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1دورية أكاديمية
المؤلفون: Balasubramanian Chandramouli, Danilo Di Maio, Giordano Mancini, Vincenzo Barone, Giuseppe Brancato
المصدر: PLoS ONE, Vol 10, Iss 3, p e0120196 (2015)
الوصف: The mechanosensitive channel of large conductance (MscL) is a protein that responds to membrane tension by opening a transient pore during osmotic downshock. Due to its large pore size and functional reconstitution into lipid membranes, MscL has been proposed as a promising artificial nanovalve suitable for biotechnological applications. For example, site-specific mutations and tailored chemical modifications have shown how MscL channel gating can be triggered in the absence of tension by introducing charged residues at the hydrophobic pore level. Recently, engineered MscL proteins responsive to stimuli like pH or light have been reported. Inspired by experiments, we present a thorough computational study aiming at describing, with atomistic detail, the artificial gating mechanism and the molecular transport properties of a light-actuated bacterial MscL channel, in which a charge-induced gating mechanism has been enabled through the selective cleavage of photo-sensitive alkylating agents. Properties such as structural transitions, pore dimension, ion flux and selectivity have been carefully analyzed. Besides, the effects of charge on alternative sites of the channel with respect to those already reported have been addressed. Overall, our results provide useful molecular insights into the structural events accompanying the engineered MscL channel gating and the interplay of electrostatic effects, channel opening and permeation properties. In addition, we describe how the experimentally observed ionic current in a single-subunit charged MscL mutant is obtained through a hydrophobicity breaking mechanism involving an asymmetric inter-subunit motion.
وصف الملف: electronic resource
العلاقة: https://doaj.org/toc/1932-6203Test
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2دورية أكاديمية
المصدر: PLoS ONE, Vol 10, Iss 10, p e0140258 (2015)
الوصف: Pentameric ligand gated ion channels (pLGICs) are ionotropic receptors that mediate fast intercellular communications at synaptic level and include either cation selective (e.g., nAChR and 5-HT3) or anion selective (e.g., GlyR, GABAA and GluCl) membrane channels. Among others, 5-HT3 is one of the most studied members, since its first cloning back in 1991, and a large number of studies have successfully pinpointed protein residues critical for its activation and channel gating. In addition, 5-HT3 is also the target of a few pharmacological treatments due to the demonstrated benefits of its modulation in clinical trials. Nonetheless, a detailed molecular analysis of important protein features, such as the origin of its ion selectivity and the rather low conductance as compared to other channel homologues, has been unfeasible until the recent crystallization of the mouse 5-HT3A receptor. Here, we present extended molecular dynamics simulations and free energy calculations of the whole 5-HT3A protein with the aim of better understanding its ion transport properties, such as the pathways for ion permeation into the receptor body and the complex nature of the selectivity filter. Our investigation unravels previously unpredicted structural features of the 5-HT3A receptor, such as the existence of alternative intersubunit pathways for ion translocation at the interface between the extracellular and the transmembrane domains, in addition to the one along the channel main axis. Moreover, our study offers a molecular interpretation of the role played by an arginine triplet located in the intracellular domain on determining the characteristic low conductance of the 5-HT3A receptor, as evidenced in previous experiments. In view of these results, possible implications on other members of the superfamily are suggested.
وصف الملف: electronic resource
العلاقة: http://europepmc.org/articles/PMC4605793?pdf=renderTest; https://doaj.org/toc/1932-6203Test
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3
المساهمون: DI MAIO, Danilo, Chandramouli, Balasubramanian, Brancato, Giuseppe
المصدر: PLoS ONE
PLoS ONE, Vol 10, Iss 10, p e0140258 (2015)مصطلحات موضوعية: Models, Molecular, Protein Conformation, lcsh:Medicine, Mice, Protein structure, Animals, Ion, lcsh:Science, Glycine receptor, Ion transporter, Ions, Multidisciplinary, Animal, Chemistry, GABAA receptor, lcsh:R, Biological Transport, Light-gated ion channel, Transmembrane domain, Biochemistry, Mutation, Biophysics, Ligand-gated ion channel, lcsh:Q, Receptors, Serotonin, 5-HT3, Signal transduction, Signal Transduction, Research Article
الوصف: Pentameric ligand gated ion channels (pLGICs) are ionotropic receptors that mediate fast intercellular communications at synaptic level and include either cation selective (e.g., nAChR and 5-HT3) or anion selective (e.g., GlyR, GABAA and GluCl) membrane channels. Among others, 5-HT3 is one of the most studied members, since its first cloning back in 1991, and a large number of studies have successfully pinpointed protein residues critical for its activation and channel gating. In addition, 5-HT3 is also the target of a few pharmacological treatments due to the demonstrated benefits of its modulation in clinical trials. Nonetheless, a detailed molecular analysis of important protein features, such as the origin of its ion selectivity and the rather low conductance as compared to other channel homologues, has been unfeasible until the recent crystallization of the mouse 5-HT3A receptor. Here, we present extended molecular dynamics simulations and free energy calculations of the whole 5-HT3A protein with the aim of better understanding its ion transport properties, such as the pathways for ion permeation into the receptor body and the complex nature of the selectivity filter. Our investigation unravels previously unpredicted structural features of the 5-HT3A receptor, such as the existence of alternative intersubunit pathways for ion translocation at the interface between the extracellular and the transmembrane domains, in addition to the one along the channel main axis. Moreover, our study offers a molecular interpretation of the role played by an arginine triplet located in the intracellular domain on determining the characteristic low conductance of the 5-HT3A receptor, as evidenced in previous experiments. In view of these results, possible implications on other members of the superfamily are suggested.
الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::7f599a9171d0d9fb24a8a06b4b7e01deTest
https://doi.org/10.1371/journal.pone.0140258Test
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