Ana Álvarez-Mena , Estelle Morvan , Denis Martinez , Melanie Berbon , Abigail Savietto Scholz , Axelle Grélard , Sarah Turpin , Erick J. Dufourc , Marc Bramkamp , Birgit Habenstein
{"title":"Bacterial flotillins as destabilizers of phospholipid membranes","authors":"Ana Álvarez-Mena , Estelle Morvan , Denis Martinez , Melanie Berbon , Abigail Savietto Scholz , Axelle Grélard , Sarah Turpin , Erick J. Dufourc , Marc Bramkamp , Birgit Habenstein","doi":"10.1016/j.bbamem.2024.184399","DOIUrl":"10.1016/j.bbamem.2024.184399","url":null,"abstract":"<div><div>From archaea to mammals evolutionary conserved flotillins are scaffolding proteins, recognized for their nandomain-segregating activity. Flotillins form basket-like oligomeric architectures on the membrane, based on a conserved secondary structure composition of the monomeric subunits: a membrane-targeting region, an SPFH domain and a coiled-coil “flotillin” domain. In <em>B. subtilis</em>, the two flotillins FloT and FloA are present, localizing mainly in distinct nanodomains and executing multiple cellular functions. We here use deuterium and phosphorus solid-state NMR to monitor the effect of the different flotillins FloT and FloA and their structural components on model membranes. We find a clear disordering effect of FloT and FloA on the membranes reaching the carbon positions in the centre of the membrane. This effect is imposed by the hydrophobic region and the adjacent SPFH domain and, surprisingly, further supported by the membrane-distant flotillin domain. Biological implications of this disordering action are discussed.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 1","pages":"Article 184399"},"PeriodicalIF":2.8,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142614074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Membrane fusion by dengue virus: The first step","authors":"José Villalaín","doi":"10.1016/j.bbamem.2024.184400","DOIUrl":"10.1016/j.bbamem.2024.184400","url":null,"abstract":"<div><div>Flaviviruses include important human pathogens such as Dengue, Zika, West Nile, Yellow fever, Japanese encephalitis, and Tick-borne encephalitis viruses as well as some emerging viruses that affect millions of people worldwide. They fuse their membrane with the late endosomal one in a pH-dependent way and therefore the merging of the membranes is one of the main goals for obtaining new antivirals. The envelope E protein, a membrane fusion protein, is accountable for fusion and encompasses different domains involved in the fusion mechanism, including the fusion peptide segment. In this work we have used molecular dynamics to study the interaction of the distal end of domain II of the DENV envelope E protein with a membrane like the late endosomal membrane in order to observe the initiation of membrane fusion carried out by a number of trimers of the DENV envelope E protein interacting with a complex biomembrane and demonstrate its feasibility. Our results demonstrate the likelihood of membrane disorganization and pore formation by trimer complex organization, the amino acids responsible for such condition and the secondary structure arrangements needed for such fundamental process. At the same time, we define new targets of the envelope E protein sequence which could permit designing potent antiviral bioactive molecules.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 1","pages":"Article 184400"},"PeriodicalIF":2.8,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142614096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Priya Patel , Swaleeha Jaan Abdullah , Kanchan Tiwari , Surajit Bhattacharjya , Kasturi Mukhopadhyay
{"title":"Antimicrobial and antibiofilm potential of α-MSH derived cationic and hydrophobic peptides against Escherichia coli: Mechanistic insight through peptide-lipopolysaccharide interactions","authors":"Priya Patel , Swaleeha Jaan Abdullah , Kanchan Tiwari , Surajit Bhattacharjya , Kasturi Mukhopadhyay","doi":"10.1016/j.bbamem.2024.184398","DOIUrl":"10.1016/j.bbamem.2024.184398","url":null,"abstract":"<div><div>The prevalence of infections caused by various Gram-negative pathogens specifically <em>Escherichia coli</em> continuously poses a significant challenge in health care as well as community settings owing to their ability to form biofilm and escalating tolerance towards available antibiotics. While most treatment regimes are targeted at eliminating the <em>E. coli</em> cells, the pathogenicity factors called endotoxin (lipopolysaccharides), associated with the sepsis initiation and the leading cause of death in intensive care units globally, are often ignored. In this study, the potency of alpha-melanocyte stimulating hormone based-peptides, particularly Ana-9 and Ana-10 against <em>E. coli</em> was investigated through microbiological, biophysical, and microscopic assays. Both Ana-9 and Ana-10 demonstrated enhanced activity against planktonic <em>E. coli</em> cells, and retained their activity against biofilm, which was supported by confocal microscopy. From the mechanistic perspective, spectroscopic studies indicated that the binding of peptides with LPS led to structural alteration of peptides due to their insertion into the hydrophobic environment of LPS. The electrostatic interaction of the peptide with LPS leads to outer membrane disorganization, allowing the peptide to access the inner membrane, depolarize it and ultimately inhibit the bacterial cells within the biofilm. These observations were further confirmed by atomic force and scanning electron microscopy. Thus, this study deepens our understanding of the structural characteristics of peptides attached to LPS, which could lead to the gradual improvement in developing more potent, broad-spectrum endotoxin neutralizers.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 1","pages":"Article 184398"},"PeriodicalIF":2.8,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142614066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Djuro Raskovic , Gloria Alvarado , Kelly M. Hines , Libin Xu , Craig Gatto , Brian J. Wilkinson , Antje Pokorny
{"title":"Growth of Staphylococcus aureus in the presence of oleic acid shifts the glycolipid fatty acid profile and increases resistance to antimicrobial peptides","authors":"Djuro Raskovic , Gloria Alvarado , Kelly M. Hines , Libin Xu , Craig Gatto , Brian J. Wilkinson , Antje Pokorny","doi":"10.1016/j.bbamem.2024.184395","DOIUrl":"10.1016/j.bbamem.2024.184395","url":null,"abstract":"<div><div><em>Staphylococcus aureus</em> readily adapts to various environments and quickly develops antibiotic resistance, which has led to an increase in multidrug-resistant infections. Hence, <em>S. aureus</em> presents a significant global health issue and its adaptations to the host environment are crucial for understanding pathogenesis and antibiotic susceptibility. When <em>S. aureus</em> is grown conventionally, its membrane lipids contain a mix of branched-chain and straight-chain saturated fatty acids. However, when unsaturated fatty acids are present in the growth medium, they become a major part of the total fatty acid composition. This study explores the biophysical effects of incorporating straight-chain unsaturated fatty acids into <em>S. aureus</em> membrane lipids. Membrane preparations from cultures supplemented with oleic acid showed more complex differential scanning calorimetry scans than those grown in tryptic soy broth alone. When grown in the presence of oleic acid, the cultures exhibited a transition significantly above the growth temperature, attributed to the presence of glycolipids with long-chain fatty acids causing acyl chain packing frustration within the bilayer. Functional aspects of the membrane were assessed by studying the kinetics of dye release from unilamellar vesicles induced by the antimicrobial peptide mastoparan X. Dye release was slower from liposomes prepared from cells grown in oleic acid-supplemented cultures, suggesting that changes in membrane lipid composition and biophysics protect the cell membrane against peptide-induced lysis. These findings underscore the intricate relationship between the growth environment, membrane lipid composition, and the physical properties of the bacterial membrane, which should be considered when developing new strategies against <em>S. aureus</em> infections.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 1","pages":"Article 184395"},"PeriodicalIF":2.8,"publicationDate":"2024-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142582032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Voltage- and Ca2+-inducible PLC activity for analyzing PI(4,5)P2 sensitivity of ion channels in Xenopus oocytes","authors":"Takafumi Kawai , Natsuki Mizutani , Yasushi Okamura","doi":"10.1016/j.bbamem.2024.184396","DOIUrl":"10.1016/j.bbamem.2024.184396","url":null,"abstract":"<div><div>Phosphatidylinositol 4,5-bisphosphate (PIP<sub>2</sub>) is a key membrane lipid regulating various ion channel activities. Currently, several molecular tools are used to modulate PIP<sub>2</sub> levels, each of which has distinct advantages and drawbacks. In this study, we proposed a novel methodology using heterologous <em>Xenopus</em> oocytes to precisely manipulate PIP<sub>2</sub> levels using phospholipase C (PLC)-ζ, which hydrolyzes PIP<sub>2</sub>. <em>Xenopus</em> oocytes injected with PLCζ exhibited notable hyperpolarization-induced Ca<sup>2+</sup> influx driven by the increased driving force of Ca<sup>2+</sup>. High Ca<sup>2+</sup> sensitivity of PLCζ facilitated hyperpolarization-induced PLC activity in <em>Xenopus</em> oocytes that was voltage- and Ca<sup>2+</sup>-dependent. This study demonstrated the regulatory capacity of PLCζ in modulating PIP<sub>2</sub>-sensitive ion channels, such as the KCNQ2/3 and GIRK channels, in a voltage- and Ca<sup>2+</sup>-dependent manner. Moreover, activation pathway of PLCζ only requires a two-electrode voltage clamp setup, making it a convenient molecular tool to manipulate PIP<sub>2</sub> levels in combination with a voltage-sensing phosphatase (VSP). PLCζ has distinct characteristics and advantages compared to VSP: (1) Hyperpolarization, but not depolarization, reduced the PIP<sub>2</sub> levels, (2) PIP<sub>2</sub> levels were decreased without any increase in phosphatidylinositol 4-monophosphate (PIP) levels, and (3) PIP<sub>2</sub> levels were reduced by Ca<sup>2+</sup> administration. Therefore, PLCζ effectively supports understanding how PIP<sub>2</sub> regulates ion channels, alongside VSP. Overall, this study highlights the unique characteristics of PLCζ and its distinct advantages in analyzing ion channel regulation by PIP<sub>2</sub> and the PLC pathway in <em>Xenopus</em> oocytes.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 1","pages":"Article 184396"},"PeriodicalIF":2.8,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142557053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Achismita Dutta , Brandon Burrell , Esha Prajapati , Sierra Cottle , Hailey Y. Maurer , Matthew J. Urban , Samuel R. Pennock , Arwa M. Muhamed , Janiyah Harris , Yesenia Flores , Lauren Staman , Benjamin R. Carone , Gregory A. Caputo , Timothy D. Vaden
{"title":"Lipid bilayer permeabilities and antibiotic effects of tetramethylguanidinium and choline fatty acid ionic liquids","authors":"Achismita Dutta , Brandon Burrell , Esha Prajapati , Sierra Cottle , Hailey Y. Maurer , Matthew J. Urban , Samuel R. Pennock , Arwa M. Muhamed , Janiyah Harris , Yesenia Flores , Lauren Staman , Benjamin R. Carone , Gregory A. Caputo , Timothy D. Vaden","doi":"10.1016/j.bbamem.2024.184393","DOIUrl":"10.1016/j.bbamem.2024.184393","url":null,"abstract":"<div><div>Ionic liquids (ILs) have been studied as potential components in antibiotic formulations based on their abilities to permeabilize and penetrate lipid bilayer, which correlate with their antibacterial effects. Fatty acid-based ILs (FAILs), in which the anion is a long-chain fatty acid, can permeabilize lipid membranes and have been used in biomedical applications since they have low human cell cytotoxicity. In this work we investigated the abilities of several different FAILs to permeabilize lipid bilayers and how that permeabilization correlates with antibacterial activity, cell membrane permeability, and cytotoxicity. The FAILs consisted of the cations tetramethylguanidinium (TMG) or choline combined with octanoate or decanoate. These FAILs were tested on model bilayer vesicles with three different lipid compositions for membrane permeabilization using a leakage assay. They were then tested for antibiotic and membrane permeabilization on bacterial and mammalian cells. The results show that while the octanoate-based FAILs do not form micelles and have low activities on vesicles and biological cells, the decanoate-based FAILs can permeabilize bilayers and have biological activities that correlate with the model vesicle results. The ILs with both cation and fatty-acid anion have strong activities while the decanoate alone has only minimal permeabilization and antibiotic activity. Membrane permeabilization occurs at FAIL concentrations below their CMC values which suggests that their mechanism of action may not involve micelle formation.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 1","pages":"Article 184393"},"PeriodicalIF":2.8,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142493945","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"TNF receptors: Structure-function relationships and therapeutic targeting strategies","authors":"Chih Hung Lo","doi":"10.1016/j.bbamem.2024.184394","DOIUrl":"10.1016/j.bbamem.2024.184394","url":null,"abstract":"<div><div>Tumor necrosis factor receptors (TNFR1 and TNFR2) play key roles in mediating inflammatory response and cell death signaling, which are associated with autoimmune disorders, neurodegenerative diseases, and cancers. The structure-function relationships of TNF receptors and their ligands determine the activation or inhibition of downstream signaling pathways. Available crystal structures have provided critical insights into the therapeutic targeting strategies of TNF receptors and their signaling networks. In this review, we discuss the potential of targeting receptor-ligand and receptor-receptor interactions in a competitive manner as well as perturbing receptor conformational dynamics through an allosteric mechanism to modulate TNF receptor signaling. We propose that conformational states of TNF receptors can act as a molecular switch in determining their functions and are important therapeutic targets. The knowledge of the structure-function relationships of TNF receptors can be applied to translational high-throughput drug screening and design of novel receptor-specific modulators with enhanced pharmacological properties.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 1","pages":"Article 184394"},"PeriodicalIF":2.8,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142493944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Conformational heterogeneity and structural features for function of the prototype viroporin influenza AM2","authors":"Kyriakos Georgiou, Antonios Kolocouris","doi":"10.1016/j.bbamem.2024.184387","DOIUrl":"10.1016/j.bbamem.2024.184387","url":null,"abstract":"<div><div>The 97-residue influenza A matrix 2 (ΑM2) protein, a prototype for viroporins, transports protons through water molecules and His37. We discuss structural biology and molecular biophysics experiments and some functional assays that have transformed over 40 years our understanding of the structure and function of AM2. The structural studies on ΑM2 have been performed with different conditions (pH, temperature, lipid, constructs) and using various protein constructs, e.g., AM2 transmembrane (AM2TM) domain, AM2 conductance domain (AM2CD), ectodomain-containing or ectodomain-truncated, AM2 full length (AM2FL) and aimed to describe the different conformations and structural details that are necessary for the stability and function of AM2. However, the conclusions from these experiments appeared sometimes ambiguous and caused exciting debates. This was not due to inaccurate measurements, but instead because of the different membrane mimetic environment used, e.g., detergent, micelles or phospholipid bilayer, the method (e.g., X-ray crystallography, solid state NMR, solution NMR, native mass spectrometry), the used protein construct (e.g., AM2TM or AM2CD), or the amino acids residues to follow observables (e.g., NMR chemical shifts). We present these results according to the different used biophysical methods, the research groups and often by keeping a chronological order for presenting the progress in the research. We discuss ideas for additional research on structural details of AM2 and how the present findings can be useful to explore new routes of influenza A inhibition. The AM2 research can provide inspiration to study other viroporins as drug targets.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 1","pages":"Article 184387"},"PeriodicalIF":2.8,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142457073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Benjamin J. Hardy, Holly C. Ford, May Rudin, J.L. Ross Anderson, Paul Curnow
{"title":"Polymer nanodiscs support the functional extraction of an artificial transmembrane cytochrome","authors":"Benjamin J. Hardy, Holly C. Ford, May Rudin, J.L. Ross Anderson, Paul Curnow","doi":"10.1016/j.bbamem.2024.184392","DOIUrl":"10.1016/j.bbamem.2024.184392","url":null,"abstract":"<div><div>Polymer nanodiscs are an attractive alternative to surfactants for studying integral membrane proteins within their native lipid environment. Here, we investigate the use of such polymers to isolate a computationally-designed <em>de novo</em> membrane cytochrome named CytbX. We show that the block copolymers known as CyclAPols can efficiently extract CytbX directly from biomembranes and are compatible with the downstream purification and biophysical characterisation of this artificial protein. CyclAPol-solubilised CytbX is well-folded and highly robust with properties that are essentially identical to those observed for the same protein in a detergent micelle. However, electron transfer to CytbX from a diffusive flavoprotein is substantially faster in micelles than in the nanodisc system. Our results confirm that polymer nanodiscs will be a useful tool for the ongoing study and application of <em>de novo</em> membrane proteins.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 1","pages":"Article 184392"},"PeriodicalIF":2.8,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142445970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Titas Mandal , Nadine Brandt , Carmelo Tempra , Matti Javanainen , Balázs Fábián , Salvatore Chiantia
{"title":"A comparison of lipid diffusive dynamics in monolayers and bilayers in the context of interleaflet coupling","authors":"Titas Mandal , Nadine Brandt , Carmelo Tempra , Matti Javanainen , Balázs Fábián , Salvatore Chiantia","doi":"10.1016/j.bbamem.2024.184388","DOIUrl":"10.1016/j.bbamem.2024.184388","url":null,"abstract":"<div><div>Cellular membranes are composed of lipids typically organized in a double-leaflet structure. Interactions between these two leaflets – often referred to as interleaflet coupling – play a crucial role in various cellular processes. Despite extensive study, the mechanisms governing such interactions remain incompletely understood. Here, we investigate the effects of interleaflet coupling from a specific point of view, i.e. by comparing diffusive dynamics in bilayers and monolayers, focusing on potential lipid-specific interactions between opposing leaflets. Through quantitative fluorescence microscopy techniques, we characterize lipid diffusion and mean molecular area in monolayers and bilayers composed of different lipids. Our results suggest that the observed decrease in bilayer lipid diffusion compared to monolayers depends on lipid identity. Furthermore, our analysis suggests that lipid acyl chain structure and spatial configuration at the bilayer may strongly influence interleaflet interactions and dynamics in bilayers. These findings provide insights into the role of lipid structure in mediating interleaflet coupling and underscore the need for further experimental investigations to elucidate the underlying mechanisms.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 1","pages":"Article 184388"},"PeriodicalIF":2.8,"publicationDate":"2024-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142457072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}