMID: 37478368 DOI: 10.1021/acs.langmuir.3c00538] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/23/2023]
Abstract
Lipid bilayer membranes are often represented as a continuous nonpolar slab with a certain thickness bounded by two more polar interfaces. Phenomena such as peptide binding to the membrane surface, folding, insertion, translocation, and diffusion are typically interpreted on the basis of this view. In this Perspective, I argue that this membrane representation as a hydrophobic continuum solvent is not adequate to understand peptide-lipid interactions. Lipids are not small compared to membrane-active peptides: their sizes are similar. Therefore, peptide diffusion needs to be understood in terms of free volume, not classical continuum mechanics; peptide solubility or partitioning in membranes cannot be interpreted in terms of hydrophobic mismatch between membrane thickness and peptide length; peptide folding and translocation, often involving cationic peptides, can only be understood if realizing that lipids adapt to the presence of peptides and the membrane may undergo considerable lipid redistribution in the process. In all of those instances, the detailed molecular interactions between the peptide residues and the lipid components are essential to understand the mechanisms involved.
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Affiliation(s)
- Paulo F Almeida
- Department of Chemistry and Biochemistry, University of North Carolina Wilmington, Wilmington, North Carolina 28403, United States
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3
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Ishikawa R, Saito K, Misawa T, Demizu Y, Saito Y. Identification of the Stapled α-Helical Peptide ATSP-7041 as a Substrate and Strong Inhibitor of OATP1B1 In Vitro. Biomolecules 2023; 13:1002. [PMID: 37371582 DOI: 10.3390/biom13061002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 06/13/2023] [Accepted: 06/14/2023] [Indexed: 06/29/2023] Open
Abstract
ATSP-7041, a stapled α-helical peptide that inhibits murine double minute-2 (MDM2) and MDMX activities, is a promising modality targeting protein-protein interactions. As peptides of molecular weights over 1000 Da are not usually evaluated, data on the drug-drug interaction (DDI) potential of stapled α-helical peptides remain scarce. Here, we evaluate the interaction of ATSP-7041 with hepatic cytochrome P450s (CYPs; CYP1A2, CYP2C9, CYP2C19, CYP3A4, and CYP2D6) and transporters (organic anion transporting polypeptides (OATPs; OATP1B1 and OATP1B3), P-glycoprotein (P-gp), and breast cancer resistance protein (BCRP)). ATSP-7041 demonstrated negligible metabolism in human liver S9 fraction and a limited inhibition of CYP activities in yeast microsomes or S9 fractions. On the contrary, a substantial uptake by OATPs in HEK 293 cells, a strong inhibition of OATP activities in the cells, and an inhibition of P-gp and BCRP activities in reversed membrane vesicles were observed for ATSP-7041. A recent report describes that ALRN-6924, an ATSP-7041 analog, inhibited OATP activities in vivo; therefore, we focused on the interaction between ATSP-7041 and OATP1B1 to demonstrate that ATSP-7041, as a higher molecular weight stapled peptide, is a substrate and strong inhibitor of OATP1B1 activity. Our findings demonstrated the possibility of transporter-mediated DDI potential by high molecular weight stapled peptides and the necessity of their evaluation for drug development.
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Affiliation(s)
- Rika Ishikawa
- Division of Medical Safety Science, National Institute of Health Sciences, Kawasaki 210-9501, Japan
| | - Kosuke Saito
- Division of Medical Safety Science, National Institute of Health Sciences, Kawasaki 210-9501, Japan
| | - Takashi Misawa
- Division of Organic Chemistry, National Institute of Health Sciences, Kawasaki 210-9501, Japan
| | - Yosuke Demizu
- Division of Organic Chemistry, National Institute of Health Sciences, Kawasaki 210-9501, Japan
| | - Yoshiro Saito
- Division of Medical Safety Science, National Institute of Health Sciences, Kawasaki 210-9501, Japan
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4
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Liu F, van Heel AJ, Chen J, Kuipers OP. Functional production of clostridial circularin A in Lactococcus lactis NZ9000 and mutational analysis of its aromatic and cationic residues. Front Microbiol 2022; 13:1026290. [PMID: 36504829 PMCID: PMC9726714 DOI: 10.3389/fmicb.2022.1026290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 11/07/2022] [Indexed: 11/24/2022] Open
Abstract
Circular bacteriocins, also known as bacterial head-to-tail cyclized peptides, are a subgroup of ribosomally synthesized and post-translationally modified peptides (RiPPs). Compared with their conventional linear counterparts, circular bacteriocins are highly stable over a broad temperature and pH range, and circularization decreases proteolytic degradation by exopeptidases. These features render them great potential as scaffold candidates to withstand strident conditions in food- and pharmaceutical applications. However, the biosynthesis and bioactivity of circular bacteriocins still remain largely unknown. To investigate and gain more insights into the biosynthesis of circular bacteriocins and to achieve efficient production and characterization of bacteriocin variants, we developed an efficient cloning and heterologous expression system for clostridial circularin A and successfully produced this circular peptide in Lactococcus lactis NZ9000. We report three system formats with single plasmid or plasmid combinations to achieve successful cloning and functional production of circularin A in L. lactis. These systematic varieties enabled us to choose the appropriate method to efficiently obtain various constructs with desired properties. With the established heterologous systems in L. lactis, we performed several mutagenesis studies in the precursor peptide to study its structure/function relationships. The overlay activity assay revealed that these mutant variants had variable effects on different indicator strains: lysine substitution for certain glutamine residue(s) greatly decreased its bioactivity against Clostridium perfringens and L. lactis NZ9000, and alanine replacement for the cationic residues significantly reduced the activity against Lactobacillus sake ATCC 15521, whereas alanine substitution for the aromatic residues decreased its bioactivity against all three testing strains dramatically. Moreover, the conditions for bacteriocin production were optimized. Results show that supplementing the minimal medium with extra glucose (or sucrose) and immediate nisin-induction improved the peptide yield significantly. Briefly, we developed an excellent system for the production of circularin A and a wide range of variant peptides in a convenient host, as well as a method for fast detection of peptide production and activity. This system facilitated our mutagenesis studies which provided valuable insights into the effects of mutating specific residues on its biosynthesis and bioactivity, and will eventually enable more complex research into the biosynthesis of circularin A.
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Park SC, Son H, Kim YM, Lee JK, Park S, Lim HS, Lee JR, Jang MK. Design of Antimicrobial Peptides with Cell-Selective Activity and Membrane-Acting Mechanism against Drug-Resistant Bacteria. Antibiotics (Basel) 2022; 11:1619. [PMID: 36421263 PMCID: PMC9686514 DOI: 10.3390/antibiotics11111619] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 11/08/2022] [Accepted: 11/11/2022] [Indexed: 09/13/2023] Open
Abstract
Antimicrobial peptides (AMPs) can combat drug-resistant bacteria with their unique membrane-disruptive mechanisms. This study aimed to investigate the antibacterial effects of several membrane-acting peptides with amphipathic structures and positional alterations of two tryptophan residues. The synthetic peptides exhibited potent antibacterial activities in a length-dependent manner against various pathogenic drug-resistant and susceptible bacteria. In particular, the location of tryptophan near the N-terminus of AMPs simultaneously increases their antibacterial activity and toxicity. Furthermore, the growth inhibition mechanisms of these newly designed peptides involve cell penetration and destabilization of the cell membrane. These findings provide new insights into the design of peptides as antimicrobial agents and suggest that these peptides can be used as substitutes for conventional antibiotics.
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Affiliation(s)
- Seong-Cheol Park
- Department of Chemical Engineering, Sunchon National University, Suncheon 57922, Republic of Korea
| | - Hyosuk Son
- Department of Chemical Engineering, Sunchon National University, Suncheon 57922, Republic of Korea
- Department of Exhibition and Education, National Marine Biodiversity Institute of Korea, Seocheon 33662, Republic of Korea
| | - Young-Min Kim
- Department of Chemical Engineering, Sunchon National University, Suncheon 57922, Republic of Korea
| | - Jong-Kook Lee
- Department of Chemical Engineering, Sunchon National University, Suncheon 57922, Republic of Korea
| | - Soyoung Park
- Department of Chemical Engineering, Sunchon National University, Suncheon 57922, Republic of Korea
| | - Hye Song Lim
- LMO Team, National Institute of Ecology (NIE), Seocheon 33657, Republic of Korea
| | - Jung Ro Lee
- LMO Team, National Institute of Ecology (NIE), Seocheon 33657, Republic of Korea
| | - Mi-Kyeong Jang
- Department of Chemical Engineering, Sunchon National University, Suncheon 57922, Republic of Korea
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6
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Korn P, Schwieger C, Gruhle K, Garamus VM, Meister A, Ihling C, Drescher S. Azide- and diazirine-modified membrane lipids: Physicochemistry and applicability to study peptide/lipid interactions via cross-linking/mass spectrometry. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:184004. [PMID: 35841926 DOI: 10.1016/j.bbamem.2022.184004] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 07/06/2022] [Accepted: 07/07/2022] [Indexed: 06/15/2023]
Abstract
Although the incorporation of photo-activatable lipids into membranes potentially opens new avenues for studying interactions with peptides and proteins, the question of whether azide- or diazirine-modified lipids are suitable for such studies remains controversial. We have recently shown that diazirine-modified lipids can indeed form cross-links to membrane peptides after UV activation and that these cross-links can be precisely determined in their position by mass spectrometry (MS). However, we also observed an unexpected backfolding of the lipid's diazirine-containing stearoyl chain to the membrane interface challenging the potential application of this modified lipid for future cross-linking (XL)-MS studies of protein/lipid interactions. In this work, we compared an azide- (AzidoPC) and a diazirine-modified (DiazPC) membrane lipid regarding their self-assembly properties, their mixing behavior with saturated bilayer-forming phospholipids, and their reactivity upon UV activation using differential scanning calorimetry (DSC), dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and MS. Mixtures of both modified lipids with DMPC were further used for photo-chemically induced XL experiments with a transmembrane model peptide (KLAW23) to elucidate similarities and differences between the azide and the diazirine moiety. We showed that both photo-reactive lipids can be used to study lipid/peptide and lipid/protein interactions. The AzidoPC proved easier to handle, whereas the DiazPC had fewer degradation products and a higher cross-linking yield. However, the problem of backfolding occurs in both lipids; thus, it seems to be a general phenomenon.
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Affiliation(s)
- Patricia Korn
- Institute of Pharmacy-Pharmaceutical Chemistry and Bioanalytics, Charles Tanford Protein Center, Martin Luther University (MLU) Halle-Wittenberg, Kurt-Mothes-Str. 3a, 06120 Halle (Saale), Germany
| | - Christian Schwieger
- Institute of Chemistry, MLU Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle (Saale), Germany
| | - Kai Gruhle
- Institute of Pharmacy-Pharmaceutical Chemistry and Bioanalytics, Charles Tanford Protein Center, Martin Luther University (MLU) Halle-Wittenberg, Kurt-Mothes-Str. 3a, 06120 Halle (Saale), Germany; Institute of Pharmacy-Biophysical Pharmacy, MLU Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle (Saale), Germany
| | - Vasil M Garamus
- Helmholtz-Zentrum Hereon, Max-Planck-Str. 1, 21502 Geesthacht, Germany
| | - Annette Meister
- Interdisciplinary Research Center HALOmem, MLU Halle-Wittenberg, Charles Tanford Protein Center, Kurt-Mothes-Str. 3a, 06120 Halle (Saale), Germany; Institute of Biochemistry and Biotechnology-Physical Biotechnology, Charles Tanford Protein Center, MLU Halle-Wittenberg, Kurt-Mothes-Str. 3a, 06120 Halle (Saale), Germany
| | - Christian Ihling
- Institute of Pharmacy-Pharmaceutical Chemistry and Bioanalytics, Charles Tanford Protein Center, Martin Luther University (MLU) Halle-Wittenberg, Kurt-Mothes-Str. 3a, 06120 Halle (Saale), Germany; Center for Structural Mass Spectrometry, Kurt-Mothes-Str. 3, 06120 Halle (Saale), Germany
| | - Simon Drescher
- Institute of Pharmacy-Biophysical Pharmacy, MLU Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle (Saale), Germany; Phospholipid Research Center, Im Neuenheimer Feld 515, 69120 Heidelberg, Germany.
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7
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Mitchell W, Tamucci JD, Ng EL, Liu S, Birk AV, Szeto HH, May ER, Alexandrescu AT, Alder NN. Structure-activity relationships of mitochondria-targeted tetrapeptide pharmacological compounds. eLife 2022; 11:75531. [PMID: 35913044 PMCID: PMC9342957 DOI: 10.7554/elife.75531] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 07/03/2022] [Indexed: 11/13/2022] Open
Abstract
Mitochondria play a central role in metabolic homeostasis, and dysfunction of this organelle underpins the etiology of many heritable and aging-related diseases. Tetrapeptides with alternating cationic and aromatic residues such as SS-31 (elamipretide) show promise as therapeutic compounds for mitochondrial disorders. In this study, we conducted a quantitative structure-activity analysis of three alternative tetrapeptide analogs, benchmarked against SS-31, that differ with respect to aromatic side chain composition and sequence register. We present the first structural models for this class of compounds, obtained with Nuclear Magnetic Resonance (NMR) and molecular dynamics approaches, showing that all analogs except for SS-31 form compact reverse turn conformations in the membrane-bound state. All peptide analogs bound cardiolipin-containing membranes, yet they had significant differences in equilibrium binding behavior and membrane interactions. Notably, analogs had markedly different effects on membrane surface charge, supporting a mechanism in which modulation of membrane electrostatics is a key feature of their mechanism of action. The peptides had no strict requirement for side chain composition or sequence register to permeate cells and target mitochondria in mammalian cell culture assays. All four peptides were pharmacologically active in serum withdrawal cell stress models yet showed significant differences in their abilities to restore mitochondrial membrane potential, preserve ATP content, and promote cell survival. Within our peptide set, the analog containing tryptophan side chains, SPN10, had the strongest impact on most membrane properties and showed greatest efficacy in cell culture studies. Taken together, these results show that side chain composition and register influence the activity of these mitochondria-targeted peptides, helping provide a framework for the rational design of next-generation therapeutics with enhanced potency.
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Affiliation(s)
- Wayne Mitchell
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, United States
| | - Jeffrey D Tamucci
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, United States
| | - Emery L Ng
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, United States
| | - Shaoyi Liu
- Social Profit Network, Menlo Park, CA, United States
| | - Alexander V Birk
- Department of Biology, York College of CUNY, New York, NY, United States
| | - Hazel H Szeto
- Social Profit Network, Menlo Park, CA, United States
| | - Eric R May
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, United States
| | - Andrei T Alexandrescu
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, United States
| | - Nathan N Alder
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, United States
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8
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Nakao H, Nakano M. Flip-Flop Promotion Mechanisms by Model Transmembrane Peptides. Chem Pharm Bull (Tokyo) 2022; 70:519-523. [DOI: 10.1248/cpb.c22-00133] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Hiroyuki Nakao
- Department of Biointerface Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama
| | - Minoru Nakano
- Department of Biointerface Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama
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9
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Berger TM, Michaelis C, Probst I, Sagmeister T, Petrowitsch L, Puchner S, Pavkov-Keller T, Gesslbauer B, Grohmann E, Keller W. Small Things Matter: The 11.6-kDa TraB Protein is Crucial for Antibiotic Resistance Transfer Among Enterococci. Front Mol Biosci 2022; 9:867136. [PMID: 35547396 PMCID: PMC9083827 DOI: 10.3389/fmolb.2022.867136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 03/14/2022] [Indexed: 11/18/2022] Open
Abstract
Conjugative transfer is the most important means for spreading antibiotic resistance genes. It is used by Gram-positive and Gram-negative bacteria, and archaea as well. Conjugative transfer is mediated by molecular membrane-spanning nanomachines, so called Type 4 Secretion Systems (T4SS). The T4SS of the broad-host-range inc18-plasmid pIP501 is organized in a single operon encoding 15 putative transfer proteins. pIP501 was originally isolated from a clinical Streptococcus agalactiae strain but is mainly found in Enterococci. In this study, we demonstrate that the small transmembrane protein TraB is essential for pIP501 transfer. Complementation of a markerless pIP501∆traB knockout by traB lacking its secretion signal sequence did not fully restore conjugative transfer. Pull-downs with Strep-tagged TraB demonstrated interactions of TraB with the putative mating pair formation proteins, TraF, TraH, TraK, TraM, and with the lytic transglycosylase TraG. As TraB is the only putative mating pair formation complex protein containing a secretion signal sequence, we speculate on its role as T4SS recruitment factor. Moreover, structural features of TraB and TraB orthologs are presented, making an essential role of TraB-like proteins in antibiotic resistance transfer among Firmicutes likely.
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Affiliation(s)
- Tamara M.I. Berger
- Institute of Molecular Biosciences, Department of Structural Biology, University of Graz, Graz, Austria
| | - Claudia Michaelis
- Faculty of Life Sciences and Technology, Department of Microbiology, Berliner Hochschule für Technik, Berlin, Germany
| | - Ines Probst
- Division of Infectious Diseases, University Medical Center Freiburg, Freiburg, Germany
| | - Theo Sagmeister
- Institute of Molecular Biosciences, Department of Structural Biology, University of Graz, Graz, Austria
| | - Lukas Petrowitsch
- Institute of Molecular Biosciences, Department of Structural Biology, University of Graz, Graz, Austria
| | - Sandra Puchner
- Faculty of Life Sciences and Technology, Department of Microbiology, Berliner Hochschule für Technik, Berlin, Germany
| | - Tea Pavkov-Keller
- Institute of Molecular Biosciences, Department of Structural Biology, University of Graz, Graz, Austria
- Field of Excellence BioHealth, University of Graz, Graz, Austria
- BioTechMed-Graz, Graz, Austria
| | - Bernd Gesslbauer
- Institute of Pharmaceutical Sciences, Division of Pharmaceutical Chemistry, University of Graz, Graz, Austria
| | - Elisabeth Grohmann
- Faculty of Life Sciences and Technology, Department of Microbiology, Berliner Hochschule für Technik, Berlin, Germany
| | - Walter Keller
- Institute of Molecular Biosciences, Department of Structural Biology, University of Graz, Graz, Austria
- Field of Excellence BioHealth, University of Graz, Graz, Austria
- BioTechMed-Graz, Graz, Austria
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10
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Bhat RAH, Khangembam VC, Thakuria D, Pant V, Tandel RS, Tripathi G, Sarma D. Antimicrobial Activity of an Artificially Designed Peptide Against Fish Pathogens. Microbiol Res 2022; 260:127039. [DOI: 10.1016/j.micres.2022.127039] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 04/02/2022] [Accepted: 04/08/2022] [Indexed: 12/28/2022]
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11
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The Electrostatic Basis of Diacylglycerol Pyrophosphate—Protein Interaction. Cells 2022; 11:cells11020290. [PMID: 35053406 PMCID: PMC8774204 DOI: 10.3390/cells11020290] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 01/04/2022] [Accepted: 01/07/2022] [Indexed: 01/08/2023] Open
Abstract
Diacylglycerol pyrophosphate (DGPP) is an anionic phospholipid formed in plants, yeast, and parasites under multiple stress stimuli. It is synthesized by the phosphorylation action of phosphatidic acid (PA) kinase on phosphatidic acid, a signaling lipid with multifunctional properties. PA functions in the membrane through the interaction of its negatively charged phosphomonoester headgroup with positively charged proteins and ions. DGPP, like PA, can interact electrostatically via the electrostatic-hydrogen bond switch mechanism but differs from PA in its overall charge and shape. The formation of DGPP from PA alters the physicochemical properties as well as the structural dynamics of the membrane. This potentially impacts the molecular and ionic binding of cationic proteins and ions with the DGPP enriched membrane. However, the results of these important interactions in the stress response and in DGPP’s overall intracellular function is unknown. Here, using 31P MAS NMR, we analyze the effect of the interaction of low DGPP concentrations in model membranes with the peptides KALP23 and WALP23, which are flanked by positively charged Lysine and neutral Tryptophan residues, respectively. Our results show a significant effect of KALP23 on the charge of DGPP as compared to WALP23. There was, however, no significant effect on the charge of the phosphomonoester of DGPP due to the interaction with positively charged lipids, dioleoyl trimethylammonium propane (DOTAP) and dioleoyl ethyl-phosphatidylcholine (EtPC). Divalent calcium and magnesium cations induce deprotonation of the DGPP headgroup but showed no noticeable differences on DGPP’s charge. Our results lead to a novel model for DGPP—protein interaction.
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12
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Bis(Tryptophan) Amphiphiles Form Ion Conducting Pores and Enhance Antimicrobial Activity against Resistant Bacteria. Antibiotics (Basel) 2021; 10:antibiotics10111391. [PMID: 34827329 PMCID: PMC8614774 DOI: 10.3390/antibiotics10111391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 11/05/2021] [Accepted: 11/08/2021] [Indexed: 11/17/2022] Open
Abstract
The compounds referred to as bis(tryptophan)s (BTs) have shown activity as antimicrobials. The hypothesis that the activity of these novel amphiphiles results from insertion in bilayer membranes and transport of cations is supported by planar bilayer voltage-clamp studies reported herein. In addition, fluorescence studies of propidium iodide penetration of vital bacteria confirmed enhanced permeability. It was also found that BTs having either meta-phenylene or n-dodecylene linkers function as effective adjuvants to enhance the properties of FDA-approved antimicrobials against organisms such as S. aureus. In one example, a BT-mediated synergistic effect enhanced the potency of norfloxacin against S. aureus by 128-fold. In order to determine if related compounds in which tryptophan was replaced by other common amino acids (H2N-Aaa-linker-Aaa-NH2) we active, a family of analogs have been prepared, characterized, and tested as controls for both antimicrobial activity and as adjuvants for other antimicrobials against both Gram-negative and Gram-positive bacteria. The most active of the compounds surveyed remain the bis(tryptophan) derivatives.
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13
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Dorner J, Korn P, Gruhle K, Ramsbeck D, Garamus VM, Lilie H, Meister A, Schwieger C, Ihling C, Sinz A, Drescher S. A Diazirine-Modified Membrane Lipid to Study Peptide/Lipid Interactions - Chances and Challenges. Chemistry 2021; 27:14586-14593. [PMID: 34406694 PMCID: PMC8597076 DOI: 10.1002/chem.202102048] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Indexed: 01/19/2023]
Abstract
Although incorporation of photo‐activatable lipids into membranes potentially opens up novel avenues for investigating interactions with proteins, the question of whether diazirine‐modified lipids are suitable for such studies, remains under debate. Focusing on the potential for studying lipid/peptide interactions by cross‐linking mass spectrometry (XL‐MS), we developed a diazirine‐modified lipid (DiazPC), and examined its behaviour in membranes incorporating the model α‐helical peptide LAVA20. We observed an unexpected backfolding of the diazirine‐containing stearoyl chain of the lipid. This surprising behaviour challenges the potential application of DiazPC for future XL‐MS studies of peptide and protein/lipid interactions. The observations made for DiazPC most likely represent a general phenomenon for any type of membrane lipids with a polar moiety incorporated into the alkyl chain. Our finding is therefore of importance for future protein/lipid interaction studies relying on modified lipid probes.
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Affiliation(s)
- Julia Dorner
- Institute of Pharmacy-Pharmaceutical Chemistry and Bioanalytics, Martin Luther University (MLU) Halle-Wittenberg, Kurt-Mothes-Str. 3, 06120, Halle (Saale), Germany
| | - Patricia Korn
- Institute of Pharmacy-Pharmaceutical Chemistry and Bioanalytics, Martin Luther University (MLU) Halle-Wittenberg, Kurt-Mothes-Str. 3, 06120, Halle (Saale), Germany
| | - Kai Gruhle
- Institute of Pharmacy-Pharmaceutical Chemistry and Bioanalytics, Martin Luther University (MLU) Halle-Wittenberg, Kurt-Mothes-Str. 3, 06120, Halle (Saale), Germany.,Institute of Pharmacy-Biophysical Pharmacy, MLU Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120, Halle (Saale), Germany
| | - Daniel Ramsbeck
- Fraunhofer Institute for Cell Therapy and Immunology IZI, Weinbergweg 22, 06120, Halle (Saale), Germany.,Institute of Pharmacy, University Leipzig, Brüderstr. 34, 04103, Leipzig, Germany
| | - Vasil M Garamus
- Helmholtz-Zentrum Hereon, Max-Planck-Str. 1, 21502, Geesthacht, Germany
| | - Hauke Lilie
- Institute for Biochemistry and Biotechnology-Technical Biochemistry, MLU Halle-Wittenberg, Kurt-Mothes-Str. 3, 06120, Halle (Saale), Germany
| | - Annette Meister
- Institute of Biochemistry and Biotechnology-Physical Biotechnology Charles Tanford Protein Center, MLU Halle-Wittenberg, Kurt-Mothes-Str. 3a, 06120, Halle (Saale), Germany.,Interdisciplinary Research Center HALOmem, MLU Halle-Wittenberg Charles Tanford Protein Center, Kurt-Mothes-Str. 3a, 06120, Halle (Saale), Germany
| | - Christian Schwieger
- Interdisciplinary Research Center HALOmem, MLU Halle-Wittenberg Charles Tanford Protein Center, Kurt-Mothes-Str. 3a, 06120, Halle (Saale), Germany
| | - Christian Ihling
- Institute of Pharmacy-Pharmaceutical Chemistry and Bioanalytics, Martin Luther University (MLU) Halle-Wittenberg, Kurt-Mothes-Str. 3, 06120, Halle (Saale), Germany.,Center for Structural Mass Spectrometry, Kurt-Mothes-Str. 3, 06120, Halle (Saale), Germany
| | - Andrea Sinz
- Institute of Pharmacy-Pharmaceutical Chemistry and Bioanalytics, Martin Luther University (MLU) Halle-Wittenberg, Kurt-Mothes-Str. 3, 06120, Halle (Saale), Germany.,Center for Structural Mass Spectrometry, Kurt-Mothes-Str. 3, 06120, Halle (Saale), Germany
| | - Simon Drescher
- Institute of Pharmacy-Biophysical Pharmacy, MLU Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120, Halle (Saale), Germany.,Phospholipid Research Center, Im Neuenheimer Feld 515, 69120, Heidelberg, Germany
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14
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Tryptophan, an Amino-Acid Endowed with Unique Properties and Its Many Roles in Membrane Proteins. CRYSTALS 2021. [DOI: 10.3390/cryst11091032] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Tryptophan is an aromatic amino acid with unique physico-chemical properties. It is often encountered in membrane proteins, especially at the level of the water/bilayer interface. It plays a role in membrane protein stabilization, anchoring and orientation in lipid bilayers. It has a hydrophobic character but can also engage in many types of interactions, such as π–cation or hydrogen bonds. In this review, we give an overview of the role of tryptophan in membrane proteins and a more detailed description of the underlying noncovalent interactions it can engage in with membrane partners.
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15
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Mahajan M, Bharambe N, Shang Y, Lu B, Mandal A, Madan Mohan P, Wang R, Boatz JC, Manuel Martinez Galvez J, Shnyrova AV, Qi X, Buck M, van der Wel PCA, Ramachandran R. NMR identification of a conserved Drp1 cardiolipin-binding motif essential for stress-induced mitochondrial fission. Proc Natl Acad Sci U S A 2021; 118:e2023079118. [PMID: 34261790 PMCID: PMC8307854 DOI: 10.1073/pnas.2023079118] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Mitochondria form tubular networks that undergo coordinated cycles of fission and fusion. Emerging evidence suggests that a direct yet unresolved interaction of the mechanoenzymatic GTPase dynamin-related protein 1 (Drp1) with mitochondrial outer membrane-localized cardiolipin (CL), externalized under stress conditions including mitophagy, catalyzes essential mitochondrial hyperfragmentation. Here, using a comprehensive set of structural, biophysical, and cell biological tools, we have uncovered a CL-binding motif (CBM) conserved between the Drp1 variable domain (VD) and the unrelated ADP/ATP carrier (AAC/ANT) that intercalates into the membrane core to effect specific CL interactions. CBM mutations that weaken VD-CL interactions manifestly impair Drp1-dependent fission under stress conditions and induce "donut" mitochondria formation. Importantly, VD membrane insertion and GTP-dependent conformational rearrangements mediate only transient CL nonbilayer topological forays and high local membrane constriction, indicating that Drp1-CL interactions alone are insufficient for fission. Our studies establish the structural and mechanistic bases of Drp1-CL interactions in stress-induced mitochondrial fission.
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Affiliation(s)
- Mukesh Mahajan
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44106
| | - Nikhil Bharambe
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44106
| | - Yutong Shang
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44106
| | - Bin Lu
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44106
| | - Abhishek Mandal
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Pooja Madan Mohan
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44106
| | - Rihua Wang
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44106
| | - Jennifer C Boatz
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
| | - Juan Manuel Martinez Galvez
- Instituto Biofisika and Department of Biochemistry and Molecular Biology, University of the Basque Country, 48940 Leioa, Spain
| | - Anna V Shnyrova
- Instituto Biofisika and Department of Biochemistry and Molecular Biology, University of the Basque Country, 48940 Leioa, Spain
| | - Xin Qi
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44106
- Center for Mitochondrial Diseases, Case Western Reserve University School of Medicine, Cleveland, OH 44106
| | - Matthias Buck
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44106
- Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, Cleveland, OH 44106
| | - Patrick C A van der Wel
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261
- Zernike Institute for Advanced Materials, University of Groningen, 9700 AB Groningen, The Netherlands
| | - Rajesh Ramachandran
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44106;
- Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, Cleveland, OH 44106
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16
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Palacios-Ortega J, García-Linares S, Rivera-de-Torre E, Heras-Márquez D, Gavilanes JG, Slotte JP, Martínez-Del-Pozo Á. Structural foundations of sticholysin functionality. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2021; 1869:140696. [PMID: 34246789 DOI: 10.1016/j.bbapap.2021.140696] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 07/05/2021] [Accepted: 07/06/2021] [Indexed: 01/22/2023]
Abstract
Actinoporins constitute a family of α pore-forming toxins produced by sea anemones. The soluble fold of these proteins consists of a β-sandwich flanked by two α-helices. Actinoporins exert their activity by specifically recognizing sphingomyelin at their target membranes. Once there, they penetrate the membrane with their N-terminal α-helices, a process that leads to the formation of cation-selective pores. These pores kill the target cells by provoking an osmotic shock on them. In this review, we examine the role and relevance of the structural features of actinoporins, down to the residue level. We look at the specific amino acids that play significant roles in the function of actinoporins and their fold. Particular emphasis is given to those residues that display a high degree of conservation across the actinoporin sequences known to date. In light of the latest findings in the field, the membrane requirements for pore formation, the effect of lipid composition, and the process of pore formation are also discussed.
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Affiliation(s)
- Juan Palacios-Ortega
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense, Madrid, Spain; Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland.
| | - Sara García-Linares
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense, Madrid, Spain
| | - Esperanza Rivera-de-Torre
- Department of Biochemistry and Biotechnology, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Diego Heras-Márquez
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense, Madrid, Spain
| | - José G Gavilanes
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense, Madrid, Spain
| | - J Peter Slotte
- Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
| | - Álvaro Martínez-Del-Pozo
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense, Madrid, Spain
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17
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Naßwetter LC, Fischer M, Scheidt HA, Heerklotz H. Membrane-water partitioning - Tackling the challenges of poorly soluble drugs using chaotropic co-solvents. Biophys Chem 2021; 277:106654. [PMID: 34265547 DOI: 10.1016/j.bpc.2021.106654] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 06/22/2021] [Accepted: 06/24/2021] [Indexed: 12/01/2022]
Abstract
Many newly developed drugs suffer from poor water solubility and low bioavailability and hence, need special formulation vehicles like vesicular or micellar drug delivery systems. The knowledge of their membrane-water partition coefficient K becomes critical as is governs drug loading and release from the vehicle, as well as absorption into the body. The dilemma is that measuring K is particularly challenging for these very compounds. Here we establish a strategy to resolve this problem. We added DMSO to shift K and solubility into a convenient range and extrapolated these results back to zero-DMSO. Isothermal titration calorimetry revealed that logK of the kinase inhibitor Lapatinib decreased proportionally to DMSO content (2.5 - 20v%) with a slope of -1/20v% (m value = 28 kJ/mol). This implies a K of 84 mM-1 in DMSO-free buffer. This strategy should be transferable to other poorly soluble drugs and further detection methods.
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Affiliation(s)
- Leonie C Naßwetter
- Institute of Pharmaceutical Sciences, Albert-Ludwigs-Universität, Hermann-Herder-Straße 9, 79104 Freiburg, Germany.
| | - Markus Fischer
- Institute for Medical Physics and Biophysics, Leipzig University, Härtelstr. 16-18, 04107 Leipzig, Germany.
| | - Holger A Scheidt
- Institute for Medical Physics and Biophysics, Leipzig University, Härtelstr. 16-18, 04107 Leipzig, Germany.
| | - Heiko Heerklotz
- Institute of Pharmaceutical Sciences, Albert-Ludwigs-Universität, Hermann-Herder-Straße 9, 79104 Freiburg, Germany; Signalling Research Centres BIOSS and CIBSS, Albert-Ludwigs-Universität, Schänzlestraße 18, 79104 Freiburg; Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College St, Toronto ON, M5S 3M2, Canada.
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18
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Kloos M, Sharma A, Enderlein J, Diederichsen U. Transmembrane β-peptide helices as molecular rulers at the membrane surface. J Pept Sci 2021; 27:e3355. [PMID: 34077994 DOI: 10.1002/psc.3355] [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: 04/07/2021] [Revised: 05/17/2021] [Accepted: 05/17/2021] [Indexed: 11/08/2022]
Abstract
β-Peptides are known to form 14-helices with high conformational rigidity, helical persistence length, and well-defined spacing and orientation regularity of amino acid side chains. Therefore, β-peptides are well suited to serve as backbone structures for molecular rulers. On the one hand, they can be functionalized in a site-specific manner with molecular probes or fluorophores, and on the other hand, the β-peptide helices can be recognized and anchored in a biological environment of interest. In this study, the β-peptide helices were anchored in lipid bilayer membranes, and the helices were elongated in the outer membrane environment. The distances of the covalently bound probes to the membrane surface were determined using graphene-induced energy transfer (GIET) spectroscopy, a method based on the distance-dependent quenching of a fluorescent molecule by a nearby single graphene sheet. As a proof of principle, the predicted distances were determined for two fluorophores bound to the membrane-anchored β-peptide molecular ruler.
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Affiliation(s)
- Martin Kloos
- Institut für Organische und Biomolekulare Chemie, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Akshita Sharma
- III. Physikalisches Institut-Biophysik, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Jörg Enderlein
- III. Physikalisches Institut-Biophysik, Georg-August-Universität Göttingen, Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), Georg-August-Universität Göttingen, Göttingen, Germany
| | - Ulf Diederichsen
- Institut für Organische und Biomolekulare Chemie, Georg-August-Universität Göttingen, Göttingen, Germany
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19
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Tracz M, Górniak I, Szczepaniak A, Białek W. E3 Ubiquitin Ligase SPL2 Is a Lanthanide-Binding Protein. Int J Mol Sci 2021; 22:5712. [PMID: 34071935 PMCID: PMC8198723 DOI: 10.3390/ijms22115712] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 05/14/2021] [Accepted: 05/17/2021] [Indexed: 01/17/2023] Open
Abstract
The SPL2 protein is an E3 ubiquitin ligase of unknown function. It is one of only three types of E3 ligases found in the outer membrane of plant chloroplasts. In this study, we show that the cytosolic fragment of SPL2 binds lanthanide ions, as evidenced by fluorescence measurements and circular dichroism spectroscopy. We also report that SPL2 undergoes conformational changes upon binding of both Ca2+ and La3+, as evidenced by its partial unfolding. However, these structural rearrangements do not interfere with SPL2 enzymatic activity, as the protein retains its ability to auto-ubiquitinate in vitro. The possible applications of lanthanide-based probes to identify protein interactions in vivo are also discussed. Taken together, the results of this study reveal that the SPL2 protein contains a lanthanide-binding site, showing for the first time that at least some E3 ubiquitin ligases are also capable of binding lanthanide ions.
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Affiliation(s)
- Michał Tracz
- Department of Biophysics, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland; (M.T.); (I.G.); (A.S.)
| | - Ireneusz Górniak
- Department of Biophysics, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland; (M.T.); (I.G.); (A.S.)
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Andrzej Szczepaniak
- Department of Biophysics, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland; (M.T.); (I.G.); (A.S.)
| | - Wojciech Białek
- Department of Biophysics, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland; (M.T.); (I.G.); (A.S.)
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20
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Bhanot S, Hemminger G, Martin CL, Aller SG, Forrest JN. A nonolfactory shark adenosine receptor activates CFTR with unique pharmacology and structural features. Am J Physiol Cell Physiol 2021; 320:C892-C901. [PMID: 33689481 DOI: 10.1152/ajpcell.00481.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Adenosine receptors (ADORs) are G protein-coupled purinoceptors that have several functions including regulation of chloride secretion via cystic fibrosis transmembrane conductance regulator (CFTR) in human airway and kidney. We cloned an ADOR from Squalus acanthias (shark) that likely regulates CFTR in the rectal gland. Phylogenic and expression analyses indicate that elasmobranch ADORs are nonolfactory and appear to represent extant predecessors of mammalian ADORs. We therefore designate the shark ADOR as the A0 receptor. We coexpressed A0 with CFTR in Xenopus laevis oocytes and characterized the coupling of A0 to the chloride channel. Two-electrode voltage clamping was performed, and current-voltage (I-V) responses were recorded to monitor CFTR status. Only in A0- and CFTR-coinjected oocytes did adenosine analogs produce a significant concentration-dependent activation of CFTR consistent with its electrophysiological signature. A pharmacological profile for A0 was obtained for ADOR agonists and antagonists that differed markedly from all mammalian ADOR subtypes [agonists: R-phenyl-isopropyl adenosine (R-PIA) > S-phenyl-isopropyl adenosine (S-PIA) > CGS21680 > N6-cyclopentyladenosine (CPA) > 2-chloroadenosine (2ClAdo) > CV1808 = N6-[2-(3,5-dimethoxyphenyl)-2-(2-methylphenyl)ethyl]adenosine (DPMA) > N-ethyl-carboxyl adenosine (NECA); and antagonists: 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) > PD115199 > 1,3-dimethyl-8-phenylxanthine (8PT) > CGS15943]. Structures of human ADORs permitted a high-confidence homology model of the shark A0 core that revealed unique structural features of ancestral receptors. We conclude that 1) A0 is a novel and unique adenosine receptor ancestor by functional and structural criteria; 2) A0 likely activates CFTR in vivo, and this receptor activates CFTR in oocytes, indicating an evolutionary coupling between ADORs and chloride secretion; and 3) A0 appears to be a nonolfactory evolutionary ancestor of all four mammalian ADOR subtypes.
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Affiliation(s)
- Sumeet Bhanot
- Renal Section, Department of Medicine, Yale University School of Medicine, New Haven, Connecticut.,The Mount Desert Island Biological Laboratory, Salisbury Cove, Maine
| | - Gabriele Hemminger
- Renal Section, Department of Medicine, Yale University School of Medicine, New Haven, Connecticut.,The Mount Desert Island Biological Laboratory, Salisbury Cove, Maine
| | - Cole L Martin
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Stephen G Aller
- Renal Section, Department of Medicine, Yale University School of Medicine, New Haven, Connecticut.,The Mount Desert Island Biological Laboratory, Salisbury Cove, Maine.,Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, Alabama
| | - John N Forrest
- Renal Section, Department of Medicine, Yale University School of Medicine, New Haven, Connecticut.,The Mount Desert Island Biological Laboratory, Salisbury Cove, Maine
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21
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Tkach I, Diederichsen U, Bennati M. Studies of transmembrane peptides by pulse dipolar spectroscopy with semi-rigid TOPP spin labels. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2021; 50:143-157. [PMID: 33640998 PMCID: PMC8071797 DOI: 10.1007/s00249-021-01508-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 01/25/2021] [Accepted: 01/29/2021] [Indexed: 12/01/2022]
Abstract
Electron paramagnetic resonance (EPR)-based pulsed dipolar spectroscopy measures the dipolar interaction between paramagnetic centers that are separated by distances in the range of about 1.5-10 nm. Its application to transmembrane (TM) peptides in combination with modern spin labelling techniques provides a valuable tool to study peptide-to-lipid interactions at a molecular level, which permits access to key parameters characterizing the structural adaptation of model peptides incorporated in natural membranes. In this mini-review, we summarize our approach for distance and orientation measurements in lipid environment using novel semi-rigid TOPP [4-(3,3,5,5-tetramethyl-2,6-dioxo-4-oxylpiperazin-1-yl)-L-phenylglycine] labels specifically designed for incorporation in TM peptides. TOPP labels can report single peak distance distributions with sub-angstrom resolution, thus offering new capabilities for a variety of TM peptide investigations, such as monitoring of various helix conformations or measuring of tilt angles in membranes.
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Affiliation(s)
- Igor Tkach
- Max Planck Institute for Biophysical Chemistry, RG Electron-Spin Resonance Spectroscopy, 37077, Göttingen, Germany.
| | - Ulf Diederichsen
- Department of Organic and Biomolecular Chemistry, University of Göttingen, 37077, Göttingen, Germany
| | - Marina Bennati
- Max Planck Institute for Biophysical Chemistry, RG Electron-Spin Resonance Spectroscopy, 37077, Göttingen, Germany
- Department of Organic and Biomolecular Chemistry, University of Göttingen, 37077, Göttingen, Germany
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22
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Necelis MR, Santiago-Ortiz LE, Caputo GA. Investigation of the Role of Aromatic Residues in the Antimicrobial Peptide BuCATHL4B. Protein Pept Lett 2021; 28:388-402. [PMID: 32798369 PMCID: PMC8259864 DOI: 10.2174/0929866527666200813202918] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 06/29/2020] [Accepted: 07/02/2020] [Indexed: 01/04/2023]
Abstract
BACKGROUND Antimicrobial Peptides (AMPs) are an attractive alternative to traditional small molecule antibiotics as AMPs typically target the bacterial cell membrane. A Trp-rich peptide sequence derived from water buffalo (Bubalus bubalis), BuCATHL4B was previously identified as a broad-spectrum antimicrobial peptide. OBJECTIVE In this work, native Trp residues were replaced with other naturally occurring aromatic amino acids to begin to elucidate the importance of these residues on peptide activity. METHODS Minimal Inhibitory Concentration (MIC) results demonstrated activity against seven strains of bacteria. Membrane and bilayer permeabilization assays were performed to address the role of bilayer disruption in the activity of the peptides. Lipid vesicle binding and quenching experiments were also performed to gain an understanding of how the peptides interacted with lipid bilayers. RESULTS MIC results indicate the original, tryptophan-rich sequence, and the phenylalanine substituted sequences exhibit strong inhibition of bacterial growth. In permeabilization assays, peptides with phenylalanine substitutions have higher levels of membrane permeabilization than those substituted with tyrosine. In addition, one of the two-tyrosine substituted sequence, YWY, behaves most differently in the lowest antimicrobial activity, showing no permeabilization of bacterial membranes. Notably the antimicrobial activity is inherently species dependent, with varying levels of activity against different bacteria. CONCLUSION There appears to be little correlation between membrane permeabilization and activity, indicating these peptides may have additional mechanisms of action beyond membrane disruption. The results also identify two sequences, denoted FFF and YYW, which retain antibacterial activity but have markedly reduced hemolytic activity.
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Affiliation(s)
- Matthew R Necelis
- Department of Chemistry and Biochemistry, Rowan University, Glassboro, NJ, United States
| | | | - Gregory A Caputo
- Department of Chemistry and Biochemistry, Rowan University, Glassboro, NJ, United States
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23
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Harris NJ, Pellowe GA, Booth PJ. Cell-free expression tools to study co-translational folding of alpha helical membrane transporters. Sci Rep 2020; 10:9125. [PMID: 32499529 PMCID: PMC7272624 DOI: 10.1038/s41598-020-66097-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 05/15/2020] [Indexed: 11/28/2022] Open
Abstract
Most helical membrane proteins fold co-translationally during unidirectional polypeptide elongation by the ribosome. Studies thus far, however, have largely focussed on refolding full-length proteins from artificially induced denatured states that are far removed from the natural co-translational process. Cell-free translation offers opportunities to remedy this deficit in folding studies and has previously been used for membrane proteins. We exploit this cell-free approach to develop tools to probe co-translational folding. We show that two transporters from the ubiquitous Major Facilitator Superfamily can successfully insert into a synthetic bilayer without the need for translocon insertase apparatus that is essential in vivo. We also assess the cooperativity of domain insertion, by expressing the individual transporter domains cell-free. Furthermore, we manipulate the cell-free reaction to pause and re-start protein synthesis at specific points in the protein sequence. We find that full-length protein can still be made when stalling after the first N terminal helix has inserted into the bilayer. However, stalling after the first three helices have exited the ribosome cannot be successfully recovered. These three helices cannot insert stably when ribosome-bound during co-translational folding, as they require insertion of downstream helices.
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Affiliation(s)
- Nicola J Harris
- King's College London, Department of Chemistry, Britannia House, 7 Trinity Street, London, SE1 1DB, UK
| | - Grant A Pellowe
- King's College London, Department of Chemistry, Britannia House, 7 Trinity Street, London, SE1 1DB, UK
| | - Paula J Booth
- King's College London, Department of Chemistry, Britannia House, 7 Trinity Street, London, SE1 1DB, UK.
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24
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Varadarajan V, Desikan R, Ayappa KG. Assessing the extent of the structural and dynamic modulation of membrane lipids due to pore forming toxins: insights from molecular dynamics simulations. SOFT MATTER 2020; 16:4840-4857. [PMID: 32421131 DOI: 10.1039/d0sm00086h] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Infections caused by many virulent bacterial strains are triggered by the release of pore forming toxins (PFTs), which form oligomeric transmembrane pore complexes on the target plasma membrane. The spatial extent of the perturbation to the surrounding lipids during pore formation is relatively unexplored. Using all-atom molecular dynamics simulations, we investigate the changes in the structure and dynamics of lipids in a 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) lipid bilayer in the presence of contrasting PFTs. Cytolysin A (ClyA), an α toxin with its inserted wedge shaped bundle of inserted α helices, induces significant asymmetry across the membrane leaflets in comparison with α hemolysin (AHL), a β toxin. Despite the differences in hydrophobic mismatch and uniquely different topologies of the two oligomers, perturbations to lipid order as reflected in the tilt angle and order parameters and membrane thinning are short ranged, lying within ∼2.5 nm from the periphery of either pore complex, and commensurate with distances typically associated with van der Waals forces. In contrast, the spatial extent of perturbations to the lipid dynamics extends outward to at least 4 nm for both proteins, and the continuous survival probabilities reveal the presence of a tightly bound shell of lipids in this region. Displacement probability distributions show long tails and the distinctly non-Gaussian features reflect the induced dynamic heterogeneity. A detailed profiling of the protein-lipid contacts with tyrosine, tryptophan, lysine and arginine residues shows increased non-polar contacts in the cytoplasmic leaflet for both PFTs, with a higher number of atomic contacts in the case of AHL in the extracellular leaflet due to the mushroom-like topology of the pore complex. The short ranged nature of the perturbations observed in this simple one component membrane suggests inherent plasticity of membrane lipids enabling the recovery of the structure and membrane fluidity even in the presence of these large oligomeric transmembrane protein assemblies. This observation has implications in membrane repair processes such as budding or vesicle fusion events used to mitigate PFT virulence, where the underlying lipid dynamics and fluidity in the vicinity of the pore complex are expected to play an important role.
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Affiliation(s)
- Vadhana Varadarajan
- Department of Chemical Engineering, Indian Institute of Science, Bangalore-560012, India.
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25
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Syga Ł, de Vries RH, van Oosterhout H, Bartelds R, Boersma AJ, Roelfes G, Poolman B. A Trifunctional Linker for Palmitoylation and Peptide and Protein Localization in Biological Membranes. Chembiochem 2020; 21:1320-1328. [PMID: 31814256 PMCID: PMC7317724 DOI: 10.1002/cbic.201900655] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Indexed: 01/09/2023]
Abstract
Attachment of lipophilic groups is an important post-translational modification of proteins, which involves the coupling of one or more anchors such as fatty acids, isoprenoids, phospholipids, or glycosylphosphatidyl inositols. To study its impact on the membrane partitioning of hydrophobic peptides or proteins, we designed a tyrosine-based trifunctional linker. The linker allows the facile incorporation of two different functionalities at a cysteine residue in a single step. We determined the effect of the lipid modification on the membrane partitioning of the synthetic α-helical model peptide WALP with or without here and in all cases below; palmitoyl groups in giant unilamellar vesicles that contain a liquid-ordered (Lo ) and liquid-disordered (Ld ) phase. Introduction of two palmitoyl groups did not alter the localization of the membrane peptides, nor did the membrane thickness or lipid composition. In all cases, the peptide was retained in the Ld phase. These data demonstrate that the Lo domain in model membranes is highly unfavorable for a single membrane-spanning peptide.
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Affiliation(s)
- Łukasz Syga
- Department of BiochemistryGroningen Biomolecular Sciences andBiotechnology Institute and Zernike Institute for Advanced MaterialsUniversity of GroningenNijenborgh 49747 AGGroningenThe Netherlands
| | - Reinder H. de Vries
- Department of Biomolecular Chemistry and CatalysisStratingh Institute for ChemistryUniversity of GroningenNijenborgh 49747 AGGroningenThe Netherlands
| | - Hugo van Oosterhout
- Department of Biomolecular Chemistry and CatalysisStratingh Institute for ChemistryUniversity of GroningenNijenborgh 49747 AGGroningenThe Netherlands
| | - Rianne Bartelds
- Department of BiochemistryGroningen Biomolecular Sciences andBiotechnology Institute and Zernike Institute for Advanced MaterialsUniversity of GroningenNijenborgh 49747 AGGroningenThe Netherlands
| | - Arnold J. Boersma
- DWI Leibniz Institute for Interactive MaterialsForckenbeckstrasse 5052074AachenGermany
| | - Gerard Roelfes
- Department of Biomolecular Chemistry and CatalysisStratingh Institute for ChemistryUniversity of GroningenNijenborgh 49747 AGGroningenThe Netherlands
| | - Bert Poolman
- Department of BiochemistryGroningen Biomolecular Sciences andBiotechnology Institute and Zernike Institute for Advanced MaterialsUniversity of GroningenNijenborgh 49747 AGGroningenThe Netherlands
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26
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Bai J, Wang J, Ravula T, Im SC, Anantharamaiah GM, Waskell L, Ramamoorthy A. Expression, purification, and functional reconstitution of 19F-labeled cytochrome b5 in peptide nanodiscs for NMR studies. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2020; 1862:183194. [PMID: 31953231 PMCID: PMC7050362 DOI: 10.1016/j.bbamem.2020.183194] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 01/06/2020] [Accepted: 01/10/2020] [Indexed: 02/07/2023]
Abstract
Microsomal cytochrome b5 (cytb5) is a membrane-bound protein capable of donating the second electron to cytochrome P450s (cytP450s) in the cytP450s monooxygenase reactions. Recent studies have demonstrated the importance of the transmembrane domain of cytb5 in the interaction with cytP450 by stabilizing its monomeric structure. While recent NMR studies have provided high-resolution insights into the structural interactions between the soluble domains of ~16-kDa cytb5 and ~57-kDa cytP450 in a membrane environment, there is need for studies to probe the residues in the transmembrane region as well as to obtain intermolecular distance constraints to better understand the very large size cytb5-cytP450 complex structure in a near native membrane environment. In this study, we report the expression, purification, functional reconstitution of 19F-labeled full-length rabbit cytb5 in peptide based nanodiscs for structural studies using NMR spectroscopy. Size exclusion chromatography, dynamic light scattering, transmission electron microscopy, and NMR experiments show a stable reconstitution of cytb5 in 4F peptide-based lipid-nanodiscs. The reported results demonstrate the use of 19F NMR experiments to study 19F-labeled (with 5-fluorotryptophan (5FW)) cytb5 reconstituted in peptide-nanodiscs and the detection of residues from the transmembrane domain by solution 19F NMR experiments. 19F NMR results revealing the interaction of the transmembrane domain of cytb5 with the full-length rabbit cytochrome P450 2B4 (CYP2B4) are also presented. We expect the results presented in this study to be useful to devise approaches to probe the structure, dynamics and functional roles of transmembrane domains of a membrane protein, and also to measure intermolecular 19F-19F distance constraints to determine the structural interactions between the transmembrane domains.
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Affiliation(s)
- Jia Bai
- Biophysics Program, Department of Chemistry, Biomedical Engineering, Macromolecular Science and Engineering, The University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Jian Wang
- Biophysics Program, Department of Chemistry, Biomedical Engineering, Macromolecular Science and Engineering, The University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Thirupathi Ravula
- Biophysics Program, Department of Chemistry, Biomedical Engineering, Macromolecular Science and Engineering, The University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Sang-Choul Im
- Department of Internal Medicine, The University of Michigan, and VA Medical Center, Ann Arbor, MI 48105, USA
| | | | - Lucy Waskell
- Department of Anesthesiology, The University of Michigan, and VA Medical Center, Ann Arbor, MI 48105, USA
| | - Ayyalusamy Ramamoorthy
- Biophysics Program, Department of Chemistry, Biomedical Engineering, Macromolecular Science and Engineering, The University of Michigan, Ann Arbor, MI 48109-1055, USA.
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27
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Designing minimalist membrane proteins. Biochem Soc Trans 2020; 47:1233-1245. [PMID: 31671181 PMCID: PMC6824673 DOI: 10.1042/bst20190170] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 08/05/2019] [Accepted: 08/12/2019] [Indexed: 12/13/2022]
Abstract
The construction of artificial membrane proteins from first principles is of fundamental interest and holds considerable promise for new biotechnologies. This review considers the potential advantages of adopting a strictly minimalist approach to the process of membrane protein design. As well as the practical benefits of miniaturisation and simplicity for understanding sequence-structure-function relationships, minimalism should also support the abstract conceptualisation of membrane proteins as modular components for synthetic biology. These ideas are illustrated with selected examples that focus upon α-helical membrane proteins, and which demonstrate how such minimalist membrane proteins might be integrated into living biosystems.
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28
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Influence of interfacial tryptophan residues on an arginine-flanked transmembrane helix. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183134. [PMID: 31738898 DOI: 10.1016/j.bbamem.2019.183134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 10/31/2019] [Accepted: 11/01/2019] [Indexed: 10/25/2022]
Abstract
The transmembrane helices of membrane proteins often are flanked by interfacial charged or aromatic residues that potentially help to anchor the membrane-spanning protein. For isolated single-span helices, the interfacial residues may be especially important for stabilizing particular tilted transmembrane orientations. The peptide RWALP23 (acetyl-GR2ALW(LA)6LWLAR22A-amide) has been employed to investigate the interplay between interfacial arginines and tryptophans. Here we replace the tryptophans of RWALP23 with A5 and A19, to investigate arginines alone with respect to helix fraying and orientation in varying lipid bilayers. Deuterated alanines incorporated into the central sequence allow the orientation and stability of the core helix to be assessed by means of solid -state 2H NMR in bilayers of DOPC, DMPC and DLPC. The helix tilt from the bilayer normal is found to increase slightly when R2 and R22 are present, and increases still further when the tryptophans W5 and W19 are replaced by alanines. The extent of helix dynamic averaging remains low in all cases. The preferred helix azimuthal rotation is essentially constant for all of the helices in each of the lipid membranes considered here. The alanines located outside of the core region of the peptide are sensitive to helical integrity. The new alanines, A5 and A19, therefore, provide new information about the length of the core helix and the onset of unraveling of the terminals. Residue A19 remains essentially on the central helix in each lipid membrane, while residues A3, A5 and A21 deviate from the core helix to an extent that depends on the membrane thickness. Differential unraveling of the two ends to expose peptide backbone groups for hydrogen bonding therefore acts together with specific interfacial side chains to stabilize a transmembrane helix.
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29
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Correia C, Xavier CPR, Duarte D, Ferreira A, Moreira S, Vasconcelos MH, Vale N. Development of potent CPP6-gemcitabine conjugates against human prostate cancer cell line (PC-3). RSC Med Chem 2020; 11:268-273. [PMID: 33479633 DOI: 10.1039/c9md00489k] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 12/31/2019] [Indexed: 01/19/2023] Open
Abstract
Gemcitabine (dFdC) is a nucleoside analogue used in the treatment of various cancers, being a standard treatment for advanced pancreatic cancer. The effect of gemcitabine is severely compromised due to its rapid plasma degradation, systemic toxicity and drug resistance, which restricts its therapeutic efficacy. Our main goal was to develop new active conjugates of dFdC with novel cell-penetrating hexapeptides (CPP6) to facilitate intracellular delivery of this drug. All new peptides were prepared by solid phase peptide synthesis (SPPS), purified and characterized by HPLC and LC-MS. Cell-penetrating peptides (CPP) contain a considerably high ratio of positively charged amino acids, imparting them with cationic character. Tumor cells are characterized by an increased anionic nature of their membrane surface, a property that could be used by CPP to target these cells. The BxPC-3, MCF-7 and PC-3 cancer cell lines were used to evaluate the in vitro cytotoxicity of conjugates and the results showed that conjugating dFdC with CPP6 significantly enhanced cell growth inhibitory activity on PC-3 cells, with IC50 between 14 and 15 nM. These new conjugates have potential to become new therapeutic tools for cancer therapy.
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Affiliation(s)
- Cristiana Correia
- Laboratory of Pharmacology , Department of Drug Sciences , Faculty of Pharmacy , University of Porto , Rua de Jorge Viterbo Ferreira 228 , 4050-313 Porto , Portugal . .,Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP) , Rua Júlio Amaral de Carvalho , 45 , 4200-135 Porto , Portugal.,Instituto de Investigação e Inovação em Saúde (i3S) , University of Porto , Rua Alfredo Allen, 208 , 4200-135 Porto , Portugal
| | - Cristina P R Xavier
- Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP) , Rua Júlio Amaral de Carvalho , 45 , 4200-135 Porto , Portugal.,Instituto de Investigação e Inovação em Saúde (i3S) , University of Porto , Rua Alfredo Allen, 208 , 4200-135 Porto , Portugal
| | - Diana Duarte
- Laboratory of Pharmacology , Department of Drug Sciences , Faculty of Pharmacy , University of Porto , Rua de Jorge Viterbo Ferreira 228 , 4050-313 Porto , Portugal . .,Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP) , Rua Júlio Amaral de Carvalho , 45 , 4200-135 Porto , Portugal.,Instituto de Investigação e Inovação em Saúde (i3S) , University of Porto , Rua Alfredo Allen, 208 , 4200-135 Porto , Portugal
| | - Abigail Ferreira
- Laboratory of Pharmacology , Department of Drug Sciences , Faculty of Pharmacy , University of Porto , Rua de Jorge Viterbo Ferreira 228 , 4050-313 Porto , Portugal . .,LAQV/REQUIMTE , Department of Chemical Sciences , Faculty of Pharmacy , University of Porto , Rua de Jorge Viterbo Ferreira 228 , 4050-313 Porto , Portugal
| | - Sara Moreira
- Laboratory of Pharmacology , Department of Drug Sciences , Faculty of Pharmacy , University of Porto , Rua de Jorge Viterbo Ferreira 228 , 4050-313 Porto , Portugal . .,Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP) , Rua Júlio Amaral de Carvalho , 45 , 4200-135 Porto , Portugal.,Instituto de Investigação e Inovação em Saúde (i3S) , University of Porto , Rua Alfredo Allen, 208 , 4200-135 Porto , Portugal
| | - M Helena Vasconcelos
- Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP) , Rua Júlio Amaral de Carvalho , 45 , 4200-135 Porto , Portugal.,Instituto de Investigação e Inovação em Saúde (i3S) , University of Porto , Rua Alfredo Allen, 208 , 4200-135 Porto , Portugal.,Laboratory of Microbiology , Department of Biological Sciences , Faculty of Pharmacy , University of Porto , Rua de Jorge Viterbo Ferreira, 228 , 4050-313 Porto , Portugal
| | - Nuno Vale
- Laboratory of Pharmacology , Department of Drug Sciences , Faculty of Pharmacy , University of Porto , Rua de Jorge Viterbo Ferreira 228 , 4050-313 Porto , Portugal . .,Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP) , Rua Júlio Amaral de Carvalho , 45 , 4200-135 Porto , Portugal.,Instituto de Investigação e Inovação em Saúde (i3S) , University of Porto , Rua Alfredo Allen, 208 , 4200-135 Porto , Portugal.,Department of Molecular Pathology and Immunology , Abel Salazar Biomedical Sciences Institute (ICBAS) , University of Porto , Rua de Jorge Viterbo Ferreira 228 , 4050-313 Porto , Portugal
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30
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Kubyshkin V, Grage SL, Ulrich AS, Budisa N. Bilayer thickness determines the alignment of model polyproline helices in lipid membranes. Phys Chem Chem Phys 2019; 21:22396-22408. [PMID: 31577299 DOI: 10.1039/c9cp02996f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Our understanding of protein folds relies fundamentally on the set of secondary structures found in the proteomes. Yet, there also exist intriguing structures and motifs that are underrepresented in natural biopolymeric systems. One example is the polyproline II helix, which is usually considered to have a polar character and therefore does not form membrane spanning sections of membrane proteins. In our work, we have introduced specially designed polyproline II helices into the hydrophobic membrane milieu and used 19F NMR to monitor the helix alignment in oriented lipid bilayers. Our results show that these artificial hydrophobic peptides can adopt several different alignment states. If the helix is shorter than the thickness of the hydrophobic core of the membrane, it is submerged into the bilayer with its long axis parallel to the membrane plane. The polyproline helix adopts a transmembrane alignment when its length exceeds the bilayer thickness. If the peptide length roughly matches the lipid thickness, a coexistence of both states is observed. We thus show that the lipid thickness plays a determining role in the occurrence of a transmembrane polyproline II helix. We also found that the adaptation of polyproline II helices to hydrophobic mismatch is in some notable aspects different from α-helices. Finally, our results prove that the polyproline II helix is a competent structure for the construction of transmembrane peptide segments, despite the fact that no such motif has ever been reported in natural systems.
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Affiliation(s)
- Vladimir Kubyshkin
- Institute of Chemistry, Technical University of Berlin, Müller-Breslau-Str. 10, Berlin 10623, Germany and Department of Chemistry, University of Manitoba, Dysart Rd. 144, Winnipeg MB R3T 2N2, Canada.
| | - Stephan L Grage
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology (KIT), P.O.B. 3640, Karlsruhe 76021, Germany
| | - Anne S Ulrich
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology (KIT), P.O.B. 3640, Karlsruhe 76021, Germany and Institute of Organic Chemistry, KIT, Fritz-Haber-Weg 6, Karlsruhe 76131, Germany
| | - Nediljko Budisa
- Institute of Chemistry, Technical University of Berlin, Müller-Breslau-Str. 10, Berlin 10623, Germany and Department of Chemistry, University of Manitoba, Dysart Rd. 144, Winnipeg MB R3T 2N2, Canada.
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31
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Jiang Y, Dai X, Qin M, Guo Z. Identification of an amphipathic peptide sensor of the Bacillus subtilis fluid membrane microdomains. Commun Biol 2019; 2:316. [PMID: 31453380 PMCID: PMC6702220 DOI: 10.1038/s42003-019-0562-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Accepted: 07/29/2019] [Indexed: 01/26/2023] Open
Abstract
Regions of increased fluidity are newly found bacterial membrane microdomains that are composed of short, unsaturated and branched fatty acyl chains in a fluid and disordered state. Currently, little is known about how proteins are recruited and localized to these membrane domains. Here, we identify a short amphipathic α-peptide in a previously unreported crystal structure and show that it is responsible for peripheral localization of the phosphate acyltransferase PlsX to the fluid microdomains in Bacillus subtilis. Mutations disrupting the amphipathic interaction or increasing the nonpolar interaction are found to redistribute the protein to the cytosol or other part of the plasma membrane, causing growth defects. These results reveal a mechanism of peripheral membrane sensing through optimizing nonpolar interaction with the special lipids in the microdomains. This finding shows that the fluid membrane microdomains may take advantage of their unique lipid environment as a means of recruiting and organizing proteins.
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Affiliation(s)
- Yiping Jiang
- Shenzhen Research Institute and Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR China
| | - Xin Dai
- Shenzhen Research Institute and Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR China
| | - Mingming Qin
- Shenzhen Research Institute and Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR China
| | - Zhihong Guo
- Shenzhen Research Institute and Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR China
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32
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Kulandaisamy A, Priya SB, Sakthivel R, Frishman D, Gromiha MM. Statistical analysis of disease‐causing and neutral mutations in human membrane proteins. Proteins 2019; 87:452-466. [DOI: 10.1002/prot.25667] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 01/16/2019] [Accepted: 01/31/2019] [Indexed: 11/11/2022]
Affiliation(s)
- A. Kulandaisamy
- Department of Biotechnology, Bhupat and Jyoti Mehta School of BiosciencesIndian Institute of Technology Madras Chennai Tamil Nadu India
| | - S. Binny Priya
- Department of Biotechnology, Bhupat and Jyoti Mehta School of BiosciencesIndian Institute of Technology Madras Chennai Tamil Nadu India
| | - R. Sakthivel
- Department of Biotechnology, Bhupat and Jyoti Mehta School of BiosciencesIndian Institute of Technology Madras Chennai Tamil Nadu India
| | - Dmitrij Frishman
- Department of BioinformaticsPeter the Great St. Petersburg Polytechnic University St. Petersburg Russian Federation
- Department of BioinformaticsTechnische Universität München, Wissenschaftszentrum Weihenstephan Freising Germany
| | - M. Michael Gromiha
- Department of Biotechnology, Bhupat and Jyoti Mehta School of BiosciencesIndian Institute of Technology Madras Chennai Tamil Nadu India
- Advanced Computational Drug Discovery Unit (ACDD)Institute of Innovative Research, Tokyo Institute of Technology Yokohama Kanagawa Japan
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33
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Olšinová M, Jurkiewicz P, Kishko I, Sýkora J, Sabó J, Hof M, Cwiklik L, Cebecauer M. Roughness of Transmembrane Helices Reduces Lipid Membrane Dynamics. iScience 2018; 10:87-97. [PMID: 30508721 PMCID: PMC6277224 DOI: 10.1016/j.isci.2018.11.026] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 10/23/2018] [Accepted: 11/14/2018] [Indexed: 01/23/2023] Open
Abstract
The dynamics of cellular membranes is primarily determined by lipid species forming a bilayer. Proteins are considered mainly as effector molecules of diverse cellular processes. In addition to large assemblies of proteins, which were found to influence properties of fluid membranes, biological membranes are densely populated by small, highly mobile proteins. However, little is known about the effect of such proteins on the dynamics of membranes. Using synthetic peptides, we demonstrate that transmembrane helices interfere with the mobility of membrane components by trapping lipid acyl chains on their rough surfaces. The effect is more pronounced in the presence of cholesterol, which segregates from the rough surface of helical peptides. This may contribute to the formation or stabilization of membrane heterogeneities. Since roughness is a general property of helical transmembrane segments, our results suggest that, independent of their size or cytoskeleton linkage, integral membrane proteins affect local membrane dynamics and organization.
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Affiliation(s)
- Marie Olšinová
- Department of Biophysical Chemistry, J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, 182 23 Prague, Czech Republic
| | - Piotr Jurkiewicz
- Department of Biophysical Chemistry, J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, 182 23 Prague, Czech Republic
| | - Iryna Kishko
- Department of Biophysical Chemistry, J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, 182 23 Prague, Czech Republic
| | - Jan Sýkora
- Department of Biophysical Chemistry, J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, 182 23 Prague, Czech Republic
| | - Ján Sabó
- Department of Biophysical Chemistry, J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, 182 23 Prague, Czech Republic
| | - Martin Hof
- Department of Biophysical Chemistry, J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, 182 23 Prague, Czech Republic
| | - Lukasz Cwiklik
- Department of Theoretical Chemistry, J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, 182 23 Prague, Czech Republic
| | - Marek Cebecauer
- Department of Biophysical Chemistry, J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, 182 23 Prague, Czech Republic.
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34
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Pazos M, Peters K, Casanova M, Palacios P, VanNieuwenhze M, Breukink E, Vicente M, Vollmer W. Z-ring membrane anchors associate with cell wall synthases to initiate bacterial cell division. Nat Commun 2018; 9:5090. [PMID: 30504892 PMCID: PMC6269477 DOI: 10.1038/s41467-018-07559-2] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 11/08/2018] [Indexed: 12/29/2022] Open
Abstract
During the transition from elongation to septation, Escherichia coli establishes a ring-like peptidoglycan growth zone at the future division site. This preseptal peptidoglycan synthesis does not require the cell division-specific peptidoglycan transpeptidase PBP3 or most of the other cell division proteins, but it does require FtsZ, its membrane-anchor ZipA and at least one of the bi-functional transglycosylase-transpeptidases, PBP1A or PBP1B. Here we show that PBP1A and PBP1B interact with ZipA and localise to preseptal sites in cells with inhibited PBP3. ZipA stimulates the glycosyltransferase activity of PBP1A. The membrane-anchored cell division protein FtsN localises at preseptal sites and stimulates both activities of PBP1B. Genes zipA and ftsN can be individually deleted in ftsA* mutant cells, but the simultaneous depletion of both proteins is lethal and cells do not establish preseptal sites. Our data support a model according to which ZipA and FtsN-FtsA have semi-redundant roles in connecting the cytosolic FtsZ ring with the membrane-anchored peptidoglycan synthases during the preseptal phase of envelope growth. Proteins FtsZ, ZipA, and either PBP1A or PBP1B are required for the synthesis of preseptal peptidoglycan at the future cell division site in E. coli. Here, Pazos et al. provide evidence that ZipA and FtsA-FtsN connect the cytosolic FtsZ ring with the membrane-anchored PBPs.
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Affiliation(s)
- Manuel Pazos
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX, UK
| | - Katharina Peters
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX, UK
| | - Mercedes Casanova
- Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC), Darwin 3, 28049, Madrid, Spain
| | - Pilar Palacios
- Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC), Darwin 3, 28049, Madrid, Spain
| | - Michael VanNieuwenhze
- Molecular and Cellular Biochemistry Department, Biology Department, Indiana University, 212S. Hawthorne Dr, Bloomington, IN, 47405, USA
| | - Eefjan Breukink
- Membrane Biochemistry and Biophysics, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Miguel Vicente
- Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC), Darwin 3, 28049, Madrid, Spain
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX, UK.
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35
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Lee MY, Park SC, Jung M, Shin MK, Kang HL, Baik SC, Cheong GW, Jang MK, Lee WK. Cell-selectivity of tryptophan and tyrosine in amphiphilic α-helical antimicrobial peptides against drug-resistant bacteria. Biochem Biophys Res Commun 2018; 505:478-484. [PMID: 30268502 DOI: 10.1016/j.bbrc.2018.09.095] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 09/14/2018] [Indexed: 12/18/2022]
Abstract
The increasing emergence of drug-resistant bacteria creates a requirement for new antibiotics and various types of antibiotic materials such as proteins, peptides, polymers, and chemical compounds. Among these, antimicrobial peptides (AMPs) are considered to be promising antibiotic candidates for clinical treatments. In this study, we have designed a novel series of peptides with repeated sequences of minimum membrane-active motif, 'XWZX' basic sequence (X: lysine or arginine, Z: leucine, tyrosine, valine, or glycine), and an α-helical secondary structure. Some peptides displayed a potent antibacterial activity via membranolytic action and high therapeutic index (toxic dose/minimum inhibitory concentration) in vitro. Furthermore, in vivo experiments using bacterial ear-skin infection models verified that these peptides have the potential to be powerful and safe antibiotics. The present study provides a lead sequence for designing peptide antibiotics against bacterial membranes and information for cell-selectivity of hydrophobic amino acids with aromatic side chains such as Trp and Tyr.
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Affiliation(s)
- Min-Young Lee
- Department of Microbiology, Gyeongsang National University School of Medicine, Jinju, Gyeongnam, 52727, South Korea
| | - Seong-Cheol Park
- Department of Polymer Science and Engineering, Sunchon National University, Suncheon, Jeonnam, 57922, South Korea
| | - Myunghwan Jung
- Department of Microbiology, Gyeongsang National University School of Medicine, Jinju, Gyeongnam, 52727, South Korea
| | - Min-Kyoung Shin
- Department of Microbiology, Gyeongsang National University School of Medicine, Jinju, Gyeongnam, 52727, South Korea
| | - Hyung-Lyun Kang
- Department of Microbiology, Gyeongsang National University School of Medicine, Jinju, Gyeongnam, 52727, South Korea
| | - Seung-Chul Baik
- Department of Microbiology, Gyeongsang National University School of Medicine, Jinju, Gyeongnam, 52727, South Korea
| | - Gang-Won Cheong
- Division of Applied Life Sciences and Research Institute of Natural Science, Gyeongsang National University, Jinju, Gyeongnam, 52828, South Korea
| | - Mi-Kyeong Jang
- Department of Polymer Science and Engineering, Sunchon National University, Suncheon, Jeonnam, 57922, South Korea; The Research Institute for Sanitation and Environment of Coastal Areas, Sunchon National University, Suncheon, Jeonnam, 57922, South Korea.
| | - Woo-Kon Lee
- Department of Microbiology, Gyeongsang National University School of Medicine, Jinju, Gyeongnam, 52727, South Korea.
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36
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Pal S, Koeppe RE, Chattopadhyay A. Wavelength-Selective Fluorescence of a Model Transmembrane Peptide: Constrained Dynamics of Interfacial Tryptophan Anchors. J Fluoresc 2018; 28:1317-1323. [PMID: 30225736 DOI: 10.1007/s10895-018-2293-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 09/03/2018] [Indexed: 11/27/2022]
Abstract
WALPs are prototypical, α-helical transmembrane peptides that represent a consensus sequence for transmembrane segments of integral membrane proteins and serve as excellent models for exploring peptide-lipid interactions and hydrophobic mismatch in membranes. Importantly, the WALP peptides are in direct contact with the lipids. They consist of a central stretch of alternating hydrophobic alanine and leucine residues capped at both ends by tryptophans. In this work, we employ wavelength-selective fluorescence approaches to explore the intrinsic fluorescence of tryptophan residues in WALP23 in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) membranes. Our results show that the four tryptophan residues in WALP23 exhibit an average red edge excitation shift (REES) of 6 nm, implying their localization at the membrane interface, characterized by a restricted microenvironment. This result is supported by fluorescence anisotropy and lifetime measurements as a function of wavelength displayed by WALP23 tryptophans in POPC membranes. These results provide a new approach based on intrinsic fluorescence of interfacial tryptophans to address protein-lipid interaction and hydrophobic mismatch.
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Affiliation(s)
- Sreetama Pal
- CSIR-Indian Institute of Chemical Technology, Uppal Road, Hyderabad, 500 007, India
- Academy of Scientific and Innovative Research, Ghaziabad, India
| | - Roger E Koeppe
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR, 72701, USA
| | - Amitabha Chattopadhyay
- Academy of Scientific and Innovative Research, Ghaziabad, India.
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500 007, India.
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37
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Weaver JC, Krilis SA, Giannakopoulos B. Oxidative post-translational modification of βeta 2-glycoprotein I in the pathophysiology of the anti-phospholipid syndrome. Free Radic Biol Med 2018; 125:98-103. [PMID: 29604397 DOI: 10.1016/j.freeradbiomed.2018.03.048] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 03/23/2018] [Accepted: 03/28/2018] [Indexed: 12/13/2022]
Abstract
The anti-phospholipid syndrome (APS) is a prothrombotic autoimmune disorder characterized by either thrombosis or pregnancy complications in the setting of persistent anti-phospholipid antibodies (aPL). βeta 2-glycoprotein I (β2-GPI) is the major autoantigen in APS that binds anionic phospholipids as well as specific receptors on platelets and endothelial cells resulting in activation of prothrombotic pathways. β2-GPI consists of 5 Domains that exist in a circular or linear form, with the latter occurring after binding to anionic phospholipids. β2-GPI also undergoes dynamic posttranslational modification between oxidized and free thiol forms. The relationship between posttranslational modification and structural conformation is yet to be definitively clarified. Compared with controls, patients with the APS have higher levels of total β2-GPI and lower levels of free thiol β2-GPI. This raises the possibility of using quantification of β2-GPI posttranslational modification as a redox biomarker in the management and diagnosis of the APS.
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Affiliation(s)
- James C Weaver
- Department of Cardiology, St George Hospital, Sydney, Australia; Department of Medicine, University of NSW, Sydney, Australia
| | - Steven A Krilis
- Department of Medicine, University of NSW, Sydney, Australia; Department of Infectious Diseases, Immunology and Sexual Health, St George Hospital, Sydney, Australia
| | - Bill Giannakopoulos
- Department of Medicine, University of NSW, Sydney, Australia; Department of Infectious Diseases, Immunology and Sexual Health, St George Hospital, Sydney, Australia; Department of Rheumatology, St George Hospital, Sydney, Australia.
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38
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McKay MJ, Martfeld AN, De Angelis AA, Opella SJ, Greathouse DV, Koeppe RE. Control of Transmembrane Helix Dynamics by Interfacial Tryptophan Residues. Biophys J 2018; 114:2617-2629. [PMID: 29874612 PMCID: PMC6129553 DOI: 10.1016/j.bpj.2018.04.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 04/06/2018] [Accepted: 04/11/2018] [Indexed: 01/12/2023] Open
Abstract
Transmembrane protein domains often contain interfacial aromatic residues, which may play a role in the insertion and stability of membrane helices. Residues such as Trp or Tyr, therefore, are often found situated at the lipid-water interface. We have examined the extent to which the precise radial locations of interfacial Trp residues may influence peptide helix orientation and dynamics. To address these questions, we have modified the GW5,19ALP23 (acetyl-GGALW5(LA)6LW19LAGA-[ethanol]amide) model peptide framework to relocate the Trp residues. Peptide orientation and dynamics were analyzed by means of solid-state nuclear magnetic resonance (NMR) spectroscopy to monitor specific 2H- and 15N-labeled residues. GW5,19ALP23 adopts a defined, tilted orientation within lipid bilayer membranes with minimal evidence of motional averaging of NMR observables, such as 2H quadrupolar or 15N-1H dipolar splittings. Here, we examine how peptide dynamics are impacted by relocating the interfacial Trp (W) residues on both ends and opposing faces of the helix, for example by a 100° rotation on the helical wheel for positions 4 and 20. In contrast to GW5,19ALP23, the modified GW4,20ALP23 helix experiences more extensive motional averaging of the NMR observables in several lipid bilayers of different thickness. Individual and combined Gaussian analyses of the 2H and 15N NMR signals confirm that the extent of dynamic averaging, particularly rotational "slippage" about the helix axis, is strongly coupled to the radial distribution of the interfacial Trp residues as well as the bilayer thickness. Additional 2H labels on alanines A3 and A21 reveal partial fraying of the helix ends. Even within the context of partial unwinding, the locations of particular Trp residues around the helix axis are prominent factors for determining transmembrane helix orientation and dynamics within the lipid membrane environment.
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Affiliation(s)
- Matthew J McKay
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas
| | - Ashley N Martfeld
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas
| | - Anna A De Angelis
- Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, California
| | - Stanley J Opella
- Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, California
| | - Denise V Greathouse
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas
| | - Roger E Koeppe
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas.
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39
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Warfarin and vitamin K epoxide reductase: a molecular accounting for observed inhibition. Blood 2018; 132:647-657. [PMID: 29743176 DOI: 10.1182/blood-2018-01-830901] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 05/06/2018] [Indexed: 01/05/2023] Open
Abstract
Vitamin K epoxide reductase (VKOR), an endoplasmic reticulum membrane protein, is the key enzyme for vitamin K-dependent carboxylation, a posttranslational modification that is essential for the biological functions of coagulation factors. VKOR is the target of the most widely prescribed oral anticoagulant, warfarin. However, the topological structure of VKOR and the mechanism of warfarin's inhibition of VKOR remain elusive. Additionally, it is not clear why warfarin-resistant VKOR mutations identified in patients significantly decrease warfarin's binding affinity, but have only a minor effect on vitamin K binding. Here, we used immunofluorescence confocal imaging of VKOR in live mammalian cells and PEGylation of VKOR's endogenous cytoplasmic-accessible cysteines in intact microsomes to probe the membrane topology of human VKOR. Our results show that the disputed loop sequence between the first and second transmembrane (TM) domain of VKOR is located in the cytoplasm, supporting a 3-TM topological structure of human VKOR. Using molecular dynamics (MD) simulations, a T-shaped stacking interaction between warfarin and tyrosine residue 139, within the proposed TY139A warfarin-binding motif, was observed. Furthermore, a reversible dynamic warfarin-binding pocket opening and conformational changes were observed when warfarin binds to VKOR. Several residues (Y25, A26, and Y139) were found essential for warfarin binding to VKOR by MD simulations, and these were confirmed by the functional study of VKOR and its mutants in their native milieu using a cell-based assay. Our findings provide new insights into the dynamics of the binding of warfarin to VKOR, as well as into warfarin's mechanism of anticoagulation.
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40
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Nakao H, Hayashi C, Ikeda K, Saito H, Nagao H, Nakano M. Effects of Hydrophilic Residues and Hydrophobic Length on Flip-Flop Promotion by Transmembrane Peptides. J Phys Chem B 2018; 122:4318-4324. [PMID: 29589918 DOI: 10.1021/acs.jpcb.8b00298] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Peptide-induced phospholipid flip-flop (scrambling) was evaluated using transmembrane model peptides in which the central residue was substituted with various amino acid residues (sequence: Ac-GKK(LA) nXW(LA) nLKKA-CONH2). Peptides with a strongly hydrophilic residue (X = Q, N, or H) had higher scramblase activity than that of other peptides, and the activity was also dependent on the length of the peptides. Peptides with a hydrophobic stretch of 17 residues showed high flip-promotion propensity, whereas those of 21 and 25 residues did not, suggesting that membrane thinning under negative mismatch conditions promotes the flipping. Interestingly, a hydrophobic stretch of 19 residues intensively promoted phospholipid scrambling and membrane leakage. The distinctive characteristics of the peptide were ascribed by long-term molecular dynamics simulation to the arrangement of central glutamine and terminal four lysine residues on the same side of the helix. The combination of simulated and experimental data enables understanding of the mechanisms by which transmembrane helices, and ultimately unidentified scramblases in biomembranes, cause lipid scrambling.
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Affiliation(s)
- Hiroyuki Nakao
- Graduate School of Medicine and Pharmaceutical Sciences , University of Toyama , 2630 Sugitani , Toyama 930-0194 , Japan
| | - Chihiro Hayashi
- Graduate School of Medicine and Pharmaceutical Sciences , University of Toyama , 2630 Sugitani , Toyama 930-0194 , Japan
| | - Keisuke Ikeda
- Graduate School of Medicine and Pharmaceutical Sciences , University of Toyama , 2630 Sugitani , Toyama 930-0194 , Japan
| | - Hiroaki Saito
- Institute of Science and Engineering , Kanazawa University , Kakuma , Kanazawa , Ishikawa 920-1192 , Japan.,Laboratory for Computational Molecular Design , RIKEN Quantitative Biology Center , 6-2-4 Furuedai , Suita , Osaka 565-0874 , Japan
| | - Hidemi Nagao
- Institute of Science and Engineering , Kanazawa University , Kakuma , Kanazawa , Ishikawa 920-1192 , Japan
| | - Minoru Nakano
- Graduate School of Medicine and Pharmaceutical Sciences , University of Toyama , 2630 Sugitani , Toyama 930-0194 , Japan
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41
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Zhang J, Yang W, Tan J, Ye S. In situ examination of a charged amino acid-induced structural change in lipid bilayers by sum frequency generation vibrational spectroscopy. Phys Chem Chem Phys 2018; 20:5657-5665. [PMID: 29412195 DOI: 10.1039/c7cp07389e] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The interactions between amino acids (AAs) and membranes represent various short-range and long-range interactions for biological phenomena; however, they are still poorly understood. In this study, we used cationic lysine and arginine as AA models, and systematically investigated the interactions between charged AAs and lipid bilayers using sum frequency generation vibrational spectroscopy (SFG-VS) in situ and in real time. The AA-induced dynamic structural changes of the lipid bilayer were experimentally monitored using the spectral features of CD2, CD3, the lipid head phosphate, and carbonyl groups in real time. Time-dependent SFG changes in the structure of the lipid bilayer provide direct evidence for the different interactions of lysine and arginine with the membrane. It was found that the discrepancy between lysine and arginine in binding with the lipid bilayer is due to the nature of the terminal functional groups. Arginine exhibits a more drastic impact on the membrane than lysine. SFG responses of the acyl chains, phosphate groups, and carbonyl groups provide evidence that the interaction between AAs and the membrane most likely follows an electrostatics and hydrogen bond-induced defect model. This work presents an exemplary method for comprehensive investigations of interactions between membranes and other functionally significant substances.
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Affiliation(s)
- Jiahui Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale, and Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
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42
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McKay MJ, Afrose F, Koeppe RE, Greathouse DV. Helix formation and stability in membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:2108-2117. [PMID: 29447916 DOI: 10.1016/j.bbamem.2018.02.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 02/06/2018] [Accepted: 02/07/2018] [Indexed: 01/05/2023]
Abstract
In this article we review current understanding of basic principles for the folding of membrane proteins, focusing on the more abundant alpha-helical class. Membrane proteins, vital to many biological functions and implicated in numerous diseases, fold into their active conformations in the complex environment of the cell bilayer membrane. While many membrane proteins rely on the translocon and chaperone proteins to fold correctly, others can achieve their functional form in the absence of any translation apparatus or other aides. Nevertheless, the spontaneous folding process is not well understood at the molecular level. Recent findings suggest that helix fraying and loop formation may be important for overall structure, dynamics and regulation of function. Several types of membrane helices with ionizable amino acids change their topology with pH. Additionally we note that some peptides, including many that are rich in arginine, and a particular analogue of gramicidin, are able passively to translocate across cell membranes. The findings indicate that a final protein structure in a lipid-bilayer membrane is sequence-based, with lipids contributing to stability and regulation. While much progress has been made toward understanding the folding process for alpha-helical membrane proteins, it remains a work in progress. This article is part of a Special Issue entitled: Emergence of Complex Behavior in Biomembranes edited by Marjorie Longo.
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Affiliation(s)
- Matthew J McKay
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA
| | - Fahmida Afrose
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA
| | - Roger E Koeppe
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA
| | - Denise V Greathouse
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA.
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43
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Biondi B, Peggion C, De Zotti M, Pignaffo C, Dalzini A, Bortolus M, Oancea S, Hilma G, Bortolotti A, Stella L, Pedersen JZ, Syryamina VN, Tsvetkov YD, Dzuba SA, Toniolo C, Formaggio F. Conformational properties, membrane interaction, and antibacterial activity of the peptaibiotic chalciporin A: Multitechnique spectroscopic and biophysical investigations on the natural compound and labeled analogs. Biopolymers 2017; 110. [PMID: 29127716 DOI: 10.1002/bip.23083] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 10/06/2017] [Accepted: 10/15/2017] [Indexed: 02/28/2024]
Abstract
In this work, an extensive set of spectroscopic and biophysical techniques (including FT-IR absorption, CD, 2D-NMR, fluorescence, and CW/PELDOR EPR) was used to study the conformational preferences, membrane interaction, and bioactivity properties of the naturally occurring synthetic 14-mer peptaibiotic chalciporin A, characterized by a relatively low (≈20%), uncommon proportion of the strongly helicogenic Aib residue. In addition to the unlabeled peptide, we gained in-depth information from the study of two labeled analogs, characterized by one or two residues of the helicogenic, nitroxyl radical-containing TOAC. All three compounds were prepared using the SPPS methodology, which was carefully modified in the course of the syntheses of TOAC-labeled analogs in view of the poorly reactive α-amino function of this very bulky residue and the specific requirements of its free-radical side chain. Despite its potentially high flexibility, our results point to a predominant, partly amphiphilic, α-helical conformation for this peptaibiotic. Therefore, not surprisingly, we found an effective membrane affinity and a remarkable penetration propensity. However, chalciporin A exhibits a selectivity in its antibacterial activity not in agreement with that typical of the other members of this peptide class.
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Affiliation(s)
- Barbara Biondi
- Institute of Biomolecular, Chemistry, Padova Unit, CNR, Padova, 35131, Italy
| | - Cristina Peggion
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
| | - Marta De Zotti
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
| | - Chiara Pignaffo
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
| | - Annalisa Dalzini
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
| | - Marco Bortolus
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
| | - Simona Oancea
- Department of Agricultural Sciences and Food Engineering, "Lucian Blaga" University of Sibiu, Sibiu, 550012, Romania
| | - Geta Hilma
- Department of Medicine, "Lucian Blaga" University of Sibiu, Sibiu, 550012, Romania
| | - Annalisa Bortolotti
- Department of Chemical Sciences and Technologies, University of Rome Tor Vergata, Rome, 00133, Italy
| | - Lorenzo Stella
- Department of Chemical Sciences and Technologies, University of Rome Tor Vergata, Rome, 00133, Italy
| | - Jens Z Pedersen
- Department of Biology, University of Rome Tor Vergata, Rome, 00133, Italy
| | - Victoria N Syryamina
- Institute of Chemical Kinetics and Combustion, Novosibirsk, 630090, Russian Federation
| | - Yuri D Tsvetkov
- Institute of Chemical Kinetics and Combustion, Novosibirsk, 630090, Russian Federation
| | - Sergei A Dzuba
- Institute of Chemical Kinetics and Combustion, Novosibirsk, 630090, Russian Federation
| | - Claudio Toniolo
- Institute of Biomolecular, Chemistry, Padova Unit, CNR, Padova, 35131, Italy
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
| | - Fernando Formaggio
- Institute of Biomolecular, Chemistry, Padova Unit, CNR, Padova, 35131, Italy
- Department of Chemical Sciences, University of Padova, Padova, 35131, Italy
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44
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Jung A, Rajakumar D, Yoon BJ, Baker BJ. Modulating the Voltage-sensitivity of a Genetically Encoded Voltage Indicator. Exp Neurobiol 2017; 26:241-251. [PMID: 29093633 PMCID: PMC5661057 DOI: 10.5607/en.2017.26.5.241] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 08/19/2017] [Accepted: 09/24/2017] [Indexed: 11/19/2022] Open
Abstract
Saturation mutagenesis was performed on a single position in the voltage-sensing domain (VSD) of a genetically encoded voltage indicator (GEVI). The VSD consists of four transmembrane helixes designated S1-S4. The V220 position located near the plasma membrane/extracellular interface had previously been shown to affect the voltage range of the optical signal. Introduction of polar amino acids at this position reduced the voltage-dependent optical signal of the GEVI. Negatively charged amino acids slightly reduced the optical signal by 33 percent while positively charge amino acids at this position reduced the optical signal by 80%. Surprisingly, the range of V220D was similar to that of V220K with shifted optical responses towards negative potentials. In contrast, the V220E mutant mirrored the responses of the V220R mutation suggesting that the length of the side chain plays in role in determining the voltage range of the GEVI. Charged mutations at the 219 position all behaved similarly slightly shifting the optical response to more negative potentials. Charged mutations to the 221 position behaved erratically suggesting interactions with the plasma membrane and/or other amino acids in the VSD. Introduction of bulky amino acids at the V220 position increased the range of the optical response to include hyperpolarizing signals. Combining The V220W mutant with the R217Q mutation resulted in a probe that reduced the depolarizing signal and enhanced the hyperpolarizing signal which may lead to GEVIs that only report neuronal inhibition.
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Affiliation(s)
- Arong Jung
- The Center for Functional Connectomics, Korea Institute of Science and Technology, Seoul, Korea.,College of Life Sciences and Biotechnology, Korea University, Seoul, Korea
| | - Dhanarajan Rajakumar
- The Center for Functional Connectomics, Korea Institute of Science and Technology, Seoul, Korea
| | - Bong-June Yoon
- College of Life Sciences and Biotechnology, Korea University, Seoul, Korea
| | - Bradley J Baker
- The Center for Functional Connectomics, Korea Institute of Science and Technology, Seoul, Korea.,Division of Bio-Medical Science and Technology, KIST School, Korea University of Science and Technology (UST), Seoul, Korea
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45
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Trefz M, Keller R, Vogt M, Schneider D. The GlpF residue Trp219 is part of an amino-acid cluster crucial for aquaglyceroporin oligomerization and function. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:887-894. [PMID: 29069569 DOI: 10.1016/j.bbamem.2017.10.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 10/10/2017] [Accepted: 10/15/2017] [Indexed: 12/13/2022]
Abstract
The vestibule loop regions of aquaglyceroporins are involved in accumulation of glycerol inside the channel pore. Even though most loop regions do not show high sequence similarity among aquaglyceroporins, loop E is highly conserved in aquaglyceroporins, but not in members of the homologous aquaporins. Specifically, a tryptophan residue is extremely conserved within this loop. We have investigated the role of this residue (Trp219) that deeply protrudes into the protein and potentially interacts with adjacent loops, using the E. coli aqualgyeroporin GlpF as a model. Replacement of Trp219 affects the activity of GlpF and impairs the stability of the tetrameric protein. Furthermore, we have identified an amino acid cluster involving Trp219 that stabilizes the GlpF tetramer. Based on our results we propose that Trp219 is key for formation of a defined vestibule structure, which is crucial for glycerol accumulation as well as for the stability of the active GlpF tetramer.
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Affiliation(s)
- Margareta Trefz
- Johannes Gutenberg University, Johann-Joachim-Becher-Weg 30, 55128 Mainz, Germany
| | - Rebecca Keller
- Johannes Gutenberg University, Johann-Joachim-Becher-Weg 30, 55128 Mainz, Germany
| | - Miriam Vogt
- Johannes Gutenberg University, Johann-Joachim-Becher-Weg 30, 55128 Mainz, Germany
| | - Dirk Schneider
- Johannes Gutenberg University, Johann-Joachim-Becher-Weg 30, 55128 Mainz, Germany.
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46
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Lindner S, Gruhle K, Schmidt R, Garamus VM, Ramsbeck D, Hause G, Meister A, Sinz A, Drescher S. Azide-Modified Membrane Lipids: Synthesis, Properties, and Reactivity. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:4960-4973. [PMID: 28457130 DOI: 10.1021/acs.langmuir.7b00228] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In the present work, we describe the synthesis and the temperature-dependent behavior of photoreactive membrane lipids as well as their capability to study peptide/lipid interactions. The modified phospholipids contain an azide group either in the middle part or at the end of an alkyl chain and also differ in the linkage (ester vs ether) of the second alkyl chain. The temperature-dependent aggregation behavior of the azidolipids was studied using differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR) spectroscopy, and small-angle X-ray scattering (SAXS). Aggregate structures were visualized by stain and cryo transmission electron microscopy (TEM) and were further characterized by dynamic light scattering (DLS). We show that the position of the azide group and the type of linkage of the alkyl chain at the sn-2 position of the glycerol influences the type of aggregates formed as well as their long-term stability: P10AzSPC and r12AzSHPC show the formation of extrudable liposomes, which are stable in size during storage. In contrast, azidolipids that carry a terminal azido moiety either form extrudable liposomes, which show time-dependent vesicle fusion (P15AzPdPC), or self-assemble in large sheet-like, nonextrudable aggregates (r15AzPdHPC) where the lipid molecules are arranged in an interdigitated orientation at temperatures below Tm (LβI phase). Finally, a P10AzSPC:DMPC mixture was used for photochemically induced cross-linking experiments with a transmembrane peptide (WAL-peptide) to demonstrate the applicability of the azidolipids for the analysis of peptide/lipid interactions. The efficiency of photo-cross-linking was monitored by attenuated total reflection infrared (ATR-IR) spectroscopy and mass spectrometry (MS).
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Affiliation(s)
- Sindy Lindner
- Institute of Pharmacy - Pharmaceutical Chemistry and Bioanalytics, Martin Luther University (MLU) Halle-Wittenberg , Wolfgang-Langenbeck-Strasse 4, 06120 Halle (Saale), Germany
- Institute of Pharmacy - Biophysical Pharmacy, MLU Halle-Wittenberg , Wolfgang-Langenbeck-Strasse 4, 06120 Halle (Saale), Germany
| | - Kai Gruhle
- Institute of Pharmacy - Biophysical Pharmacy, MLU Halle-Wittenberg , Wolfgang-Langenbeck-Strasse 4, 06120 Halle (Saale), Germany
| | - Rico Schmidt
- Institute of Pharmacy - Pharmaceutical Chemistry and Bioanalytics, Martin Luther University (MLU) Halle-Wittenberg , Wolfgang-Langenbeck-Strasse 4, 06120 Halle (Saale), Germany
| | - Vasil M Garamus
- Helmholtz-Zentrum Geesthacht: Zentrum für Material und Küstenforschung GmbH (HZG), Max-Planck-Strasse 1, 21502 Geesthacht, Germany
| | - Daniel Ramsbeck
- Fraunhofer Institute for Cell Therapy and Immunology IZI , Weinbergweg 22, 06120 Halle (Saale), Germany
| | - Gerd Hause
- Biocenter, MLU Halle-Wittenberg , Weinbergweg 22, 06120 Halle (Saale), Germany
| | - Annette Meister
- Institute of Chemistry and Institute of Biochemistry and Biotechnology, MLU Halle-Wittenberg , von-Danckelmann-Platz 4, 06120 Halle (Saale), Germany
| | - Andrea Sinz
- Institute of Pharmacy - Pharmaceutical Chemistry and Bioanalytics, Martin Luther University (MLU) Halle-Wittenberg , Wolfgang-Langenbeck-Strasse 4, 06120 Halle (Saale), Germany
| | - Simon Drescher
- Institute of Pharmacy - Biophysical Pharmacy, MLU Halle-Wittenberg , Wolfgang-Langenbeck-Strasse 4, 06120 Halle (Saale), Germany
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47
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Transmembrane helices containing a charged arginine are thermodynamically stable. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2017; 46:627-637. [PMID: 28409218 DOI: 10.1007/s00249-017-1206-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 03/25/2017] [Accepted: 03/30/2017] [Indexed: 10/19/2022]
Abstract
Hydrophobic amino acids are abundant in transmembrane (TM) helices of membrane proteins. Charged residues are sparse, apparently due to the unfavorable energetic cost of partitioning charges into nonpolar phases. Nevertheless, conserved arginine residues within TM helices regulate vital functions, such as ion channel voltage gating and integrin receptor inactivation. The energetic cost of arginine in various positions along hydrophobic helices has been controversial. Potential of mean force (PMF) calculations from atomistic molecular dynamics simulations predict very large energetic penalties, while in vitro experiments with Sec61 translocons indicate much smaller penalties, even for arginine in the center of hydrophobic TM helices. Resolution of this conflict has proved difficult, because the in vitro assay utilizes the complex Sec61 translocon, while the PMF calculations rely on the choice of simulation system and reaction coordinate. Here we present the results of computational and experimental studies that permit direct comparison with the Sec61 translocon results. We find that the Sec61 translocon mediates less efficient membrane insertion of Arg-containing TM helices compared with our computational and experimental bilayer-insertion results. In the simulations, a combination of arginine snorkeling, bilayer deformation, and peptide tilting is sufficient to lower the penalty of Arg insertion to an extent such that a hydrophobic TM helix with a central Arg residue readily inserts into a model membrane. Less favorable insertion by the translocon may be due to the decreased fluidity of the endoplasmic reticulum (ER) membrane compared with pure palmitoyloleoyl-phosphocholine (POPC). Nevertheless, our results provide an explanation for the differences between PMF- and experiment-based penalties for Arg burial.
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Matthews JR, Shirazinejad CR, Isakson GA, Demers SME, Hafner JH. Structural Analysis by Enhanced Raman Scattering. NANO LETTERS 2017; 17:2172-2177. [PMID: 28166410 DOI: 10.1021/acs.nanolett.6b04509] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Gold nanostructures focus light to a molecular length scale at their surface, creating the possibility to visualize molecular structure. The high optical intensity leads to surface enhanced Raman scattering (SERS) from nearby molecules. SERS spectra contain information on molecular position and orientation relative to the surface but are difficult to interpret quantitatively. Here we describe a ratiometric analysis method that combines SERS and unenhanced Raman spectra with theoretical calculations of the optical field and molecular polarizability. When applied to the surfactant layer on gold nanorods, the alkane chain is found to be tilted 25° to the surface normal, which matches previous reports of the layer thickness. The analysis was also applied to fluid phase phospholipid bilayers that contain tryptophan on the surface of gold nanorods. The lipid double bond was found to be oriented normal to the bilayer and 13 Å from the nitrogen atom. Tryptophan was found to sit near the glycerol headgroup region with its indole ring 43° from the bilayer normal. This new method can determine specific interfacial structure under ambient conditions, with microscopic quantities of material, and without molecular labels.
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Affiliation(s)
- James R Matthews
- Department of Physics & Astronomy and ‡Department of Chemistry, Rice University , Houston, Texas 77251, United States
| | - Cyna R Shirazinejad
- Department of Physics & Astronomy and ‡Department of Chemistry, Rice University , Houston, Texas 77251, United States
| | - Grace A Isakson
- Department of Physics & Astronomy and ‡Department of Chemistry, Rice University , Houston, Texas 77251, United States
| | - Steven M E Demers
- Department of Physics & Astronomy and ‡Department of Chemistry, Rice University , Houston, Texas 77251, United States
| | - Jason H Hafner
- Department of Physics & Astronomy and ‡Department of Chemistry, Rice University , Houston, Texas 77251, United States
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Do guanidinium and tetrapropylammonium ions specifically interact with aromatic amino acid side chains? Proc Natl Acad Sci U S A 2017; 114:1003-1008. [PMID: 28096375 DOI: 10.1073/pnas.1618071114] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Many ions are known to affect the activity, stability, and structural integrity of proteins. Although this effect can be generally attributed to ion-induced changes in forces that govern protein folding, delineating the underlying mechanism of action still remains challenging because it requires assessment of all relevant interactions, such as ion-protein, ion-water, and ion-ion interactions. Herein, we use two unnatural aromatic amino acids and several spectroscopic techniques to examine whether guanidinium chloride, one of the most commonly used protein denaturants, and tetrapropylammonium chloride can specifically interact with aromatic side chains. Our results show that tetrapropylammonium, but not guanidinium, can preferentially accumulate around aromatic residues and that tetrapropylammonium undergoes a transition at ∼1.3 M to form aggregates. We find that similar to ionic micelles, on one hand, such aggregates can disrupt native hydrophobic interactions, and on the other hand, they can promote α-helix formation in certain peptides.
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Kocourková L, Novotná P, Čujová S, Čeřovský V, Urbanová M, Setnička V. Conformational study of melectin and antapin antimicrobial peptides in model membrane environments. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2017; 170:247-255. [PMID: 27450123 DOI: 10.1016/j.saa.2016.07.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 07/07/2016] [Indexed: 06/06/2023]
Abstract
Antimicrobial peptides have long been considered as promising compounds against drug-resistant pathogens. In this work, we studied the secondary structure of antimicrobial peptides melectin and antapin using electronic (ECD) and vibrational circular dichroism (VCD) spectroscopies that are sensitive to peptide secondary structures. The results from quantitative ECD spectral evaluation by Dichroweb and CDNN program and from the qualitative evaluation of the VCD spectra were compared. The antimicrobial activity of the selected peptides depends on their ability to adopt an amphipathic α-helical conformation on the surface of the bacterial membrane. Hence, solutions of different zwitterionic and negatively charged liposomes and micelles were used to mimic the eukaryotic and bacterial biological membranes. The results show a significant content of α-helical conformation in the solutions of negatively charged liposomes mimicking the bacterial membrane, thus correlating with the antimicrobial activity of the studied peptides. On the other hand in the solutions of zwitterionic liposomes used as models of the eukaryotic membranes, the fraction of α-helical conformation was lower, which corresponds with their moderate hemolytic activity.
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Affiliation(s)
- Lucie Kocourková
- Department of Analytical Chemistry, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6, Czech Republic
| | - Pavlína Novotná
- Department of Analytical Chemistry, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6, Czech Republic
| | - Sabína Čujová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo náměstí 2, 166 10 Prague 6, Czech Republic
| | - Václav Čeřovský
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo náměstí 2, 166 10 Prague 6, Czech Republic
| | - Marie Urbanová
- Department of Physics and Measurements, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6, Czech Republic
| | - Vladimír Setnička
- Department of Analytical Chemistry, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague 6, Czech Republic.
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