@article {2019|2076, title = {Glutathionylation primes soluble glyceraldehyde-3-phosphate dehydrogenase for late collapse into insoluble aggregates.}, journal = {Proc Natl Acad Sci U S A}, volume = {116}, year = {2019}, month = {2019 12 17}, pages = {26057-26065}, abstract = {

Protein aggregation is a complex physiological process, primarily determined by stress-related factors revealing the hidden aggregation propensity of proteins that otherwise are fully soluble. Here we report a mechanism by which glycolytic glyceraldehyde-3-phosphate dehydrogenase of (AtGAPC1) is primed to form insoluble aggregates by the glutathionylation of its catalytic cysteine (Cys149). Following a lag phase, glutathionylated AtGAPC1 initiates a self-aggregation process resulting in the formation of branched chains of globular particles made of partially misfolded and totally inactive proteins. GSH molecules within AtGAPC1 active sites are suggested to provide the initial destabilizing signal. The following removal of glutathione by the formation of an intramolecular disulfide bond between Cys149 and Cys153 reinforces the aggregation process. Physiological reductases, thioredoxins and glutaredoxins, could not dissolve AtGAPC1 aggregates but could efficiently contrast their growth. Besides acting as a protective mechanism against overoxidation, S-glutathionylation of AtGAPC1 triggers an unexpected aggregation pathway with completely different and still unexplored physiological implications.

}, issn = {1091-6490}, doi = {10.1073/pnas.1914484116}, author = {Zaffagnini, Mirko and Marchand, Christophe H and Malferrari, Marco and Murail, Samuel and Bonacchi, Sara and Genovese, Damiano and Montalti, Marco and Venturoli, Giovanni and Falini, Giuseppe and Marc Baaden and Lemaire, St{\'e}phane D and Fermani, Simona and Trost, Paolo} } @inbook {2018|2085, title = {Applications to water transport systems: general discussion.}, booktitle = {Faraday Discuss}, volume = {209}, year = {2018}, month = {2018 09 28}, pages = {389-414}, issn = {1364-5498}, doi = {10.1039/c8fd90022a}, author = {Marc Baaden and Barboiu, Mihail and Borthakur, Manash Pratim and Chen, Chun-Long and Coalson, Rob and Davis, Jeffery and Freger, Viatcheslav and Gong, Bing and H{\'e}lix-Nielsen, Claus and Hickey, Robert and Hinds, Bruce and Hirunpinyopas, Wisit and Horner, Andreas and Hou, Jun-Li and Hummer, Gerhard and Iamprasertkun, Pawin and Kazushi, Kinbara and Kumar, Manish and Legrand, Yves-Marie and Lokesh, Mahesh and Mi, Baoxia and Mitra, Sushanta and Murail, Samuel and Noy, Aleksandr and Nunes, Suzana and Pohl, Peter and Song, Qilei and Song, Woochul and T{\"o}rnroth-Horsefield, Susanna and Vashisth, Harish} } @inbook {2018|2082, title = {Biomimetic water channels: general discussion.}, booktitle = {Faraday Discuss}, volume = {209}, year = {2018}, month = {2018 09 28}, pages = {205-229}, issn = {1364-5498}, doi = {10.1039/c8fd90020e}, author = {Marc Baaden and Barboiu, Mihail and Bill, Roslyn M and Chen, Chun-Long and Davis, Jeffery and Di Vincenzo, Maria and Freger, Viatcheslav and Fr{\"o}ba, Michael and Gale, Philip A and Gong, Bing and H{\'e}lix-Nielsen, Claus and Hickey, Robert and Hinds, Bruce and Hou, Jun-Li and Hummer, Gerhard and Kumar, Manish and Legrand, Yves-Marie and Lokesh, Mahesh and Mi, Baoxia and Murail, Samuel and Pohl, Peter and Sansom, Mark and Song, Qilei and Song, Woochul and T{\"o}rnroth-Horsefield, Susanna and Vashisth, Harish and V{\"o}gele, Martin} } @inbook {2018|2084, title = {The modelling and enhancement of water hydrodynamics: general discussion.}, booktitle = {Faraday Discuss}, volume = {209}, year = {2018}, month = {2018 09 28}, pages = {273-285}, issn = {1364-5498}, doi = {10.1039/c8fd90021c}, author = {Marc Baaden and Borthakur, Manash Pratim and Casanova, Serena and Coalson, Rob and Freger, Viatcheslav and Gonzalez, Miguel and G{\'o}ra, Artur and Hinds, Bruce and Hirunpinyopas, Wisit and Hummer, Gerhard and Kumar, Manish and Lynch, Charlotte and Murail, Samuel and Noy, Aleksandr and Sansom, Mark and Song, Qilei and Vashisth, Harish and V{\"o}gele, Martin} } @article {2018|2092, title = {Oriented chiral water wires in artificial transmembrane channels.}, journal = {Sci Adv}, volume = {4}, year = {2018}, month = {2018 03}, pages = {eaao5603}, abstract = {

Aquaporins (AQPs) feature highly selective water transport through cell membranes, where the dipolar orientation of structured water wires spanning the AQP pore is of considerable importance for the selective translocation of water over ions. We recently discovered that water permeability through artificial water channels formed by stacked imidazole I-quartet superstructures increases when the channel water molecules are highly organized. Correlating water structure with molecular transport is essential for understanding the underlying mechanisms of (fast) water translocation and channel selectivity. Chirality adds another factor enabling unique dipolar oriented water structures. We show that water molecules exhibit a dipolar oriented wire structure within chiral I-quartet water channels both in the solid state and embedded in supported lipid bilayer membranes (SLBs). X-ray single-crystal structures show that crystallographic water wires exhibit dipolar orientation, which is unique for chiral I-quartets. The integration of I-quartets into SLBs was monitored with a quartz crystal microbalance with dissipation, quantizing the amount of channel water molecules. Nonlinear sum-frequency generation vibrational spectroscopy demonstrates the first experimental observation of dipolar oriented water structures within artificial water channels inserted in bilayer membranes. Confirmation of the ordered confined water is obtained via molecular simulations, which provide quantitative measures of hydrogen bond strength, connectivity, and the stability of their dipolar alignment in a membrane environment. Together, uncovering the interplay between the dipolar aligned water structure and water transport through the self-assembled I-quartets is critical to understanding the behavior of natural membrane channels and will accelerate the systematic discovery for developing artificial water channels for water desalting.

}, issn = {2375-2548}, doi = {10.1126/sciadv.aao5603}, author = {Kocsis, Istvan and Sorci, Mirco and Vanselous, Heather and Murail, Samuel and Sanders, Stephanie E and Licsandru, Erol and Legrand, Yves-Marie and van der Lee, Arie and Marc Baaden and Petersen, Poul B and Belfort, Georges and Barboiu, Mihail} } @article {2018|2090, title = {Water permeation across artificial I-quartet membrane channels: from structure to disorder.}, journal = {Faraday Discuss}, volume = {209}, year = {2018}, month = {2018 09 28}, pages = {125-148}, abstract = {

Artificial water channels (AWCs) have been designed for water transport across membranes with the aim to mimic the high water permeability observed for biological systems such as aquaporins (\∼108-109 water molecules per s per channel), as well as their selectivity to reject ion permeation at the same time. Recent works on designed self-assembling alkylureido-ethylimidazole compounds forming imidazole-quartet channels (I-quartets), have shown both high water permeability and total ionic-rejection. I-quartets are thus promising candidates for further development of AWCs. However, the molecular mechanism of water permeation as well as I-quartet organization and stability in a membrane environment need to be fully understood to guide their optimal design. Here, we use a wide range of all-atom molecular dynamics (MD) simulations and their analysis to understand the structure/activity relationships of the I-quartet channels. Four different types with varying alkyl chain length or chirality have been studied in a complex fully hydrated lipid bilayer environment at both microsecond and nanosecond scale. Microsecond simulations show two distinct behaviors; (i) two out of four systems maintain chiral dipolar oriented water wires, but also undergo a strong reorganization of the crystal shape, (ii) the two other I-quartet channels completely lose the initial organization, nonetheless keeping a water transport activity. Short MD simulations with higher time resolution were conducted to characterize the dynamic properties of water molecules in these model channels and provided a detailed hypothesis on the molecular mechanism of water permeation. The ordered confined water was characterized with quantitative measures of hydrogen-bond life-time and single particle dynamics, showing variability among I-quartet channels. We will further discuss the underlying assumptions, currently based on self-aggregation simulations and crystal patches embedded in lipid bilayer simulations and attempt to describe possible alternative approaches to computationally capture the water permeation mechanism and the self-assembly process of these AWCs.

}, issn = {1364-5498}, doi = {10.1039/c8fd00046h}, author = {Murail, Samuel and Vasiliu, Tudor and Neamtu, Andrei and Barboiu, Mihail and Sterpone, Fabio and Marc Baaden} } @article {2017|2096, title = {String method solution of the gating pathways for a pentameric ligand-gated ion channel.}, journal = {Proc Natl Acad Sci U S A}, volume = {114}, year = {2017}, month = {2017 05 23}, pages = {E4158-E4167}, abstract = {

Pentameric ligand-gated ion channels control synaptic neurotransmission by converting chemical signals into electrical signals. Agonist binding leads to rapid signal transduction via an allosteric mechanism, where global protein conformational changes open a pore across the nerve cell membrane. We use all-atom molecular dynamics with a swarm-based string method to solve for the minimum free-energy gating pathways of the proton-activated bacterial GLIC channel. We describe stable wetted/open and dewetted/closed states, and uncover conformational changes in the agonist-binding extracellular domain, ion-conducting transmembrane domain, and gating interface that control communication between these domains. Transition analysis is used to compute free-energy surfaces that suggest allosteric pathways; stabilization with pH; and intermediates, including states that facilitate channel closing in the presence of an agonist. We describe a switching mechanism that senses proton binding by marked reorganization of subunit interface, altering the packing of β-sheets to induce changes that lead to asynchronous pore-lining M2 helix movements. These results provide molecular details of GLIC gating and insight into the allosteric mechanisms for the superfamily of pentameric ligand-gated channels.

}, keywords = {Computer Simulation, Ligand-Gated Ion Channels, Models, Biological, Models, Chemical}, issn = {1091-6490}, doi = {10.1073/pnas.1617567114}, author = {Lev, Bogdan and Murail, Samuel and Poitevin, Fr{\'e}d{\'e}ric and Cromer, Brett A and Marc Baaden and Delarue, Marc and Allen, Toby W} }