No abstract

significant effect of the toxin is found, possibly related to decreased lipid mobility [4]. Here we will provide an overview of membrane texture in a range of systems and describe our efforts to understand and systematize the observations.[1] JACS (2009). Giant plasma membrane vesicles (GPMVs) isolated from mammalian cell lines contain coexisting liquid phases at low temperature, a single liquid phase at elevated temperatures, and undergo robust micron-sized critical fluctuations near the miscibility transition which is typically close to room temperature. In past work, we have measured the temperature dependence of critical composition fluctuations and speculated that mammalian cells tune their membrane composition to maintain a room temperature critical point in order to experience <100nm super-critical composition fluctuations under growth conditions of 37 C [1]. Here, we present evidence that cells actively tune membrane critical temperatures (Tc) to a specific temperature difference below growth temperatures by preparing GPMVs from ZF4 cells, a zebrafish cell line that is capable of growing at temperatures ranging between 20 and 32 C. As was the case in mammalian cell lines, ZF4 cells produce GPMVs with coexisting liquid phases at low temperature and micron-sized critical fluctuations near the miscibility transition. ZF4 derived GPMVs transition temperatures shift to lower values when cells are grown at lower temperature,

ATP flux. Therefore, we determined the conduction state of the channel with regard to the ATP permeation. To understand ATP permeation through VDAC, we solved the structure of murine VDAC1 (mVDAC1) in the presence of ATP revealing a low-occupancy binding site. Guided by these coordinates, we initiated hundreds of molecular dynamics (MD) simulations to construct a Markov State Model (MSM) of ATP permeation using the software (Beauchamp et al. JCTC 2011). These simulations show a high ATP flux generated from multiple pathways through the channel, consistent with our structural data and previously reported physiological permeation rates. 'Flucs' are small membrane proteins widespread in bacteria, single-celled eukaryotes, and plants. Only recently characterized, Flucs act as fluoride-specific ion channels, forming antiparallel dimers of four-helix transmembrane bundles. Little else is known about this protein family. To gain insight into the structure and function of the Flucs, we use direct-coupling analysis (DCA) and ab initio molecular modeling to generate all-atom models of the E. coli Fluc homodimer EC2. DCA uses large multiple sequence alignments to infer the interdependencies between residue positions in protein families and is robust at predicting protein contacts from sequence alone. Taking into account simple geometric considerations and strong experimental evidence for an antiparallel homodimer, we are able to parse the inter-and intra-monomeric contacts predicted by DCA. These contacts are used to bias a conformational search performed by a custom Rosetta fold-and-dock protocol. Final refined models are further relaxed with all-atom molecular dynamics simulations in an explicit membrane environment. Possible mechanisms for fluoride selectivity and permeation are discussed in light of the model. This study demonstrates the utility of DCA in the ab initio modeling of oligomers, suggests a novel sequence-based approach to identify dual-topology proteins, and provides a strong foundation for more directed experimental characterizations of the Fluc protein family.

F508del-CFTR, the most common disease-associated mutation in cystic fibrosis, may lose its responsiveness to the CFTR potentiator ivacaftor upon prolonged exposure to the newly developed CF drug Trikafta https://bit.ly/3A22MKQ Cite this article as: Yeh H-I, Hwang T-C. In vitro assessment of triple combination therapy for the most common disease-associated mutation in cystic fibrosis.