Biochimica et biophysica acta. Biomembranes最新文献

{"title":"Lipopolysaccharide supramolecular organization regulates the activation of coagulation factor XII","authors":"André L. Lira ,&nbsp;Ting Liu ,&nbsp;Joseph E. Aslan ,&nbsp;Cristina Puy ,&nbsp;Owen J.T. McCarty","doi":"10.1016/j.bbamem.2025.184415","DOIUrl":"10.1016/j.bbamem.2025.184415","url":null,"abstract":"<div><div>Lipopolysaccharides (LPS) are key bacterial membrane components that activate coagulation factor XII (FXII), establishing a critical link between bacterial infections, blood coagulation, and inflammation. This study investigates how the supramolecular organization of LPS—monomers, micelles, and bilayers—affects FXII activation. We demonstrate that LPS micelles uniquely activate FXII to its enzymatic form (FXIIa), while monomeric LPS modulates FXIIa activity without direct activation, and bilayer-form LPS does not induce FXII activation. The addition of calcium ions (Ca²⁺) promoted the formation of bilayers by binding to the negatively charged phosphate groups of LPS, reducing electrostatic repulsion and stabilizing LPS aggregates, potentially leading to a shift in their net charge. These findings highlight the pivotal role of LPS supramolecular structure in modulating FXII activity, providing mechanistic insights into the interplay between bacterial components and the coagulation cascade.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 3","pages":"Article 184415"},"PeriodicalIF":2.8,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143349958","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":"Lock and key: Quest to find the most compatible membrane mimetic for studying membrane proteins in native environment","authors":"Rahul Yadav ,&nbsp;Debarghya Pratim Gupta ,&nbsp;Chandan Singh","doi":"10.1016/j.bbamem.2025.184414","DOIUrl":"10.1016/j.bbamem.2025.184414","url":null,"abstract":"<div><div>Membrane proteins play crucial roles in cellular signal transduction, molecule transport, host-pathogen interactions, and metabolic processes. However, mutations, changes in membrane properties, and environmental factors can lead to loss of protein function. This results in impaired ligand binding and misfolded structures that prevent proteins from adopting their native conformation. Many membrane proteins are also therapeutic targets in various diseases, where drugs can either restore or inhibit their specific functions. Understanding membrane protein structure and function is vital for advancing cell biology and physiology. Experimental studies often involve extracting proteins from their native environments and reconstituting them in membrane mimetics like detergents, bicelles, amphipols, nanodiscs, and liposomes. These mimetics replicate aspects of native membranes, aiding in the study of protein behavior outside living cells. Scientists continuously explore new, more native-like membrane mimetics to improve experimental accuracy. This dynamic field involves evaluating the advantages and disadvantages of different mimetics and optimizing the reconstitution process to better mimic natural conditions.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 3","pages":"Article 184414"},"PeriodicalIF":2.8,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143363538","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 effect of oxidative stress on the adenosine A_2A receptor activity and signalling.","authors":"Idoia Company-Marín, Joseph Gunner, David Poyner, John Simms, Andrew R Pitt, Corinne M Spickett","doi":"10.1016/j.bbamem.2025.184412","DOIUrl":"https://doi.org/10.1016/j.bbamem.2025.184412","url":null,"abstract":"<p><p>The adenosine A_2A receptor (A_2AR) is a G-protein coupled receptor that has important anti-inflammatory effects in response to some agonists and consequently is considered a therapeutic target. Its activity is affected by local membrane lipid environment and presence of certain phospholipid classes, so studies should be conducted using extraction methods such as styrene maleic acid co-polymers (SMA) that retain the local lipids. Currently, little is known about the effect of oxidative stress, which may arise from inflammation, on the A_2AR. Therefore, it was over-expressed in Pichia pastoris, SMA was used to extract the A_2AR from cell membranes and its response to ligands was tested in the presence or absence of the radical initiator AAPH or reactive aldehyde acrolein. SMA-extracted A_2AR was able to undergo conformational changes, measured by tryptophan fluorescence, in response to its ligands but oxidative treatments had no effect on the structural changes. Similarly, the treatments did not affect temperature-dependent protein unfolding. In contrast, in HEK293 cells expressing the A_2AR, oxidative treatments increased cAMP levels in response to the agonist NECA but had no effect on direct activation of adenylate cyclase. Thus, oxidative stress may be a homeostatic mechanism that abrogates inflammation via the A_2AR signalling pathway.</p>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":" ","pages":"184412"},"PeriodicalIF":2.8,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143254486","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":"Tuning expression of GPCRs for the secretory pathway in the baculovirus-insect cell expression system","authors":"Jakob Aastrup Jørgensen","doi":"10.1016/j.bbamem.2024.184397","DOIUrl":"10.1016/j.bbamem.2024.184397","url":null,"abstract":"<div><div>The overexpression of G-protein-coupled receptors (GPCRs) remains one of the biggest hurdles for structural studies of these proteins. To date, the most usually applied system for this task is the insect cell/baculovirus expression system. A drawback of this system, however, is the accumulation of protein that is resistant to solubilization with the commonly used mild detergent DoDecylMaltoside (DDM). In addition, poor surface expression is often observed. In this study, it is shown how an earlier AcMNPV 39K promoter, can express receptors that are found primarily on the cell membrane, as revealed by confocal microscopy, and the protein can be solubilized to a higher degree by DDM in a less aggregation-prone form, as monitored by fluorescence size-exclusion chromatography. In addition, a strong effect on the yield was observed when the AcMNPV gp67 signal sequence was used. The documentation of the 39K promoter as an improvement over the frequently used polyhedrin promoter, along with the effect of the gp67 signal sequence are important steps toward ultimately improving the expression in terms of total functional yield, while also shedding light on the nature of the process of overproduction of membrane proteins, in particular, GPCRs.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 2","pages":"Article 184397"},"PeriodicalIF":2.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142543407","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":"Characterization of intact FeoB in a lipid bilayer using styrene-maleic acid (SMA) copolymers","authors":"Mark Lee,&nbsp;Candice M. Armstrong,&nbsp;Aaron T. Smith","doi":"10.1016/j.bbamem.2024.184404","DOIUrl":"10.1016/j.bbamem.2024.184404","url":null,"abstract":"<div><div>The acquisition of ferrous iron (Fe²⁺) is crucial for the survival of many pathogenic bacteria living within acidic and/or anoxic conditions such as <em>Vibrio cholerae</em>, the causative agent of the disease cholera. Bacterial pathogens utilize iron as a cofactor to drive essential metabolic processes, and the primary prokaryotic Fe²⁺ acquisition mechanism is the ferrous iron transport (Feo) system. In <em>V. cholerae</em>, the Feo system comprises two cytosolic proteins (FeoA, FeoC) and a complex, polytopic transmembrane protein (FeoB) that is regulated by an N-terminal soluble domain (NFeoB) with promiscuous NTPase activity. While the soluble components of the Feo system have been frequently studied, very few reports exist on the intact membrane protein FeoB. Moreover, FeoB has been characterize almost exclusively in detergent micelles that can cause protein misfolding, disrupt protein oligomerization, and even dramatically alter protein function. As many of these characteristics of FeoB remain unclear, there is a critical need to characterize FeoB in a more native-like lipid environment. To address this unmet need, we employ styrene-maleic acid (SMA) copolymers to isolate and to characterize <em>V. cholerae</em> FeoB (<em>Vc</em>FeoB) encapsulated by a styrene-maleic acid lipid particle (SMALP). In this work, we describe the development of a workflow for the expression and the purification of <em>Vc</em>FeoB in a SMALP. Leveraging mass photometry, we explore the oligomerization of FeoB in a lipid bilayer and show that the <em>Vc</em>FeoB-SMALP is mostly monomeric, consistent with our previous oligomerization observations <em>in surfo</em>. Finally, we characterize the NTPase activity of <em>Vc</em>FeoB in the SMALP and in a detergent (DDM), revealing higher NTPase activity in the presence of the lipid bilayer. When taken together, this report represents the first characterization of any FeoB in a native-like lipid bilayer and provides a viable approach for the future structural characterization of FeoB.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 2","pages":"Article 184404"},"PeriodicalIF":2.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142852335","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":"Phase-separated cationic giant unilamellar vesicles as templates for the polymerization of tetraethyl orthosilicate (TEOS)","authors":"Kohei Shiomi ,&nbsp;Keita Hayashi ,&nbsp;Haruyuki Ishii ,&nbsp;Toshiyuki Kamei ,&nbsp;Toshinori Shimanouchi ,&nbsp;Hidemi Nakamura ,&nbsp;Sosaku Ichikawa","doi":"10.1016/j.bbamem.2024.184403","DOIUrl":"10.1016/j.bbamem.2024.184403","url":null,"abstract":"<div><div>Unlike homogeneous liposomes, phase-separated liposomes have the potential to be attractive soft materials because they exhibit different properties for each phase. In this study, phase separation was observed when liposomes were prepared using 1,2-dioleoyloxy-3-trimethylammonium propane chloride (DOTAP), 1,2-distearoyl-<em>sn</em>-glycero-3-phosphocholine (DSPC), and cholesterol. The pH of the DOTAP-rich phase was evaluated using a coumarin derivative, and measurements showed that DOTAP molecules accumulated hydroxyl ions (OH⁻) in the DOTAP-rich phase. Such accumulation of OH⁻ was not observed when homogeneous DSPC liposomes were used. The difference in local concentration of OH⁻ in each phase was applied to prepare hollow silica particles with large pores. The OH⁻ promotes the polymerization of tetraethyl orthosilicate (TEOS). Therefore, TEOS polymerized preferentially in the DOTAP-rich phase, whereas a silica membrane barely formed in the DSPC-rich phase.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 2","pages":"Article 184403"},"PeriodicalIF":2.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142765765","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":"A simulation analysis of the effect of a cholesterol-dependent fusogenic peptide from HIV gp41 on membrane phospholipid dynamics","authors":"Manami Nishizawa ,&nbsp;Kazuhisa Nishizawa","doi":"10.1016/j.bbamem.2025.184413","DOIUrl":"10.1016/j.bbamem.2025.184413","url":null,"abstract":"<div><div>CpreTM is a fusogenic peptide whose N-terminal portion is derived from the membrane-proximal external region (MPER) and C-terminal portion covers the transmembrane (TM) domain of gp41 of HIV. CpreTM has been shown to induce membrane fusion, which requires cholesterol molecules as membrane components. To gain insight into the effects of CpreTM on membrane lipid dynamics, we performed molecular dynamics simulations. In conventional simulations, several cholesterol-binding sites were found under the segment derived from MPER and near the cholesterol recognition/interaction amino acid consensus (CRAC) motif located at the C-terminus of MPER. CpreTM resides in shallower positions in the POPC (palmitoyl oleoyl phosphatidylcholine)/cholesterol bilayer than in the pure POPC bilayer. Our metadynamic simulations using the position of one POPC molecule (“target POPC”) as the collective variable showed that CpreTM remarkably lowered the free energy cost for the POPC protrusion from the cholesterol-containing membrane; e.g., the cost for 0.7 nm outward displacement from the height of bulk POPC molecules was decreased by ~10 kJ/mol compared to the peptide-free corresponding system. Such stabilization of the POPC protrusion was not observed in the cholesterol-free POPC membrane. It was more pronounced near the aromatic residues, including the three Trp residues of CpreTM, suggesting important roles for aromatic residues in stabilizing the POPC protrusion.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 3","pages":"Article 184413"},"PeriodicalIF":2.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143121965","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":"Identification of a sorting motif for Tspan3 to MHCII compartments in human B cells","authors":"Fabian Schwerdtfeger ,&nbsp;Martin ter Beest ,&nbsp;Cesar A. Perez-Martinez ,&nbsp;Kris Raaijmakers ,&nbsp;Philipp Michael Hagemann ,&nbsp;Aina Martí Juan ,&nbsp;Cornelia G. Spruijt ,&nbsp;Michiel Vermeulen ,&nbsp;Sjoerd van Deventer ,&nbsp;Annemiek B. van Spriel","doi":"10.1016/j.bbamem.2024.184406","DOIUrl":"10.1016/j.bbamem.2024.184406","url":null,"abstract":"<div><div>Tetraspanins are four-transmembrane proteins that play fundamental roles in the immune system by enabling processes like migration, proliferation, signaling and protein trafficking. While the importance of cell surface tetraspanins has been established, the function of intracellular tetraspanins is less well understood. Here, we investigated the role of tetraspanin 3 (Tspan3) in lymphocytes. Tspan3 expression was low in T cells and high in B cells which increased during B cell activation. Tspan3 localized to late endosomal structures where it colocalized with major histocompatibility complex II (MHCII) in the MHCII compartment. There, inhibiting the formation of intraluminal vesicles (ILVs) showed that Tspan3 localization was not affected in contrast to its homologue CD63. Using a peptide-pulldown approach, we identified that Tspan3 interacts with AP2 via its C-terminus that harbors a YXXΦ-based sorting motif. Interestingly, mutating this motif did not impair Tspan3 localization. Instead, leucine 246 was required for its intracellular localization, identifying an unrecognized leucine-based sorting motif responsible for Tspan3 localization to MHCII compartment in B cells. Taken together, we report a new sorting motif for Tspan3 to MHCII compartments in human B cells.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 2","pages":"Article 184406"},"PeriodicalIF":2.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142845742","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":"Structural modification of lipid membranes by polyphenols: A fluorescence spectroscopy study","authors":"Valeriya M. Trusova ,&nbsp;Uliana K. Tarabara ,&nbsp;Mette H. Thomsen ,&nbsp;Galyna P. Gorbenko","doi":"10.1016/j.bbamem.2025.184411","DOIUrl":"10.1016/j.bbamem.2025.184411","url":null,"abstract":"<div><div>The present study investigates the molecular mechanisms of polyphenol-lipid interactions and their impact on membrane properties. Using pyrene and DPH as reporter molecules, we examined the impact of quercetin, curcumin, gallic, and salicylic acids on membranes composed of phosphatidylcholine (PC) and its mixtures with phosphatidylglycerol (PG), cardiolipin (CL), and cholesterol (Chol). Quercetin was found to increase the lipid order without affecting the lipid bilayer free volume, indicating interactions near the membrane surface. In turn, curcumin exhibited more complex effects, reducing free volume in PC but increasing it in PG vesicles, reflecting its amphiphilic structure and variable penetration depth. Gallic and salicylic acids selectively increased free volume at the membrane core without influencing lipid order at the upper regions of lipid bilayer. The results obtained demonstrate that polyphenol structure and lipid composition dictate the resultant pattern of polyphenol-membranes interactions, which may have implications for drug delivery and nutraceutical design.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 3","pages":"Article 184411"},"PeriodicalIF":2.8,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143036321","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":"Human cathelicidin LL-37 rapidly disrupted colonic epithelial integrity","authors":"Geeta Kilari,&nbsp;Jacquelyn Tran,&nbsp;Graham A.D. Blyth,&nbsp;Eduardo R. Cobo","doi":"10.1016/j.bbamem.2025.184410","DOIUrl":"10.1016/j.bbamem.2025.184410","url":null,"abstract":"<div><div>The intestinal barrier, held together by epithelial cells and intercellular tight junction (TJ) proteins, prevents the penetration of microbial pathogens. Concurrently, intestinal epithelial cells secrete antimicrobial peptides, including cathelicidin. Cathelicidin has direct antibacterial and immunomodulatory functions, although its role in intestinal integrity remains elusive. In this study, we demonstrate that direct stimulation of human colonic epithelial (T84) cells with human cathelicidin, LL-37, resulted in a rapid and transient increase in epithelial cell permeability. This increased permeability was associated with the TJ proteins occludin and claudin-2 degradation, mediated by these specific proteins' endocytosis and lysosomal degradation. While murine cathelicidin (CRAMP) failed to modify T84 cell permeability, LL-37 degraded TJ proteins in murine rectal epithelial (CMT-93) cells. The stimulus of (CMT-93) cells with LL-37 aggravated the cell permeability and furthered TJ degradation provoked by the intestinal pathogen, attaching/effacing (A/E) <em>Citrobacter rodentium</em> (<em>C. rodentium</em>). The number of <em>C. rodentium</em> that colonized CMT-93 cells was not severely impacted by the presence of LL-37. While a temporary disruption of tight junctions by LL-37 may lead to a ‘leaky gut,’ this study demonstrates that LL-37 increases epithelial cell permeability by degrading TJ proteins occludin and claudin-2 through endocytosis and lysosomal degradation. These immunomodulatory actions occurring at concentrations lower than those microbicidal uncover a new guise for cathelicidin modulating the epithelial barrier against A/E pathogens. Recognizing native cathelicidin's functions in a specified disease setting (e.g., colitis) will help establish it as an anti-infectious immunomodulator.</div></div>","PeriodicalId":8831,"journal":{"name":"Biochimica et biophysica acta. Biomembranes","volume":"1867 3","pages":"Article 184410"},"PeriodicalIF":2.8,"publicationDate":"2025-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142999307","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}