Biochimica et biophysica acta. Biomembranes最新文献

{"title":"Investigation of biophysical properties of ion channels with nonlinear methods","authors":"Mahmut Akilli ,&nbsp;Fatma Söğüt ,&nbsp;Ülkü Çömelekoğlu ,&nbsp;Handan Tuncel","doi":"10.1016/j.bbamem.2025.184437","DOIUrl":"10.1016/j.bbamem.2025.184437","url":null,"abstract":"<div><div>The aim of this study is to show how nonlinear methods can be used to investigate the biophysical properties of ion channels. For this purpose, the membrane ion current signals of the EAG1 potassium channel of MCF-7 cells and of the TRP channel of ARPE-19 cells were used. Entropy measurements and maximum Lyapunov exponent were chosen as nonlinear methods. The vital state functional of the ion channels in the membrane was monitored using the entropy parameter. The behavioural or functional sensitivity of ion channels was quantified by the maximum Lyapunov exponent. It is known that the entropy of a system increases as it moves towards equilibrium. In this context, during the electrical activity of a living cell, the entropy of the cell reaches its maximum when the membrane ion fluxes reach the equilibrium, that is, when the value of the ion fluxes approaches zero. Therefore, the accuracy of the results obtained in this study was calibrated by reference to this general assumption. The results show functional differences between the MCF-7 EAG1 potassium channel and the ARPE-19 TRP channel. This method has potential applications in analysing cell behaviour or studying ion channel biophysical properties. It can also be used to observe differences in the behaviour of normal and cancerous cells of the same type, or to measure the effects of drugs on the cell.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 7","pages":"Article 184437"},"PeriodicalIF":2.5,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144757922","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":"Accurate antibiotic accumulation in Enterobacteriaceae isolates expressing efflux pumps","authors":"Jinane Tabcheh ,&nbsp;Julia Vergalli ,&nbsp;Jean-Marie Pagès ,&nbsp;Jean Michel Brunel","doi":"10.1016/j.bbamem.2025.184441","DOIUrl":"10.1016/j.bbamem.2025.184441","url":null,"abstract":"<div><div>In <em>Enterobacteriaceae</em>, antibiotic susceptibility is frequently influenced by mechanisms such as membrane modifications, target site mutations, and enzymatic resistance barriers. Recently, there has been a notable rise in <em>Klebsiella pneumoniae</em>, <em>Escherichia coli</em>, and <em>Enterobacter cloacae</em> isolates exhibiting antibiotic resistance in hospital settings. Of particular concern, some resistant isolates employ membrane-associated resistance mechanisms that significantly lower intracellular antibiotic concentrations, reducing them below the threshold required for therapeutic efficacy. Advancements in methods for quantifying drug accumulation within bacterial cells have provided critical insights into these resistance mechanisms. A key step in these studies relies on cell lysis to release intracellular contents including antibacterial molecules for precise quantification. However, current lysis methods are often time-consuming, underscoring the need for a robust, efficient approach to accurately measure intracellular antibiotic concentrations in isolates exhibiting various levels of efflux pump activity. In this study, we developed a rapid and reliable lysis protocol that minimizes the risk of drug alteration while enabling precise and reproducible measurement of intracellular antibiotic concentrations allowing an evidence-based study of efflux in resistant clinical strains of <em>Enterobacteriaceae</em>. This approach holds significant promise for enhancing our understanding of membrane-associated resistance mechanisms and for informing the optimization of treatment strategies.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 7","pages":"Article 184441"},"PeriodicalIF":2.5,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144809825","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":"Effect of membrane tension on (−)-epigallocatechin gallate-induced burst of single giant unilamellar vesicles","authors":"Yukihiro Tamba ,&nbsp;Naoya Sugita ,&nbsp;Mika Terada ,&nbsp;Masahito Yamazaki","doi":"10.1016/j.bbamem.2025.184427","DOIUrl":"10.1016/j.bbamem.2025.184427","url":null,"abstract":"<div><div>(−)-Epigallocatechin gallate (EGCg), a tea catechin, exhibits antimicrobial activity. EGCg induces burst of giant unilamellar vesicles (GUVs), resulting in leakage of their internal contents. Here, we examined the effect of membrane tension on the EGCg-induced burst of dioleoylphosphatidylcholine (DOPC)-GUVs. The observation of the EGCg-induced burst of GUVs without membrane tension indicated that first a micropore was formed in the membrane and then its radius rapidly increased with time within ~10 ms without a change in the GUV diameter, and then the GUV diameter decreased to a lipid membrane aggregate. Next, we examined the effect of membrane tension on the EGCg-induced fractional area change (<em>δ</em>) of GUVs and its burst. During the interaction of EGCg with a GUV with low tension (≤ 0.5 mN/m), the <em>δ</em> initially increased slightly and then decreased to negative values, concomitant with the appearance of invaginated structures such as dense particles and narrow tubes in the GUV membrane and lumen, resulting in pore formation and subsequent GUV burst. By contrast, at higher tension, <em>δ</em> increased with time. The fraction of burst GUV after 5 min of interaction, <em>P</em>_burst (5 min), decreased with increasing tension up to 3.0 mN/m, indicating that membrane tension suppressed the burst. The <em>P</em>_burst (5 min) increased with increasing the fraction of GUVs in which invaginated structures appeared within 5 min of interaction, suggesting that the formation of invaginated structures may cause the initial EGCg-induced pore formation. We have proposed a mechanism of the tension effect on the EGCg-induced pore formation.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 5","pages":"Article 184427"},"PeriodicalIF":2.8,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144172125","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":"Acidic bicelles are a suitable membrane mimic for structural studies of the Lassa virus fusion domain","authors":"Hallie N. Pennington,&nbsp;Jinwoo Lee","doi":"10.1016/j.bbamem.2025.184428","DOIUrl":"10.1016/j.bbamem.2025.184428","url":null,"abstract":"<div><div>Lassa virus (LASV) is the most prevalent arenavirus afflicting humans and has high pandemic potential. The genetic material of LASV is delivered into the host cell via membrane fusion initiated by the LASV fusion domain (FD). However, the molecular details of the LASV FD, particularly its structure after association with the host cell, remain poorly characterized. This can be attributed to a lack of a viable membrane mimic to effectively stabilize the LASV FD for structural studies. Here, we demonstrate that the structure of the LASV FD widely varies based on the class of membrane mimic. In particular, through CD spectroscopy, we found that the LASV FD required a charged membrane mimic, such as zwitterionic or anionic detergent micelles, to adopt a helical conformation at low pH, but has the highest helical content in the presence of anionic lipids, particularly the detergent micelle LMPG and acidic bicelles. Moreover, we reveal that the LASV FD was well resolved on NMR spectra in CHAPS, DPC, LDAO, LMPG, and acidic bicelles, where LMPG and acidic bicelles had the sharpest peak resolution, but more defined peaks were noted in acidic bicelles over LMPG. In conclusion, our findings indicate that acidic bicelles are the optimal membrane mimic for the stabilization of the LASV FD such that structural studies can be conducted.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 5","pages":"Article 184428"},"PeriodicalIF":2.8,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144231702","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":"Influence of lipid saturation on the structural properties of styrene maleic acid lipid nanoparticles (SMALPs)","authors":"Evelyn A. Okorafor ,&nbsp;Emma A. Gordon ,&nbsp;Indra D. Sahu ,&nbsp;Muhammad Zeeshan Shah ,&nbsp;Dominik Konkolewicz ,&nbsp;Gary A. Lorigan","doi":"10.1016/j.bbamem.2025.184424","DOIUrl":"10.1016/j.bbamem.2025.184424","url":null,"abstract":"<div><div>Membrane bilayers are complex three-dimensional structures whose molecular events in the deep dimensions of membrane lipids are crucial for understanding membrane function. This study investigates the interaction of coexisting membrane domains in terms of hydrophobicity, alkyl chain order, and fluidity using Styrene Maleic Acid (SMA) copolymers as membrane mimics. We employed continuous wave electron paramagnetic resonance spectroscopy (CW-EPR) to characterize the structural dynamic properties of membrane domains without separation. Lipid-spin probe vesicles were prepared using phospholipids with varying degrees of saturation (DOPC, POPC, DMPC, and DSPC) and doxyl spin-labeled phospholipids at different depths (5, 12, and 16-doxyl PC) as membrane probes. These vesicles were titrated with two SMA polymers of different hydrophobic tail lengths. Dynamic light scattering (DLS) confirmed the formation of Styrene Maleic Acid lipid nanoparticles (SMALPs). CW-EPR spectroscopy was used to characterize the dynamic properties of vesicles incorporated into the SMALP systems. Analysis of the CW-EPR spectral line shape data revealed that the hydrophobic tail of SMA, the degree of lipid saturation, and the length of phospholipids significantly affect membrane fluidity and alkyl chain ordering, as well as lipid interactions. Notably, samples containing DSPC, a fully saturated longer-chain phospholipid, and those containing SMA exhibited increased rigidity of motion, reduced fluidity, and improved ordering of the alkyl chain in the membrane. This study provides crucial insights into the molecular dynamics of membrane bilayers and the impact of SMA copolymers on membrane properties, contributing to our understanding of fundamental membrane functions such as lateral movement of proteins and lipids.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 5","pages":"Article 184424"},"PeriodicalIF":2.8,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144141407","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":"Effect of glucosylation for the vertical movement of cholesterol in bilayer membranes","authors":"Shinya Hanashima ,&nbsp;Takafumi Asahina ,&nbsp;Raymond Malabed ,&nbsp;Katsuaki Sasaki ,&nbsp;Michio Murata","doi":"10.1016/j.bbamem.2025.184422","DOIUrl":"10.1016/j.bbamem.2025.184422","url":null,"abstract":"<div><div>Cholesterol (Chol) in mammalian cell membranes facilitates the assembly of dynamic membrane domains that are involved in vital biological processes through lateral and transbilayer movements in the membranes. In the cell membranes, Chol undergoes glucose transglycosylation to produce cholesteryl-β-<span>d</span>-glucoside (ChoGlc). ChoGlc is involved in neurodegenerative diseases and accumulates in lysosomal storage disorders. However, the effects of glucosylation on membrane properties of Chol remain unclear. We investigated the membrane interaction of ChoGlc and its subsequent translocation between leaflets using fluorescent probes, such as 4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) and the newly synthesized 7-nitro-2,1,3-benzoxadiazole-labeled ChoGlc (NBD-ChoGlc) in dioleoylphosphatidylcholine (DOPC) membranes. The fluorescence of TMA-DPH, which selectively reported the order of the outer leaflet of the bilayer, indicated that ChoGlc added to the external solution, was mostly incorporated into the membranes and increased the DOPC membrane ordering. Furthermore, the anisotropy values reached a level similar to that of the ChoGlc-preloaded symmetric vesicle within approximately 5 min owing to the rapid distribution of ChoGlc in both leaflets. This was further confirmed by the selective fluorescence quenching of NBD-ChoGlc in the outer leaflet through irreversible quenching by dithionite. The similarity of the fluorescence decay curves of NBD-ChoGlc and NBD-Chol indicated that the glucosylation had little impact on the flip-flops of Chol in the DOPC bilayers. Our data demonstrates that some of the important membrane properties of Chol, such as fast flip-flop between leaflets and increased membrane order, were mostly maintained in ChoGlc despite hydrophilic glucose modification.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 5","pages":"Article 184422"},"PeriodicalIF":2.8,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143918419","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":"Interactions of hinokitiol with fungal membrane lipids in model systems","authors":"Beata Wyżga ,&nbsp;Magdalena Skóra ,&nbsp;Karolina Olechowska ,&nbsp;Katarzyna Hąc-Wydro","doi":"10.1016/j.bbamem.2025.184423","DOIUrl":"10.1016/j.bbamem.2025.184423","url":null,"abstract":"<div><div>Hinokitiol (β-thujaplicin) is a naturally occurring substance of antimicrobial properties, which can be used e.g. as a cosmetic preservative. In this work the influence of hinokitiol on the monolayers and bilayers formed from fungal membrane lipids (1-palmitoyl-2-oleoyl-<em>sn</em>-glycero-3-phosphoethanolamine – POPE; 1-palmitoyl-2-oleoyl-<em>sn</em>-glycero-3-phosphocholine – POPC and ergosterol) was investigated. These studies aimed to investigate the effect of hinokitiol on fungal membranes, being indicated as a target for this compound. In this context, the affinity of hinokitiol for ergosterol-containing membranes was of particular interest. The in vitro antifungal activity of hinokitiol was also determined. The results showed that hinokitiol is active against the <em>Candida</em> species tested and exhibits stronger antifungal than antibacterial activity. Moreover, hinokitiol alters the properties of model membranes and the observed effects correlated with ergosterol content in the system. Namely, the higher the ergosterol content, the greater the fluidizing and destabilising effect of hinokitiol and its removal from the model. Moreover, hinokitiol is not able to penetrate into ergosterol membranes; instead, causes strong destabilization of the film and dragging the monolayer material into the subphase. Thus, hinokitiol changes properties of model membrane by the exclusion of the molecules from the interface. The results evidenced differences in the interactions of hinokitiol with ergosterol vs phospholipids, and the interactions of hinokitiol with the membrane depend on the presence and levels of ergosterol. Thus, ergosterol can be a molecular target for this compound. Moreover, the presence of ergosterol in fungal membranes and its lack in bacteria membranes may explain stronger antifungal vs antibacterial effect of hinokitiol.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 5","pages":"Article 184423"},"PeriodicalIF":2.8,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143916398","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":"An advanced spectroscopic and crystallographic study on a synergistic composition of a 1,3,4-thiadiazole derivative and amphotericin B, in model biological liposomal system","authors":"Lidia Ślusarczyk ,&nbsp;Klaudia Rząd ,&nbsp;Daniel Kamiński ,&nbsp;Mariusz Gagoś ,&nbsp;Małgorzata Figiel ,&nbsp;Arkadiusz Matwijczuk","doi":"10.1016/j.bbamem.2025.184432","DOIUrl":"10.1016/j.bbamem.2025.184432","url":null,"abstract":"<div><div>The paper presents the results of the first spectroscopic, microcalorimetric, and crystallographic study analyzing in great detail the strongly synergistic composition containing a selected <em>1,3,4</em>-thiadiazole derivative: <em>4-</em>(<em>5-methyl-1,3,4-thiadiazol-2-ylo</em>)<em>benzene-1,3-diol</em> (<strong>C1</strong>) and the antibiotic amphotericin B (<strong>AmB</strong>) in model biological DPPC films additionally modified with sterols: cholesterol (<strong>Chol</strong>) and ergosterol (<strong>Erg</strong>). The spectroscopic properties of the analyzed composition were studied with the use of spectroscopic methods, including: measurements of electronic fluorescence and absorption spectra with the technique of resonance light scattering (RLS), measurements of stationary fluorescence anisotropy and time-resolved fluorescence lifetimes with the method of single photon counting (TCSPC), circular dichroism spectra (CD), and infrared FTIR spectra. The mentioned methods were further complemented by including microcalorimetric DSC and crystallographic XRD analyses. All the measurements were taken in model biological systems formed as liposomal films and liposomal multilayers composed of DPPC and/or modified with sterols: cholesterol and ergosterol. The absorption spectra measured for C1/AmB and the synergistic composition thereof revealed differences indicating that while the antibiotic forms retained its known tendency to form aggregate in film systems, the synergistic composition had certain effects on the aggregational equilibrium. This was also reflected in the fluorescence emission measured for said systems, in particular the RLS and CD spectra, as well as, to an extent, the results of fluorescence anisotropy measurements. As we proceeded to the analysis of FTIR spectra, it was observed that the synergistic composition of C1 + AmB showed stronger interaction with the hydrophobic layer of the film. In turn, the crystallographic measurements performed for the synergistic composition revealed its impact on the multilayer's thickness. Finally, microcalorimetric measurements indicated that the synergistic composition had a lesser impact on the main phase transition temperature of the lipid, as compared to the respective compounds tested separately. The presented paper is the most detailed report to date pertaining to the synergism observed for the relevant systems analyzed in model biological films modified with sterols.</div><div>The study provides an in-depth spectroscopic, microcalorimetric, and crystallographic description of the molecular interactions analyzed for said molecular systems in model films formed of DPPC with the addition of sterols. Its results are particularly significant given the fact that AmB continues to be a clinically relevant antibiotic employed in the treatment of particularly severe internal mycoses and against otherwise resistant fungal strains.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 5","pages":"Article 184432"},"PeriodicalIF":2.8,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144534809","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":"Amino acids critical for lipid/s-interaction at the lipid-water-interface of TRPV5/TRPV6 remain different during vertebrate radiation: Relevance in cancer, bone disorders and other pathophysiologies","authors":"Sweta Agarwal ,&nbsp;Vikash Kumar ,&nbsp;Anupriya Chattapadhya ,&nbsp;Shamit Kumar ,&nbsp;Luna Goswami ,&nbsp;Chandan Goswami","doi":"10.1016/j.bbamem.2025.184433","DOIUrl":"10.1016/j.bbamem.2025.184433","url":null,"abstract":"<div><div>TRPV5 and TRPV6 are members of the TRP superfamily of ion channels and are present in almost all vertebrates as linked-genes with high homology and functional similarities. Abnormalities in the regulation or function of these two channels cause multiple pathological conditions, making these highly relevant for several diseases and pharmacological applications. In this context, how these two channels differ from each other is largely unknown. Here we analysed ∼250 protein sequences from vertebrates and critically analysed the conservation of signature motifs, such as different domains, TM-regions, loop-regions, cholesterol-binding regions and lipid-water-interface (LWI) regions. We demonstrate the subtle differences in the motifs and residues that are present at the LWI in TRPV5 and TRPV6. The ratio of hydrophobic-to-hydrophilic residues (but not of positive-to-negative residues) remains conserved for TRPV5 and TRPV6 throughout the vertebrate evolution. We also found motifs where cholesterol and/or sphingolipid can interact with TRPV5 and TRPV6 yet with different energies, both in open- and close-conformation. Accordingly, experimental evidence suggest that partial depletion of membrane cholesterol lowers the agonist-mediated opening of TRPV6, confirming the importance of membrane cholesterol for channel function. Further analysis of somatic mutations suggests that the specific inner LWI regions of TRPV5 (first 3) and TRPV6 (first 5) impose mutational hot-spots that are linked with different cancers. These findings may have broad significance in designing pharmacological agents for targeting TRPV5 and TRPV6 separately or simultaneously.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 5","pages":"Article 184433"},"PeriodicalIF":2.8,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144551838","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":"Evaluation of aquaporin Z water permeability in bilayers using droplet interface systems with internal-pressure–defined membrane tension","authors":"Misuzu Ueki ,&nbsp;Takahisa Maki ,&nbsp;Masayuki Iwamoto","doi":"10.1016/j.bbamem.2025.184425","DOIUrl":"10.1016/j.bbamem.2025.184425","url":null,"abstract":"<div><div>Cell membranes regulate water flow to maintain homeostasis, cell volume, and osmotic balance. Aquaporins (AQPs) enable selective water transport, making precise permeability measurements essential for understanding their function. The current methods have limitations, including high resource demands and poor control over membrane properties like bilayer tension. In this study, the droplet interface bilayer (DIB) system was used to measure aquaporin water channel activity. Unlike conventional water permeability assays, this method uniquely quantifies lipid bilayer tension by determining droplet internal pressure. This pressure-determined DIB (PDIB) method was used to investigate the water permeability of a lipid bilayer reconstituted with <em>Escherichia coli</em> aquaporin Z (AqpZ). Water permeability increased in an AqpZ concentration-dependent manner at bilayer tensions of 2.2–3.0 mN/m and was inhibited by mercury (IC₅₀, 340 μM). Fluorescence microscopy was performed to visualize and quantify AqpZ molecules, thereby allowing us to derive an approximate estimate of the unitary water permeability. Although this study established the PDIB method and demonstrated its applicability to AqpZ, this technique may also facilitate future investigations on the effects of lipid bilayer tension on aquaporin function and the fundamental mechanisms of water transport across biological membranes.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 5","pages":"Article 184425"},"PeriodicalIF":2.8,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144115070","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}