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| Open AccessSTIM-Orai1 signaling regulates fluidity of cytoplasm during membrane blebbing
The cytoplasm in mammalian cells is considered homogeneous. Here authors report that the cytoplasmic fluidity is regulated in the blebbing cells, which is regulated by calcium concentration in the expanding blebs and involves the STIM-Orai1 pathway.
- Kana Aoki
- , Shota Harada
- & Junichi Ikenouchi
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Article
| Open AccessNanoscale imaging of bacterial infections by sphingolipid expansion microscopy
Imaging of lipid bilayers using light microscopy is challenging. Here the authors label cells using a short chain click-compatible ceramide to visualize mammalian and bacterial membranes with expansion microscopy.
- Ralph Götz
- , Tobias C. Kunz
- & Markus Sauer
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Article
| Open AccessConnexin-46/50 in a dynamic lipid environment resolved by CryoEM at 1.9 Å
The local lipid environment is known to affect the structure, stability and intercellular channel activity of gap junctions, however, the molecular basis for these effects remains unknown. Here authors report the CryoEM structure of Cx46/50 lipid-embedded channels, by which they reveal a lipid-induced stabilization to the channel.
- Jonathan A. Flores
- , Bassam G. Haddad
- & Steve L. Reichow
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Article
| Open AccessCryo-EM structures of intact V-ATPase from bovine brain
The vacuolar-type H+ -ATPases (V-ATPase) hydrolyze ATP to pump protons across the plasma or intracellular membrane. Here authors report two cryo-EM structures of the intact V-ATPase from bovine brain with all the subunits including the subunit H, which is essential for ATPase activity.
- Rong Wang
- , Tao Long
- & Xiaochun Li
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Article
| Open AccessContacting domains segregate a lipid transporter from a solute transporter in the malarial host–parasite interface
While membrane contact sites between intracellular organelles are abundant, little is known about the contacts between membranes that delimit extracellular junctions within cells, such as intracellular parasites. Here authors demonstrate the segregation of a lipid transporter from a solute transporter in the malarial host-parasite interface.
- Matthias Garten
- , Josh R. Beck
- & Joshua Zimmerberg
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Article
| Open AccessAβ(1-42) tetramer and octamer structures reveal edge conductivity pores as a mechanism for membrane damage
Formation of amyloid-beta (Aβ) oligomer pores in the membrane of neurons has been proposed to explain neurotoxicity in Alzheimer´s disease. Here authors present the 3D- structure of an Aβ oligomer formed in a membrane mimicking environment and observe that Aβ tetramers and octamers inserted into lipid bilayers as well-defined pores.
- Sonia Ciudad
- , Eduard Puig
- & Natàlia Carulla
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Article
| Open AccessHuman ESCRT-III polymers assemble on positively curved membranes and induce helical membrane tube formation
ESCRT-III complexes assemble in vivo inside membrane structures with a negative Gaussian curvature, but how membrane shape influences ESCRT-III polymerization remains unclear. Here authors use structural and biophysical methods to show how human ESCRT-III polymers assemble on positively curved membranes and induce helical membrane tube formation.
- Aurélie Bertin
- , Nicola de Franceschi
- & Patricia Bassereau
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| Open AccessPrimary cell wall inspired micro containers as a step towards a synthetic plant cell
Assembling synthetic plant cell is difficult due to the presence of primary cell wall. Here, the authors describe the assembly of lipid-containing bodies that can be coated with cellulose and pectin, and show how these so-called plantosomes can be manipulated by changing surrounding milieu.
- T. Paulraj
- , S. Wennmalm
- & A. J. Svagan
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Article
| Open AccessRegulation of lipid saturation without sensing membrane fluidity
Cells maintain membrane fluidity by regulating lipid saturation, but the molecular mechanisms of this homeoviscous adaptation remain poorly understood. Here authors reconstituted the core machinery for regulating lipid saturation in baker’s yeast to directly characterize its response to defined membrane environments and uncover its mode-of-action.
- Stephanie Ballweg
- , Erdinc Sezgin
- & Robert Ernst
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Article
| Open AccessProgrammed magnetic manipulation of vesicles into spatially coded prototissue architectures arrays
To execute higher-order functions, cells self-assemble into spatially coded tissue configurations. Here the authors magnetically assembly giant unilamellar vesicles into three dimensional tissue-mimic structures with collective osmotic stability.
- Qingchuan Li
- , Shubin Li
- & Xiaojun Han
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Article
| Open AccessAnnexin-V stabilizes membrane defects by inducing lipid phase transition
Annexins are cytoplasmic proteins, which bind to membranes exposing negatively charged phospholipids in a Ca2+-dependent manner. Here the authors use high-speed atomic force microscopy and other techniques to show that annexin-V self-assembles into highly structured lattices that lead to a membrane phase transition on PS-rich membranes.
- Yi-Chih Lin
- , Christophe Chipot
- & Simon Scheuring
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Article
| Open AccessPhagocytosis is mediated by two-dimensional assemblies of the F-BAR protein GAS7
The Bin/Amphiphysin/Rvs167 (BAR) domain superfamily, which includes FCH-BAR (F-BAR) domain proteins are membrane-sculpting proteins. Here the authors combine a range of techniques and show that the F-BAR domain of growth-arrest specific protein 7 (GAS7) forms two-dimensional sheets on flat membranes and that these oligomeric assemblies of GAS7 are required for the formation of phagocytic cups in macrophages.
- Kyoko Hanawa-Suetsugu
- , Yuzuru Itoh
- & Shiro Suetsugu
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Article
| Open AccessMetal-coordinated sub-10 nm membranes for water purification
Ultrathin membranes have demonstrated great promise for water purification technologies owing to their high permeance. Here the authors fabricate sub-10 nm, defect-free, robust membranes for dye remediation from water through the coordination-driven assembly of metal-organophosphates.
- Xinda You
- , Hong Wu
- & Zhongyi Jiang
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Article
| Open AccessHigh-speed AFM height spectroscopy reveals µs-dynamics of unlabeled biomolecules
The dynamics of biomolecules can occur over a wide range of time and length scales. Here the authors develop a high-speed AFM height spectroscopy method to directly detect the motion of unlabeled molecules at Angstrom spatial and microsecond temporal resolution.
- George R. Heath
- & Simon Scheuring
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Article
| Open AccessSculpting and fusing biomimetic vesicle networks using optical tweezers
Assembly of higher-order artificial vesicles can unlock new applications. Here, the authors use optical tweezers to construct user-defined 2D and 3D architectures of chemically distinct vesicles and demonstrate inter-vesicle communication and light-enabled compartment merging.
- Guido Bolognesi
- , Mark S. Friddin
- & Yuval Elani
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| Open AccessIntermembrane crosstalk drives inner-membrane protein organization in Escherichia coli
Outer membrane proteins (OMPs) in Gram-negative bacteria have restricted lateral mobility. Here, Rassam et al. show that the bacteriocin ColE9, via its interactions with OMPs, imposes this restricted mobility on the inner membrane proteins of the Tol-Pal complex.
- Patrice Rassam
- , Kathleen R. Long
- & Colin Kleanthous
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Article
| Open AccessNanoscale kinetic segregation of TCR and CD45 in engaged microvilli facilitates early T cell activation
T cell activation is critically controlled by T cell receptor (TCR) signalling. Here the authors show, using live cell imaging, atomic force microscopy and modelling simulation, a prompt separation of TCR and CD45 that negatively correlates with TCR activation, supporting a refined kinetic segregation model of TCR signalling.
- Yair Razvag
- , Yair Neve-Oz
- & Eilon Sherman
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| Open AccessDiscovery and characterization of stable and toxic Tau/phospholipid oligomeric complexes
The Alzheimer protein Tau interacts with biological membranes, but the role of these interactions in regulating Tau function in health and disease remains unexplored. Here, the authors report on the discovery and characterization of neurotoxic oligomeric protein/phospholipid complexes.
- Nadine Ait-Bouziad
- , Guohua Lv
- & Hilal A. Lashuel
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Article
| Open AccessStructural determinants and functional consequences of protein affinity for membrane rafts
Lipid rafts are plasma membrane domains that specifically recruit particular proteins. Here, the authors show that the surface area, length and palmitoylation of single-pass transmembrane domains are crucial for raft partitioning and propose a general model to predict protein association with rafts.
- Joseph H. Lorent
- , Blanca Diaz-Rohrer
- & Ilya Levental
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| Open AccessStructural and functional insights into the lipopolysaccharide ABC transporter LptB2FG
Lipopolysaccharides (LPS) are synthesized at the periplasmic side of the inner membrane of Gram-negative bacteria and are then extracted by the LptB2FG complex during the first step of LPS transport to the outer membrane. Here the authors present the LptB2FG structure, which supports an alternating lateral access mechanism for LPS extraction.
- Haohao Dong
- , Zhengyu Zhang
- & Changjiang Dong
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Article
| Open AccessAgonist-induced dimer dissociation as a macromolecular step in G protein-coupled receptor signaling
Frizzled 6 (FZD6) is a G protein-coupled receptor (GPCR) involved in several cellular processes. Here, the authors use live cell imaging and spectroscopy to show that FZD6 forms dimers, whose association is regulated by WNT proteins and that dimer dissociation is crucial for FZD6 signaling.
- Julian Petersen
- , Shane C. Wright
- & Gunnar Schulte
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Article
| Open AccessResolving mixed mechanisms of protein subdiffusion at the T cell plasma membrane
Membrane protein diffusion is affected by distinct mechanisms such as molecular crowding and medium elasticity. Here the authors present an analytical approach to analyse single particle trajectories and distinguish mixed subdiffusive processes affecting membrane protein mobility in living cells.
- Yonatan Golan
- & Eilon Sherman
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Article
| Open AccessFronts and waves of actin polymerization in a bistability-based mechanism of circular dorsal ruffles
Circular dorsal ruffles (CDRs) are important for the vesicular uptake of extracellular matter, but the basis of their wave dynamics is not understood. Here, the authors propose and experimentally test a bistable reaction-diffusion system, which they show accounts for the typical CDR expansion and shrinkage and for aberrant formation of pinned waves and spirals.
- Erik Bernitt
- , Hans-Günther Döbereiner
- & Arik Yochelis
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Article
| Open AccessRegulated membrane remodeling by Mic60 controls formation of mitochondrial crista junctions
The MICOS complex has an essential role in crista junction formation and mitochondrial inner membrane morphology. Here, the authors show that one of its components, Mic60, known to form contact sites between inner and outer membranes, also displays membrane-shaping activity.
- Manuel Hessenberger
- , Ralf M. Zerbes
- & Oliver Daumke
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| Open AccessReal-time visualization of conformational changes within single MloK1 cyclic nucleotide-modulated channels
Some ion channels are modulated by binding of cyclic nucleotide to a cyclic nucleotide-binding domain. Here, the authors use high-speed atomic force microscopy to directly monitor the conformational changes induced by ligand binding to a cyclic nucleotide-modulated channel from Mesorhizobium loti.
- Martina Rangl
- , Atsushi Miyagi
- & Simon Scheuring
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| Open AccessMapping surface charge density of lipid bilayers by quantitative surface conductivity microscopy
Surface charges on lipid bilayers deeply influence the way proteins interact with cellular membranes, yet their precise quantification has proven challenging. Here, the authors report on a quantitative method to map and evaluate surface charge densities under physiological conditions.
- Lasse Hyldgaard Klausen
- , Thomas Fuhs
- & Mingdong Dong
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Article
| Open AccessStructural basis of transcobalamin recognition by human CD320 receptor
Cellular uptake of vitamin B12 (cobalamin) requires the binding of holo-transcobalamin (TC) from plasma by CD320. Here, the authors report the structure of a complex between CD320 and TC loaded with cyanocobalamin, alongside additional functional analysis.
- Amer Alam
- , Jae-Sung Woo
- & Kaspar P. Locher
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Article
| Open AccessWall mechanics and exocytosis define the shape of growth domains in fission yeast
Cell shape is determined by a combination of biochemical regulation and mechanical forces. By imaging the dynamic behaviour of growth regulatory proteins in fission yeast and integrating these data within a mechanical model, Abenza et al. find that exocytosis plays a dominant role in shaping growth domains.
- Juan F. Abenza
- , Etienne Couturier
- & Rafael E. Carazo Salas
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| Open AccessTwo classes of regulatory subunits coassemble in the same BK channel and independently regulate gating
Ion channels are often an assembly of proteins, but it is not clear if protein combinations have additive effects or function to prevent binding of other proteins. Here, the authors show that β and γ subunits can assemble into the same BK complex, and the constituents of the complex have an effect on its function.
- Vivian Gonzalez-Perez
- , Xiao-Ming Xia
- & Christopher J. Lingle
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Article
| Open AccessBax monomers form dimer units in the membrane that further self-assemble into multiple oligomeric species
The proapoptotic protein Bax triggers cell death by forming pores in the outer mitochondrial membrane. Using single-particle TIRF imaging, the authors show that Bax binds the membrane in a monomeric state before forming dimers and multimers of dimers, which are disassembled by the survival protein Bcl-xL.
- Yamunadevi Subburaj
- , Katia Cosentino
- & Ana J. García-Sáez
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| Open AccessIntrinsically disordered proteins drive membrane curvature
Proteins that bend membranes often contain curvature-promoting structural motifs such as wedges or crescent-shaped domains. Busch et al.report that intrinsically disordered domains can also drive membrane curvature and provide evidence that steric pressure driven by protein crowding mediates this effect.
- David J. Busch
- , Justin R. Houser
- & Jeanne C. Stachowiak
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| Open AccessPhysical principles of membrane remodelling during cell mechanoadaptation
Variations in cell shape must be accommodated by the cell membrane, but how the membrane adjusts to changes in area and volume is not known. Here the authors show that the membrane responds in a nearly instantaneous, purely physical manner involving the flattening or generation of membrane invaginations.
- Anita Joanna Kosmalska
- , Laura Casares
- & Pere Roca-Cusachs
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Article
| Open AccessMembrane tension controls the assembly of curvature-generating proteins
BAR domain proteins are known to reshape cell membranes. Using coarse-grained molecular dynamics simulations, Simunovic and Voth demonstrate that membrane tension strongly affects the association of BAR proteins, in turn controlling their recruitment to membrane-remodelling sites.
- Mijo Simunovic
- & Gregory A. Voth
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| Open AccessA common assembly module in injectisome and flagellar type III secretion sorting platforms
In bacteria, type III secretion systems (T3SS) allow the direct transport of protein across membranes, and related elements of a sorting platform facilitate hierarchical secretion of protein substrates. Here, the authors illustrate the mechanism of selective assembly of the T3SS sorting platforms in injectisome and flagellar systems.
- Ryan Q. Notti
- , Shibani Bhattacharya
- & C. Erec Stebbins
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Article
| Open AccessThe structure of FMNL2–Cdc42 yields insights into the mechanism of lamellipodia and filopodia formation
FMNL formins polymerize actin filaments to generate cellular protrusions such as lamellipodia and filopodia at the leading edge of a cell. Here the authors provide detailed mechanistic insights into the formation of actin-based protrusions through GTPase dependent activation and membrane localization of FMNL1 and FMNL2.
- Sonja Kühn
- , Constanze Erdmann
- & Matthias Geyer
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GPI-anchored proteins do not reside in ordered domains in the live cell plasma membrane
The existence of membrane rafts of higher lipid order in living cells is subject to ongoing debate. Here, Sevcsik et al. use a micropatterning approach to show that glycosylphosphatidylinositol-anchored proteins, typical raft constituents, do not influence their membrane nanoenvironment to promote raft phase formation.
- Eva Sevcsik
- , Mario Brameshuber
- & Gerhard J. Schütz
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Structure and function of lysosomal phospholipase A2 and lecithin:cholesterol acyltransferase
Lysosomal phospholipase A2 (LPLA2) and lecithin:cholesterol acyltransferase (LCAT) are important lipid metabolizing enzymes. Here the authors present crystal structures of LPLA2 and LCAT that reveal the unique architecture of this small family of enzymes involved in human physiology and disease.
- Alisa Glukhova
- , Vania Hinkovska-Galcheva
- & John J. G. Tesmer
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| Open AccessStructural basis for self-assembly of a cytolytic pore lined by protein and lipid
Actinoporins are water-soluble pore-forming toxins that self-assemble in the membranes of target cells. Here, the authors provide insight into the mechanism of membrane pore formation by solving the structures of several states of the hemolytic protein fragaceatoxin C, including the fully assembled pore.
- Koji Tanaka
- , Jose M.M. Caaveiro
- & Kouhei Tsumoto
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Article
| Open AccessThe assembly dynamics of the cytolytic pore toxin ClyA
Pore-forming toxins are expressed as monomers and assemble into multimeric pores. Here, Benke et al. follow the kinetics of pore formation for the bacterial toxin ClyA with single-molecule methods and show that pore formation progresses through the assembly of oligomeric intermediates, rather than by the addition of monomers to a nascent pore.
- Stephan Benke
- , Daniel Roderer
- & Benjamin Schuler
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Article
| Open AccessAnnexin A2 promotes phagophore assembly by enhancing Atg16L+ vesicle biogenesis and homotypic fusion
The earliest steps in autophagy are thought to include the budding of Atg16L-containing vesicles from the plasma membrane and their homotypic fusion to form a phagophore. Morozova et al. reveal a role for the membrane curvature-inducing protein Annexin A2 in the formation and fusion of these vesicles.
- Kateryna Morozova
- , Sunandini Sidhar
- & Laura Santambrogio
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Article
| Open AccessStructural basis for the facilitative diffusion mechanism by SemiSWEET transporter
SWEET family proteins mediate cellular sugar efflux and exchange through a facilitative diffusion mechanism. Here, Lee et al. shed light on the overall sugar transport cycle of the SemiSWEET uniporter-based structures trapped in both the inward-facing and outward-facing conformations.
- Yongchan Lee
- , Tomohiro Nishizawa
- & Osamu Nureki
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Phosphoinositide 3-kinase p110δ promotes lumen formation through the enhancement of apico-basal polarity and basal membrane organization
Kidney epithelial cells grown in 3D culture form polarized cysts in which basal membranes surround a lumen. Peng et al.show that the p110δ subunit of phosphoinositide 3-kinase contributes to the formation of these structures by influencing focal adhesion at the basal membrane.
- Juan Peng
- , Aline Awad
- & Ama Gassama-Diagne
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Ambidextrous binding of cell and membrane bilayers by soluble matrix metalloproteinase-12
Matrix metalloprotease-12 is secreted by macrophages during the inflammatory response, but was reported to be active near cell surfaces. Koppisetti et al.reveal the enzyme’s unprecedented use of two distinct surfaces to interact with lipid bilayers, thereby targeting it to cellular membranes.
- Rama K. Koppisetti
- , Yan G. Fulcher
- & Steven R. Van Doren
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Reconstitution of a nanomachine driving the assembly of proteins into bacterial outer membranes
The translocation and assembly module (TAM) is a nanomachine responsible for assembly of proteins into the outer membrane of pathogenic bacteria. Here, Shen et al.use magnetic contrast neutron reflectrometry to visualize movements within the TAM and insertion of a substrate protein into the lipid bilayer.
- Hsin-Hui Shen
- , Denisse L. Leyton
- & Trevor Lithgow
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A sub-nanometre view of how membrane curvature and composition modulate lipid packing and protein recruitment
Membrane curvature and lipid composition direct the binding of many peripheral membrane proteins. Here, Vanni et al. use a combination of in vitroand molecular dynamics approaches to quantify how lipid-packing defects in membranes of various composition and curvature dictate the membrane adsorption of a model lipid-binding protein.
- Stefano Vanni
- , Hisaaki Hirose
- & Romain Gautier
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| Open AccessMulti-protein assemblies underlie the mesoscale organization of the plasma membrane
Although many proteins adopt uneven distributions in the plasma membrane, it is not clear how these nanoscale heterogeneities relate to the general protein patterning of the membrane. Saka et al. use click chemistry to reveal the mesoscale organization of membrane proteins into multi-protein assemblies.
- Sinem K. Saka
- , Alf Honigmann
- & Silvio O. Rizzoli
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| Open AccessStructure and Scm3-mediated assembly of budding yeast centromeric nucleosomes
There is debate about the structural organization of the yeast centromeric nucleosome and the role of the nonhistone protein Scm3 in its assembly. Dechassaet al.find that yeast centromeric nucleosomes organize DNA in a left-handed superhelix, and show that Scm3 is a specific nucleosome assembly factor.
- Mekonnen Lemma Dechassa
- , Katharina Wyns
- & Karolin Luger