Biology subjects

Bhabha, G.

Publications and source records attributed to Bhabha, G..

At least 19 recordsLinked to original sources

bioRxiv2026

Live-cell imaging and ultrastructure expansion microscopy reveal the dynamic intracellular life cycle of Encephalitozoon intestinalis

Microsporidia are divergent fungal pathogens that infect a wide range of hosts. Microsporidia have evolved highly reduced genomes, resulting in the loss of many metabolic pathways. Encephalitozoon intestinalis is a human-infecting microsporidian species with the smallest known eukaryotic genome (2.3 Mbp). As an obligate intracellular parasite, E. intestinalis is dependent on its host for replication. Our current understanding of E. intestinalis cell biology remains limited. This is largely due to genetic intractability, which has made live-cell imaging challenging, and its small size (~2 m), which is within the diffraction limit of conventional microscopy. Here we develop a live-cell imaging technique, "silhouette microscopy", that does not rely on genetic manipulation of microsporidia, and enables us to study the live cell dynamics of E. intestinalis replication in host cells, from entry to exit. We report the timing of cell division, kinetics of the parasite life cycle, and dynamics of the parasitophorous vacuole within which E. intestinalis resides. The parasitophorous vacuole undergoes frequent fission and fusion, and ultimately ruptures to facilitate parasite release from the host cell. To gain a higher resolution understanding into the cell biology of E. intestinalis development, we performed ultrastructure expansion microscopy (U-ExM) on infected cells. U-ExM reveals the organization of the E. intestinalis cytoskeleton and development of the specialized invasion organelle, the polar tube. The combination of live-cell imaging and U-ExM provide a platform to study the E. intestinalis life cycle, and sheds light on the dynamics and cell biology of E. intestinalis in host cells.

microbiology↗

bioRxiv2026

Single-cell transcriptomics of Encephalitozoon intestinalis infection in Caco-2 and Vero cells

Microsporidia are single-celled, obligate intracellular parasites closely related to fungi. One of the most common human-infecting microsporidian species, Encephalitozoon intestinalis, is an enteric parasite that invades and replicates within the epithelial lining of the small intestine. Two epithelial cell lines, Caco-2 and Vero cells, are routinely used as in vitro models of E. intestinalis infection. Here, we use scRNA-seq to investigate the host response to E. intestinalis infection and the transcriptional dynamics of parasite development in both Caco-2 and Vero cell lines. We observe that most host cells have no direct transcriptional response to parasite invasion or intracellular replication, suggesting that cells fail to detect and/or fail to respond to direct E. intestinalis infection, consistent with previous single-cell transcriptomics of E. intestinalis-infected macrophages. Our data suggest that a small subset of host cells detect intracellular parasites late in the life cycle, and signal to neighboring cells, leading to broad activation of a TNF-[a] response. Analysis of parasite transcripts reveals a developmental program that correlates with the morphological stages of the parasite life cycle. Together our data provide insights into a shared host transcriptional response to E. intestinalis infection and the datasets presented are a valuable resource for future studies.

microbiology↗

bioRxiv2026

Interactions of outer membrane lipoproteins P. aeruginosa PA3214 and E. coli PqiC with their MCE protein binding partners, PA3213 and PqiB

Members of the Mammalian Cell Entry (MCE) superfamily interact with other proteins to form diverse architectures for the transport of hydrophobic molecules across the cell envelope in Gram-negative bacteria. Some of these trans-envelope MCE protein complexes include a PqiC-like outer membrane (OM) lipoprotein component. The best-studied member of this group of OM lipoproteins is E. coli PqiC, from the PqiABC system, which can form an octameric ring. How PqiC-like lipoproteins interact with their MCE protein binding partners to facilitate transport is not well understood. Here we report the cryo-electron microscopy structures of Pseudomonas aeruginosa PA3214, a homolog of PqiC, in the context of the full MCE transport PA3211-PA3214 system. Our structure provides insight into the biological assembly of the lipoprotein and interactions with its binding partner, MCE protein PA3213. We utilize deep mutational scanning to identify functionally important sites in E. coli PqiC in an unbiased manner. Through phenotypic and biochemical experiments, we characterize the interactions of the lipoproteins PqiC and PA3214 with their associated MCE proteins PqiB and PA3213, thus providing a model for how some MCE proteins employ a C-terminal peptide to mediate key interactions with their cognate lipoproteins at the OM.

microbiology↗

bioRxiv2025

Polar tube firing dynamics and ultrastructure from the shrimp microsporidian Ecytonucleospora hepatopenaei (EHP)

Ecytonucleospora (Enterocytozoon) hepatopenaei or EHP is an obligate intracellular parasite that belongs to phylum Microsporidia. EHP infection in shrimp results in growth retardation and size variation, leading to severe economic loss to shrimp aquaculture worldwide. Similar to other microsporidian species, EHP utilizes a harpoon-like invasion apparatus called the polar tube in order to infect host cells. The polar tube typically coils inside the spore and rapidly transits to a long, extended tube after being activated with proper stimuli. However, the mechanism and physical conditions affecting the polar tube firing in EHP are poorly understood. Here, we screened several germination buffers and found that a buffer containing potassium hydrogen phthalate (KHP) at pH 3.0 yielded the highest germination rate. The optimal temperatures for EHP germination range between 25-28{degrees}C, similar to the shrimps body temperature. The spores require at least 30 seconds to be activated, suggesting that the stimuli could rapidly move across the spore wall. We utilized high-speed live-cell imaging to study the dynamics of the EHP polar tube firing and compared the dynamics when the spores were treated with KHP and a previously reported stimulus, phloxine B. The polar tube firing dynamics between these two conditions are different. The total firing time was [~]100 milliseconds with the maximum velocity of [~]300 m*s-1 in KHP condition. Further investigation on the EHP polar tube ultrastructure using cryo-electron microscopy revealed that the EHP polar tube was composed of a membrane layer with an additional repetitive protein-array on the outermost surface. The distance between each repetitive unit ranges between 52-66 [A]. These repetitive units could possibly be polar tube proteins (PTPs). Altogether, this study provides insights into EHP polar tube firing dynamics and its architecture which are important foundations for understanding the biophysical factors governing EHP pathogenesis and in developing EHP control strategies. Author summaryThe microsporidian Ecytonucleospora hepatopenaei (EHP) poses a significant threat to global shrimp aquaculture, causing substantial economic losses. Many studies on EHP have been focused on development of detection methods, and farm management. Little is known about EHP pathogenesis and how it infects shrimp cells. Here, we identified laboratory conditions to activate the parasites infection process, which occurs on a millisecond timescale. We utilized a high-speed live-cell imaging to further characterize the rapid EHP infection process. The architecture and ultrastructure of EHP invasion organelle were also investigated using cryo-electron microscopy. Our findings provide a better understanding of the EHP infection mechanisms that are crucial for developing effective control strategies.

microbiology↗

bioRxiv2025

LetA defines a structurally distinct transporter family involved in lipid trafficking

Membrane transport proteins translocate diverse cargos, ranging from small sugars to entire proteins, across cellular membranes. A few structurally distinct protein families have been described that account for most of the known membrane transport processes. However, many membrane proteins with predicted transporter functions remain uncharacterized. We determined the structure of E. coli LetAB, a phospholipid transporter involved in outer membrane integrity, and found that LetA adopts a distinct architecture that is structurally and evolutionarily unrelated to known transporter families. LetA functions as a pump at one end of a ~225 [A] long tunnel formed by its binding partner, MCE protein LetB, creating a pathway for lipid transport between the inner and outer membranes. Unexpectedly, the LetA transmembrane domains adopt a fold that is evolutionarily related to the eukaryotic tetraspanin family of membrane proteins, including TARPs and claudins. LetA has no detectable homology to known transport proteins, and defines a new class of membrane transporters. Through a combination of deep mutational scanning, molecular dynamics simulations, AlphaFold-predicted alternative states, and functional studies, we present a model for how the LetA-like family of membrane transporters may use energy from the proton-motive force to drive the transport of lipids across the bacterial cell envelope.

biophysics↗

bioRxiv2024

Bond-centric modular design of protein assemblies

We describe a modular bond-centric approach to protein nanomaterial design inspired by the rich diversity of chemical structures that can be generated from the small number of atomic valencies and bonding interactions. We design protein building blocks with regular coordination geometries and bonding interactions that enable the assembly of a wide variety of closed and opened nanomaterials using simple geometrical principles. Experimental characterization confirms successful formation of more than twenty multi-component polyhedral protein cages, 2D arrays, and 3D protein lattices, with a high (10-50 %) success rate and electron microscopy data closely matching the corresponding design models. Because of the modularity, individual building blocks can assemble with different partners to generate distinct regular assemblies, resulting in an economy of parts and enabling the construction of reconfigurable systems.

biochemistry↗

bioRxiv2024

Cryo-ET reveals the in situ architecture of the polar tube invasion apparatus from microsporidian parasites

Microsporidia are divergent fungal pathogens that employ a harpoon-like apparatus called the polar tube (PT) to invade host cells. The PT architecture and its association with neighboring organelles remain poorly understood. Here, we use cryo-electron tomography to investigate the structural cell biology of the PT in dormant spores from the human-infecting microsporidian species, Encephalitozoon intestinalis. Segmentation and subtomogram averaging of the PT reveal at least four layers: two protein-based layers surrounded by a membrane, and filled with a dense core. Regularly spaced protein filaments form the structural skeleton of the PT. Combining cryo-electron tomography with cellular modeling, we propose a model for the 3-dimensional organization of the polaroplast, an organelle that is continuous with the membrane layer that envelops the PT. Our results reveal the ultrastructure of the microsporidian invasion apparatus in situ, laying the foundation for understanding infection mechanisms.

microbiology↗

bioRxiv2024

scRNA-seq reveals transcriptional dynamics of Encephalitozoon intestinalis parasites in human macrophages

Microsporidia are single-celled intracellular parasites that cause opportunistic diseases in humans. Encephalitozoon intestinalis is a prevalent human-infecting species that invades the small intestine. Dissemination to other organ systems is also observed, and is potentially facilitated by macrophages. The macrophage response to infection and the developmental trajectory of the parasite are not well studied. Here we use single cell RNA sequencing to investigate transcriptional changes in both the host and parasite during infection. While a small population of infected macrophages mount a response, most remain transcriptionally unchanged, suggesting that the majority of parasites may avoid host detection. The parasite transcriptome reveals large transcriptional changes throughout the life cycle, providing a blueprint for parasite development. The stealthy microsporidian lifestyle likely allows these parasites to harness macrophages for replication and dissemination. Together, our data provide insights into the host response in primary human macrophages and the E. intestinalis developmental program.

microbiology↗

bioRxiv2024

Identification of a proteolysis regulator for an essential enzyme in Mycobacterium tuberculosis

In Mycobacterium tuberculosis proteins that are post-translationally modified with Pup, a prokaryotic ubiquitin-like protein, can be degraded by proteasomes. While pupylation is reversible, mechanisms regulating substrate specificity have not been identified. Here, we identify the first depupylation regulators: CoaX, a pseudokinase, and pantothenate, an essential, central metabolite. In a {Delta}coaX mutant, pantothenate synthesis enzymes were more abundant, including PanB, a substrate of the Pup-proteasome system. Media supplementation with pantothenate decreased PanB levels in a coaX and Pup-proteasome-dependent manner. In vitro, CoaX accelerated depupylation of Pup[~]PanB, while addition of pantothenate inhibited this reaction. Collectively, we propose CoaX contributes to proteasomal degradation of PanB by modulating depupylation of Pup[~]PanB in response to pantothenate levels. One Sentence SummaryA pseudo-pantothenate kinase regulates proteasomal degradation of a pantothenate synthesis enzyme in M. tuberculosis.

microbiology↗

bioRxiv2023

Conformational states of the microtubule nucleator, the γ-tubulin ring complex

Microtubules (MTs) perform essential functions in the cell, and it is critical that they are made at the correct cellular location and cell cycle stage. This nucleation process is catalyzed by the {gamma}-tubulin ring complex ({gamma}-TuRC), a cone-shaped protein complex composed of over 30 subunits. Despite recent insight into the structure of vertebrate {gamma}-TuRC, which shows that its diameter is wider than that of a MT, and that it exhibits little of the symmetry expected for an ideal MT template, the question of how {gamma}-TuRC achieves MT nucleation remains open. Here, we utilized single particle cryo-EM to identify two conformations of {gamma}-TuRC. The helix composed of 14 {gamma}-tubulins at the top of the {gamma}-TuRC cone undergoes substantial deformation, which is predominantly driven by bending of the hinge between the GRIP1 and GRIP2 domains of the {gamma}-tubulin complex proteins. However, surprisingly, this deformation does not remove the inherent asymmetry of {gamma}-TuRC. To further investigate the role of {gamma}-TuRC conformational change, we used cryo electron-tomography (cryo-ET) to obtain a 3D reconstruction of {gamma}-TuRC bound to a nucleated MT, providing insight into the post-nucleation state. Rigid-body fitting of our cryo-EM structures into this reconstruction suggests that the MT lattice is nucleated by spokes 2 through 14 of the {gamma}-tubulin helix, which entails spokes 13 and 14 becoming more structured than what is observed in apo {gamma}-TuRC. Together, our results allow us to propose a model for conformational changes in {gamma}-TuRC and how these may facilitate MT formation in a cell.

molecular biology↗

bioRxiv2023

Discovery of a novel inhibitor of macropinocytosis with antiviral activity

Several viruses hijack various forms of endocytosis in order to infect host cells. Here, we report the discovery of a new molecule with antiviral properties that we named virapinib, which limits viral entry by macropinocytosis. The identification of virapinib derives from a chemical screen using High-Throughput Microscopy, where we identified new chemical entities capable of preventing infection with a pseudotype virus expressing the spike (S) protein from SARS-CoV-2. Subsequent experiments confirmed the capacity of virapinib to inhibit infection by SARS-CoV-2, as well as by additional viruses, such as Monkeypox virus and TBEV. Mechanistic analyses revealed that the compound inhibited macropinocytosis, limiting this entry route for the viruses. Importantly, virapinib has no significant toxicity to host cells. In summary, we present a new molecule that inhibits viral entry via the endocytic route, offering a new alternative to prevent viral infection.

pharmacology and toxicology↗

bioRxiv2023

Phospholipid transport to the bacterial outer membrane through an envelope-spanning bridge

The outer membrane of Gram-negative bacteria provides a formidable barrier, essential for both pathogenesis and antimicrobial resistance. Biogenesis of the outer membrane requires the transport of phospholipids across the cell envelope. Recently, YhdP was implicated as a major protagonist in the transport of phospholipids from the inner membrane to the outer membrane however the molecular mechanism of YhdP mediated transport remains elusive. Here, utilising AlphaFold, we observe YhdP to form an elongated assembly of 60 {beta} strands that curve to form a continuous hydrophobic groove. This architecture is consistent with our negative stain electron microscopy data which reveals YhdP to be approximately 250 [A] in length and thus sufficient to span the bacterial cell envelope. Furthermore, molecular dynamics simulations and in vivo bacterial growth assays indicate essential helical regions at the N- and C-termini of YhdP, that may embed into the inner and outer membranes respectively, reinforcing its envelope spanning nature. Our in vivo crosslinking data reveal phosphate-containing substrates captured along the length of the YhdP groove, providing direct evidence that YhdP transports phospholipids. This finding is congruent with our molecular dynamics simulations which demonstrate the propensity for inner membrane lipids to spontaneously enter the groove of YhdP. Collectively, our results support a model in which YhdP bridges the cell envelope, providing a hydrophobic environment for the transport of phospholipids to the outer membrane.

microbiology↗

bioRxiv2023

Sample preparation and data collection for Serial Block Face Scanning Electron Microscopy of Mammalian Cell Monolayers

Volume electron microscopy encompasses a set of electron microscopy techniques that can be used to examine the ultrastructure of biological tissues and cells in three dimensions. Two block face techniques, focussed ion beam scanning electron microscopy (FIB-SEM) and serial block face scanning electron microscopy (SBF-SEM) have often been used to study biological tissue samples. More recently, these techniques have been adapted to in vitro tissue culture samples. Here we describe detailed protocols for two sample embedding methods for in vitro tissue culture cells intended to be studied using SBF-SEM. The first protocol focuses on cell pellet embedding and the second on en face embedding. En face embedding can be combined with light microscopy, and this CLEM workflow can be used to identify specific biological events in a light microscope, which can then be imaged using SBF-SEM. We systematically outline the steps necessary to fix, stain, embed and image adherent tissue culture cell monolayers by SBF-SEM. In addition to sample preparation, we discuss optimization of parameters for data collection. We highlight the challenges and key steps of sample preparation, and the consideration of imaging variables that will facilitate the acquisition of high quality datasets. Users experienced with electron microscopy sample preparation methodology will be able to complete this protocol in 10-11 days from initial seeding of cells in tissue culture to image acquisition.

cell biology↗

bioRxiv2023

3D reconstructions of parasite development and the intracellular niche of the microsporidian pathogen E. intestinalis

Microsporidia are an early-diverging group of fungal pathogens that infect a wide range of hosts. Several microsporidian species infect humans, and infections can lead to fatal disease in immunocompromised individuals. As obligate intracellular parasites with highly reduced genomes, microsporidia are dependent on metabolites from their hosts for successful replication and development. Our knowledge of how microsporidian parasites develop inside the host remains rudimentary, and our understanding of the intracellular niche occupied by microsporidia has thus far relied largely on 2D TEM images and light microscopy. Here, we use serial block face scanning electron microscopy (SBF-SEM) to capture 3D snapshots of the human-infecting microsporidian, Encephalitozoon intestinalis, within host cells. We track the development of E. intestinalis through its life cycle, which allows us to propose a model for how its infection organelle, the polar tube, is assembled de novo in each developing spore. 3D reconstructions of parasite-infected cells provide insights into the physical interactions between host cell organelles and parasitophorous vacuoles, which contain the developing parasites. The host cell mitochondrial network is substantially remodeled during E. intestinalis infection, leading to mitochondrial fragmentation. SBF-SEM analysis shows changes in mitochondrial morphology in infected cells, and live-cell imaging provides insights into mitochondrial dynamics during infection. Together, our data provide insights into parasite development, polar tube assembly, and microsporidia-induced mitochondrial remodeling in the host cell.

microbiology↗

bioRxiv2023

Blueprinting expandable nanomaterials with standardized protein building blocks

A wooden house frame consists of many different lumber pieces, but because of the regularity of these building blocks, the structure can be designed using straightforward geometrical principles. The design of multicomponent protein assemblies in comparison has been much more complex, largely due to the irregular shapes of protein structures1. Here we describe extendable linear, curved, and angled protein building blocks, as well as inter-block interactions that conform to specified geometric standards; assemblies designed using these blocks inherit their extendability and regular interaction surfaces, enabling them to be expanded or contracted by varying the number of modules, and reinforced with secondary struts. Using X-ray crystallography and electron microscopy, we validate nanomaterial designs ranging from simple polygonal and circular oligomers that can be concentrically nested, up to large polyhedral nanocages and unbounded straight "train track" assemblies with reconfigurable sizes and geometries that can be readily blueprinted. Because of the complexity of protein structures and sequence-structure relationships, it has not been previously possible to build up large protein assemblies by deliberate placement of protein backbones onto a blank 3D canvas; the simplicity and geometric regularity of our design platform now enables construction of protein nanomaterials according to "back of an envelope" architectural blueprints.

biochemistry↗

bioRxiv2023

Modulation of FGF pathway signaling and vascular differentiation using designed oligomeric assemblies

Growth factors and cytokines signal by binding to the extracellular domains of their receptors and drive association and transphosphorylation of the receptor intracellular tyrosine kinase domains, initiating downstream signaling cascades. To enable systematic exploration of how receptor valency and geometry affects signaling outcomes, we designed cyclic homo-oligomers with up to 8 subunits using repeat protein building blocks that can be modularly extended. By incorporating a de novo designed fibroblast growth-factor receptor (FGFR) binding module into these scaffolds, we generated a series of synthetic signaling ligands that exhibit potent valency- and geometry-dependent Ca2+ release and MAPK pathway activation. The high specificity of the designed agonists reveal distinct roles for two FGFR splice variants in driving endothelial and mesenchymal cell fates during early vascular development. The ability to incorporate receptor binding domains and repeat extensions in a modular fashion makes our designed scaffolds broadly useful for probing and manipulating cellular signaling pathways. HighlightsO_LIDe novo designed cyclic oligomers with tunable geometric properties C_LIO_LICyclic, homo-oligomeric FGFR binding modules induce geometry- and valency-dependent activity of isoform-specific FGF signaling C_LIO_LIModulation of FGFR isoform activity controls bifurcation of endothelial and mesenchymal fate during vascular development C_LIO_LIC-isoform activation favors arterial endothelial cell formation while B-isoform induces pericyte differentiation C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=135 SRC="FIGDIR/small/532666v1_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@151f6eforg.highwire.dtl.DTLVardef@2ae877org.highwire.dtl.DTLVardef@103e0d1org.highwire.dtl.DTLVardef@19cd695_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2023

Energetics of the Microsporidian Polar Tube Invasion Machinery

Microsporidia are eukaryotic, obligate intracellular parasites that infect a wide range of hosts, leading to health and economic burdens worldwide. Microsporidia use an unusual invasion organelle called the polar tube (PT), which is ejected from a dormant spore at ultra-fast speeds, to infect host cells. The mechanics of PT ejection are impressive. Anncaliia algerae microsporidia spores (3-4 {micro}m in size) shoot out a 100-nm-wide PT at a speed of 300 {micro}m/sec, creating a shear rate of 3000 sec-1. The infectious cargo, which contains two nuclei, is shot through this narrow tube for a distance of [~]60-140 {micro}m (Jaroenlak et al., 2020) and into the host cell. Considering the large hydraulic resistance in an extremely thin tube and the low-Reynolds-number nature of the process, it is not known how microsporidia can achieve this ultrafast event. In this study, we use Serial Block-Face Scanning Electron Microscopy to capture 3-dimensional snapshots of A. algerae spores in different states of the PT ejection process. Grounded in these data, we propose a theoretical framework starting with a systematic exploration of possible topological connectivity amongst organelles, and assess the energy requirements of the resulting models. We perform PT ring experiments in media of varying viscosity, and use the results to rank our proposed hypotheses based on their predicted energy requirement. We also present a possible mechanism for cargo translocation, and quantitatively compare our predictions to experimental observations. Our study provides a comprehensive biophysical analysis of the energy dissipation of microsporidian infection process and demonstrates the extreme limits of cellular hydraulics. Statement of SignicanceMicrosporidia are a group of spore-forming, intracellular parasites that infect a wide range of hosts (including humans). Once triggered, microsporidian spores (3-4 {micro}m in size) shoot out a specialized organelle called the polar tube (PT) (60-140 {micro}m long, 100 nm wide) at ultrafast speed (300 {micro}m/sec), penetrating host cells and acting as a conduit for the transport of infectious cargo. Although this process has fascinated biologists for a century, the biophysical mechanisms underlying PT extrusion are not understood. We thus take a data-driven approach to generate models for the physical basis of PT ring and cargo transport through the PT. Our approach here demonstrates the extreme limits of cellular hydraulics and the potential applications of biophysical approaches to other cellular architectures.

biophysics↗

bioRxiv2022

Protein-protein interactions in the Mla lipid transport system probed by computational structure prediction and deep mutational scanning

The outer membrane (OM) of Gram-negative bacteria is an asymmetric bilayer that protects the cell from various external stressors, such as antibiotics. The Mla transport system is implicated in the Maintenance of outer membrane Lipid Asymmetry and is thought to mediate retrograde phospholipid transport across the cell envelope. This system uses a shuttle-like mechanism to move lipids between the MlaFEDB inner membrane complex and the MlaA-OmpF/C OM complex, via a periplasmic lipid-binding protein, MlaC. MlaC binds to MlaD and MlaA, but the underlying protein-protein interactions that facilitate lipid transfer are not well understood. Here, we take an unbiased deep mutational scanning approach to map the fitness landscape of MlaC, which provides insights into important functional sites. Combining this analysis with AlphaFold2 structure predictions and binding experiments, we map the MlaC-MlaA and MlaC-MlaD protein-protein interfaces. Our results suggest that the MlaD and MlaA binding surfaces on MlaC overlap to a large extent, leading to a model in which MlaC can only bind one of these proteins at a time. Low-resolution cryo-electron microscopy (cryo-EM) maps of MlaC bound to MlaFEDB suggest that at least two MlaC molecules can bind to MlaD at once, in a conformation consistent with AlphaFold2 predictions. These data lead us to a model for MlaC interaction with its binding partners and insights into lipid transfer steps that underlie phospholipid transport between the inner and outer membranes.

biophysics↗