A5068157192- Ion channel regulation and function
- Cardiac electrophysiology and arrhythmias
- Lipid Membrane Structure and Behavior
- Neuroscience and Neural Engineering
- Neuroscience and Neuropharmacology Research
- Electrochemical Analysis and Applications
- Mass Spectrometry Techniques and Applications
- Photoreceptor and optogenetics research
- Immune Response and Inflammation
- Receptor Mechanisms and Signaling
- Nicotinic Acetylcholine Receptors Study
- Bacillus and Francisella bacterial research
- RNA and protein synthesis mechanisms
- Microfluidic and Capillary Electrophoresis Applications
- Advanced Memory and Neural Computing
- Bacterial Genetics and Biotechnology
- Toxin Mechanisms and Immunotoxins
- Advanced Fluorescence Microscopy Techniques
- Genetic Neurodegenerative Diseases
- Ion Channels and Receptors
- Nanopore and Nanochannel Transport Studies
- Insect Resistance and Genetics
- Analytical Chemistry and Sensors
- Crystal structures of chemical compounds
- Migraine and Headache Studies
Université de Montréal
2015-2024
Centre for Interdisciplinary Research in Rehabilitation
2023
Université Laval
2019
Laboratoire de Biologie Physico-Chimique des Protéines Membranaires
2011
Laboratoire de Mathématiques d'Orsay
2011
Czech Academy of Sciences, Institute of Physiology
2010
University of California, Los Angeles
2001-2006
California Institute of Technology
2004
California NanoSystems Institute
2004
Research Center Borstel - Leibniz Lung Center
1999-2001
Atomic-scale models on the gating mechanism of voltage-gated potassium channels (Kv) are based linear interpolations between static structures their initial and final state derived from crystallography molecular dynamics simulations, and, thus, lack dynamic structural information. The information intermediate states makes it difficult to associate with functional data obtained electrophysiology. Although voltage-clamp fluorometry fills this gap, is limited sites extracellularly accessible,...
Voltage-gated ion channels play a central role in the generation of action potentials nervous system. They are selective for one type - sodium, calcium, or potassium. composed pore that allows ions to pass through membrane and four peripheral voltage sensing domains respond changes potential. Upon depolarization, sensors voltage-gated potassium (Kv) undergo conformational driven by positive charges S4 segment aided pairwise electrostatic interactions with surrounding sensor....
Elucidating subunit stoichiometry of neurotransmitter receptors is preferably carried out in a mammalian expression system where the rules native protein assembly are strictly obeyed. Although successful Xenopus oocytes, single counting, manually counting photobleaching steps GFP-tagged subunits, has been hindered cells by high background fluorescence, poor control expression, and low GFP maturation efficiency. Here, we present fully automated single-molecule fluorescence method that...
Abstract LPS (endotoxins) activate cells of the human immune system, among which are monocytes and macrophages, to produce endogenous mediators. These regulate response, but may also cause severe harm leading septic shock. The activation monocytes/macrophages by is mediated a membrane-bound receptor, mCD14. As mCD14 lacks transmembrane domain, further protein required for signal transducing step cell interior. Here we show, using excised outside-out membrane patches, that high-conductance...
The closed KcsA channel structure revealed a crossing of the cytosolic ends transmembrane helices blocking permeation pathway. It is generally agreed that during opening this helical bundle has to widen in order enable access inner cavity. Here, we address question whether gate sufficient for ion conduction, or if second gate, located elsewhere, may interrupt flow. We used fluorescence lifetime measurements on channels labeled with tetramethylrhodamine at residues C-terminal end TM2 report...
Voltage-gated ion channels are controlled by the membrane potential, which is sensed peripheral, positively charged voltage sensors. The movement of residues in sensor may be detected as gating currents. In Shaker K(+) channels, currents asymmetric; although on-gating fast, off-gating contain a slow component. This component caused stabilization activated state and has been suggested to linked permeation or C-type inactivation. molecular determinants responsible for stabilization, however,...
The voltage sensors of voltage-gated ion channels undergo a conformational change upon depolarization the membrane that leads to pore opening. This can be measured as gating currents and is thought transferred domain via an annealing covalent link between sensor (S4-S5 linker) C terminus (S6). Upon prolonged depolarizations, dependence charge movement shifts more hyperpolarized potentials. mode shift had been linked C-type inactivation but has recently suggested caused by relaxation itself....
Significance Excitability in heart and nervous system is based on sensing propagation of the membrane potential by voltage-gated ion channels. Despite increasing availability high-resolution structures channels, key questions about their dynamics remain elusive. Here we followed movements gating machinery cytosolic surface Shaker K V channel introducing a fluorescent noncanonical amino acid at different positions along linker between voltage sensor pore. We can thus map movement each...
The structure and long-time dynamics of suspended lipid bilayers made 1-stearoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (SOPE) in the gel phase was interrogated using electrical measurements co-recorded with second harmonic generation (SHG) micrographs. SHG microscopy shown to be an efficient method for distinguishing between regions bilayer annulus as well probing structural dynamical variations within a single bilayer. Micromachined silicon chips two types plastic partitions, delrin...
Domains in macromolecular complexes are often considered structurally and functionally conserved while energetically coupled to each other. In the modular voltage-gated ion channels central ion-conducting pore is surrounded by four voltage sensing domains (VSDs). Here, energetic coupling mediated interactions between S4-S5 linker, covalently linking domains, proximal C-terminus. order characterize intrinsic gating of domain absence domain, Shaker Kv channel was truncated after fourth...
Significance Voltage-gated potassium (Kv) channels play a key role in cellular electrical excitability. While various Kv subunits assemble to homotetrameric functional channels, the silent subfamilies KvS exclusively form heterotetramers with Kv2 and thus regulate their biophysical properties tissue-specific way. Despite vast research, aspects of heterotetrameric architecture remain controversial, including stoichiometry which can assemble. We used concatemers single subunit counting...
The prokaryotic KcsA channel is gated at the helical bundle crossing by intracellular protons and inactivates extracellular selectivity filter. C-terminal transmembrane helix has to undergo a conformational change for potassium ions access central cavity. Whereas partial opening of tetrameric suggested be responsible subconductance levels ion channels, including KcsA, cooperative 4 subunits postulated as final step. In this study, we used single-channel fluorescence spectroscopy directly...
Pore-forming toxins constitute a class of potent virulence factors that attack their host membrane in two- or three-step mechanism. After binding to the membrane, often aided by specific receptors, they form pores membrane. Pore formation either unfolds cytolytic activity itself provides pathway introduce enzymes into cells act upon intracellular proteins. The elucidation pore-forming mechanism many these represents major research challenge. As refold after entering structure is unknown, and...
Abstract With the rapid development of a continuously growing selection unnatural amino acids (UAAs), UAA insertion becomes increasingly popular for investigating proteins. However, it can prove problematic to ensure homogeneity expressed proteins, when is compromised by “leak expression”. Here, we show that leak expression may be mediated reinitiation and result in unwanted proteins stop codons are mutated into N-terminus We demonstrate up 25% occurs through Shaker-Kv channel located within...