Biochimica et biophysica acta. Biomembranes最新文献

{"title":"Conformational heterogeneity and structural features for function of the prototype viroporin influenza AM2","authors":"Kyriakos Georgiou,&nbsp;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}

{"title":"Polymer nanodiscs support the functional extraction of an artificial transmembrane cytochrome","authors":"Benjamin J. Hardy,&nbsp;Holly C. Ford,&nbsp;May Rudin,&nbsp;J.L. Ross Anderson,&nbsp;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}

{"title":"A comparison of lipid diffusive dynamics in monolayers and bilayers in the context of interleaflet coupling","authors":"Titas Mandal ,&nbsp;Nadine Brandt ,&nbsp;Carmelo Tempra ,&nbsp;Matti Javanainen ,&nbsp;Balázs Fábián ,&nbsp;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}

{"title":"Evidence for phospholipid self-organisation in concentrated ammonia-water environments","authors":"Sean M. Mackay ,&nbsp;Ben Sutherland ,&nbsp;Richard A. Easingwood ,&nbsp;Andrew Hopkins ,&nbsp;Mihnea Bostina ,&nbsp;Eng Wui Tan","doi":"10.1016/j.bbamem.2024.184391","DOIUrl":"10.1016/j.bbamem.2024.184391","url":null,"abstract":"<div><div>Titan, the largest moon of Saturn is thought to have the potential to support primordial life. The surface of Titan contains bodies of liquid hydrocarbons, and modelling suggests that an ammonia-water ocean resides deep beneath the surface, both of which have been speculated to support primordial chemistry. Here we present the first evidence that both preformed and self-organised phospholipid vesicles remain stable and can maintain concentration gradients in ammonia-water environments; a fundamental requirement for primordial chemistry and biology to originate. We further reveal the remarkable stability of a diether phospholipid, such as those found in extremophilic bacteria, under these conditions and demonstrate that electron microscopy and tomography are useful tools to investigate macromolecular structure under diverse physico-chemical environments.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1866 8","pages":"Article 184391"},"PeriodicalIF":2.8,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142399174","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":"Nanodisc-associated acetylcholinesterase as a novel model system of physiological relevant membrane-bound cholinesterases. Inhibition by phenolic compounds","authors":"Paula Belén Salazar ,&nbsp;Fernando Gabriel Dupuy ,&nbsp;Mariana C. Fiori ,&nbsp;Samantha M. Stanfield ,&nbsp;Jon McCord ,&nbsp;Guillermo A. Altenberg ,&nbsp;Carlos Javier Minahk","doi":"10.1016/j.bbamem.2024.184389","DOIUrl":"10.1016/j.bbamem.2024.184389","url":null,"abstract":"<div><div>Acetylcholinesterase (AChE) plays a pivotal role in the cholinergic system, and its inhibition is sought after in a wide range of applications, from insect control to Alzheimer's disease treatment. While the primary physiological isoforms of AChE are membrane-bound proteins, most assays for discovering new, safer, and potent inhibitors are conducted using commercially available soluble isoforms, such as the electric eel AChE (eeAChE). In this study, we conducted a comparative analysis of the activity and selectivity to phenolic inhibitors of recombinant human AChE, eeAChE and a mutant variant of human AChE known as dAChE4. Despite numerous mutations, dAChE4 closely resembles its parental protein and serves as a suitable model for monomeric human AChE. We also established an in vitro system of membrane-bound AChE to create a model that closely mimics the physiological isoforms. This system ensures the proper work of the enzyme and allowed us to control the exact concentration of enzyme and lipids per assay.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1866 8","pages":"Article 184389"},"PeriodicalIF":2.8,"publicationDate":"2024-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142387602","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":"The dimer of human SVCT1 is key for transport function","authors":"Menebere Woubshete ,&nbsp;Lok I. Chan ,&nbsp;George Diallinas ,&nbsp;Bernadette Byrne","doi":"10.1016/j.bbamem.2024.184390","DOIUrl":"10.1016/j.bbamem.2024.184390","url":null,"abstract":"<div><div>Humans and other primates lack the ability to synthesize the essential nutrient, Vitamin C, which is derived exclusively from the diet. Crucial for effective vitamin C uptake are the Na⁺ dependent Vitamin C transporters, SVCT1 and SVCT2, members of the nucleobase ascorbate transporter (NAT) family. SVCT1 and 2 actively transport the reduced form of Vitamin C, ascorbic acid, into key tissues. The recent structure of the mouse SVCT1 revealed the molecular basis of substrate binding and that, like the other structurally characterised members of the NAT family, it exists as a closely associated dimer. SVCT1 is likely to function via the elevator mechanism with the core domain of each protomer able to bind substrate and move through the membrane carrying the substrate across the membrane. Here we explored the function of a range of variants of the human SVCT1, revealing a range of residues involved in substrate selection and binding, and confirming the importance of the C-terminus in membrane localisation. Furthermore, using a dominant negative mutant we show that the dimer is essential for transport function, as previously seen in the fungal homologue, UapA. In addition, we show that a localisation deficient C-terminal truncation of SVCT1 blocks correct localisation of co-expressed, associated wildtype SVCT1. These results clearly show the importance of the dimer in both correct SVCT1 trafficking and transport activity.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1866 8","pages":"Article 184390"},"PeriodicalIF":2.8,"publicationDate":"2024-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142380031","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":"A molecular mechanism for how pressure induces interdigitation of phospholipid bilayer membranes","authors":"Masaki Goto ,&nbsp;Shuntaro Yoshida ,&nbsp;Shigeyuki Habara ,&nbsp;Agnieszka Wilk-Kohlbrecher ,&nbsp;Joachim Kohlbrecher ,&nbsp;Nobutake Tamai ,&nbsp;Hitoshi Matsuki","doi":"10.1016/j.bbamem.2024.184385","DOIUrl":"10.1016/j.bbamem.2024.184385","url":null,"abstract":"<div><div>The phase transition from the ripple gel phase to the interdigitated gel phase of bilayers of phosphatidylcholines (PCs) with two saturated long-chain fatty acids under high pressure was investigated by pressure-scanning microscopy, fluorometry, and dynamic light scattering (DLS) measurements. Microscopic observation for giant vesicles (GVs) of distearoyl-PC (DSPC) under high pressure showed that spherical GVs transforms significantly into warped and distorted spherical ones instantaneously at the pressure-induced interdigitation. The fluorescence intensities of amphiphilic probe Prodan and hydrophobic probe Laurdan in the dipalmitoyl-PC (DPPC) bilayer steeply decreased and increased, respectively, at the interdigitation, suggesting that the conformational change of the polar head group of DPPC molecule in the bilayer transiently occurred at the interdigitation. Further, it was found from the high-pressure DLS measurements that the size of the vesicle particles of the DPPC and DSPC transiently increases near the interdigitation pressure, whereas the chemically induced interdigitation by adding ethanol to the DSPC bilayer membrane under atmospheric pressure produce no such change in the particle size. Taking account of the critical packing parameter of the PC molecule, the above experimental results would lead us to the conclusion that the pressure-induced interdigitation is attributable to the increase in repulsive interaction between the polar head groups of the PC molecules resulting from the orientational change of the head group from a parallel alignment to a perpendicular one with respect to the bilayer surface by applying pressure, namely the transient state: it occurs when the repulsive interaction exceeds a threshold value for the balance between the repulsive interaction and the attractive interaction among the hydrophobic acyl chains.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1866 8","pages":"Article 184385"},"PeriodicalIF":2.8,"publicationDate":"2024-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142340432","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":"Alamethicin channel inactivation caused by voltage-driven flux of alamethicin","authors":"Joshua J. Maraj,&nbsp;Jessie D. Ringley,&nbsp;Stephen A. Sarles","doi":"10.1016/j.bbamem.2024.184386","DOIUrl":"10.1016/j.bbamem.2024.184386","url":null,"abstract":"<div><div>We show that voltage alone can inactivate alamethicin channels, which has been previously observed for monazomycin and suzukacillin channels. The voltage required to trigger inactivation is above the potential to form channels, and, like with channel activation, this threshold reduces with increasing peptide concentration and membrane fluidity. Since similar monazomycin channels inactivate via channel break up and translocation, we hypothesized that inactivation of alamethicin channels occurs via the same mechanism. Our data prove this hypothesis to be true through two experiments. First, we show that inactivation of channels at positive voltages when peptides are supplied to only the <em>cis</em> side correlates to new channel activity on the <em>trans</em> side at negative potentials. This result indicates translocation of alamethicin peptides occurs only during voltage-induced inactivation. Second, we measured the ratio of steady-state (with inactivation) to ideal (without inactivation) conductance versus voltage for membranes with equal amounts of alamethicin on both sides and used these values to quantify alamethicin flux. Plotting flux versus steady-state conductance across multiple alamethicin concentrations shows a single linear dependence, signifying that translocated peptides originate from active channels that break up under prolonged voltage. Given the frequent use of alamethicin as model ion channels, these results add important understanding of their kinetic responses when subjected to prolonged, high voltages.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1866 8","pages":"Article 184386"},"PeriodicalIF":2.8,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142340433","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":"Benzohydroxamate and nitrobenzohydroxamate affect membrane order: Correlations between spectroscopic and molecular dynamics to approach tuberculosis","authors":"Lucas Thadeu Felipe Kokuszi ,&nbsp;Yago Mendes Paes ,&nbsp;Aline Loise Santana Faria ,&nbsp;Jesus Alvarado-Huayhuaz ,&nbsp;Maurício Dornelles Caldeira Balboni ,&nbsp;Marinalva Cardoso dos Santos ,&nbsp;Sandra Cruz dos Santos ,&nbsp;Juliano Rosa de Menezes Vicenti ,&nbsp;Alexandre Luis Parize ,&nbsp;Adriano Velasque Werhli ,&nbsp;Karina dos Santos Machado ,&nbsp;Vânia Rodrigues de Lima","doi":"10.1016/j.bbamem.2024.184378","DOIUrl":"10.1016/j.bbamem.2024.184378","url":null,"abstract":"<div><p>This work correlates the effects of benzohydroxamate (BH) and nitrobenzohydroxamate (NBH) anions in two membrane models which may be used for anti-tuberculosis (anti-TB) spectroscopic studies and/or computational studies. Firstly, the BH and NBH influence in the physico-chemical properties of soy asolectin (ASO)-based large multilamellar vesicles (MLVs) were evaluated by spectroscopic and calorimetric studies. In parallel, the BH and NBH interaction with a <em>Mycobacterium tuberculosis</em> (Mtb) inner membrane model, composed of phosphatidyl-myo-inositol-dimannoside (PIM₂), was investigated by molecular dynamics (MD) simulations. Spectroscopic data showed a localization of BH close to the lipid phosphate group, while NBH was found close to the choline region. The BH ordered the ASO choline, phosphate and carbonyl regions and disrupted the acyl methylenes, reducing the membrane packing of the lipid hydrophobic region. On the other hand, NBH showed an ordering effect in all the lipid groups (polar, interface and hydrophobic ones). By MD studies, it was found that NBH enhanced the stability of the PIM₂ membrane more than BH, while also being positioned closer to its mannosyl oxygens. As in ASO MLVs, BH was localized close to the PIM₂ phosphate group and disrupted its acyl chains. However, higher values of lateral diffusion were observed for NBH than BH. Despite this, BH and NBH increased the membrane thickness by 35 %, which suggests a global ordering effect of both drugs. Findings of this work reinforce the accordance and complementarity between MLVs based on ASO and the PIM₂ MD model results to study the drug effects in Mtb membrane properties.</p></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1866 8","pages":"Article 184378"},"PeriodicalIF":2.8,"publicationDate":"2024-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142008217","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":"Foam fractionation studies of recombinant human apolipoprotein A-I","authors":"Kyle Lethcoe ,&nbsp;Colin A. Fox ,&nbsp;Anouar Hafiane ,&nbsp;Robert S. Kiss ,&nbsp;Jianfang Liu ,&nbsp;Gang Ren ,&nbsp;Robert O. Ryan","doi":"10.1016/j.bbamem.2024.184375","DOIUrl":"10.1016/j.bbamem.2024.184375","url":null,"abstract":"<div><p>Apolipoprotein A-I (apoA-I), the primary protein component of plasma high-density lipoproteins (HDL), is comprised of two structural regions, an N-terminal amphipathic α-helix bundle domain (residues 1–184) and a hydrophobic C-terminal domain (residues 185–243). When a recombinant fusion protein construct [bacterial pelB leader sequence – human apoA-I (1–243)] was expressed in <em>Escherichia coli</em> shaker flask cultures, apoA-I was recovered in the cell lysate. By contrast, when the C-terminal domain was deleted from the construct, large amounts of the truncated protein, apoA-I (1–184), were recovered in the culture medium. Consequently, following pelB leader sequence cleavage in the <em>E. coli</em> periplasmic space, apoA-I (1–184) was secreted from the bacteria. When the pelB-apoA-I (1–184) fusion construct was expressed in a 5 L bioreactor, substantial foam production (~30 L) occurred. Upon foam collection and collapse into a liquid foamate, SDS-PAGE revealed that apoA-I (1–184) was the sole major protein present. Incubation of apoA-I (1–184) with phospholipid vesicles yielded reconstituted HDL (rHDL) particles that were similar in size and cholesterol efflux capacity to those generated with full-length apoA-I. Mass spectrometry analysis confirmed that pelB leader sequence cleavage occurred and that foam fractionation did not result in unwanted protein modifications. The facile nature and scalability of bioreactor-based apolipoprotein foam fractionation provide a novel means to generate a versatile rHDL scaffold protein.</p></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1866 7","pages":"Article 184375"},"PeriodicalIF":2.8,"publicationDate":"2024-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141916050","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}