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Ceccarelli M, Milenkovic S, Bodrenko IV. The Effect of Lipopolysaccharides on the Electrostatic Properties of Gram-Negative General Porins from Enterobacteriaceae. Chemphyschem 2024:e202400147. [PMID: 38625051 DOI: 10.1002/cphc.202400147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 04/15/2024] [Accepted: 04/16/2024] [Indexed: 04/17/2024]
Abstract
We investigated, by using all-atom molecular dynamics simulations, the effect of the outer membrane of Gram-negative bacteria, composed in the outer leaflet by polar/charged lipopolysaccharides (LPS), on the electrostatic properties of general porins from the Enterobacteriaceae family. General porins constitute the main path for the facilitated diffusion of polar antibiotics through the outer membrane. As model system we selected OmpK36 from Klebsiella pneumoniae, the ortholog of OmpC from Escherichia coli. This species presents high variability of amino acid composition of porins, with the effect to increase its resistance to the penetration of antibiotics. The various properties we analyzed seem to indicate that LPS acts as an independent layer without affecting the internal electrostatic properties of OmpK36. The only apparent effect on the microsecond time scale we sampled is the appearance of calcium ions, when present at moderate concentration in solution, inside the pore. However, we noticed increased fluctuations of the polarization density and only minor changes on its average value.
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Affiliation(s)
- Matteo Ceccarelli
- Department of Physics, University of Cagliari, Cittadella Universitaria, 09042, Monserrato, IT
| | - Stefan Milenkovic
- Department of Physics, University of Cagliari, Cittadella Universitaria, 09042, Monserrato, IT
| | - Igor V Bodrenko
- Istituto Nanoscienze, CNR, piazza San Silvestro 12, 56127, Pisa, Italy
- Lab NEST, Scuola Normale Superiore, piazza San Silvestro 12, 56127, Pisa, Italy
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Farci D, Milenkovic S, Iesu L, Tanas M, Ceccarelli M, Piano D. Structural characterization and functional insights into the type II secretion system of the poly-extremophile Deinococcus radiodurans. J Biol Chem 2024; 300:105537. [PMID: 38072042 PMCID: PMC10828601 DOI: 10.1016/j.jbc.2023.105537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 11/07/2023] [Accepted: 11/28/2023] [Indexed: 01/21/2024] Open
Abstract
The extremophile bacterium D. radiodurans boasts a distinctive cell envelope characterized by the regular arrangement of three protein complexes. Among these, the Type II Secretion System (T2SS) stands out as a pivotal structural component. We used cryo-electron microscopy to reveal unique features, such as an unconventional protein belt (DR_1364) around the main secretin (GspD), and a cap (DR_0940) found to be a separated subunit rather than integrated with GspD. Furthermore, a novel region at the N-terminus of the GspD constitutes an additional second gate, supplementing the one typically found in the outer membrane region. This T2SS was found to contribute to envelope integrity, while also playing a role in nucleic acid and nutrient trafficking. Studies on intact cell envelopes show a consistent T2SS structure repetition, highlighting its significance within the cellular framework.
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Affiliation(s)
- Domenica Farci
- Department of Plant Physiology, Warsaw University of Life Sciences - SGGW, Warsaw, Poland; Department of Life and Environmental Sciences, Università degli Studi di Cagliari, Cagliari, Italy; R&D Department, ReGenFix Laboratories, Sardara, Italy.
| | - Stefan Milenkovic
- Department of Physics and IOM/CNR, Università degli Studi di Cagliari, Monserrato, Italy
| | - Luca Iesu
- Department of Life and Environmental Sciences, Università degli Studi di Cagliari, Cagliari, Italy
| | - Marta Tanas
- Department of Life and Environmental Sciences, Università degli Studi di Cagliari, Cagliari, Italy
| | - Matteo Ceccarelli
- Department of Physics and IOM/CNR, Università degli Studi di Cagliari, Monserrato, Italy
| | - Dario Piano
- Department of Plant Physiology, Warsaw University of Life Sciences - SGGW, Warsaw, Poland; Department of Life and Environmental Sciences, Università degli Studi di Cagliari, Cagliari, Italy; R&D Department, ReGenFix Laboratories, Sardara, Italy.
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Liu C, Xue L, Song C. Calcium binding and permeation in TRPV channels: Insights from molecular dynamics simulations. J Gen Physiol 2023; 155:e202213261. [PMID: 37728593 PMCID: PMC10510737 DOI: 10.1085/jgp.202213261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 05/21/2023] [Accepted: 09/06/2023] [Indexed: 09/21/2023] Open
Abstract
Some calcium channels selectively permeate Ca2+, despite the high concentration of monovalent ions in the surrounding environment, which is essential for many physiological processes. Without atomistic and dynamical ion permeation details, the underlying mechanism of Ca2+ selectivity has long been an intensively studied, yet controversial, topic. This study takes advantage of the homologous Ca2+-selective TRPV6 and non-selective TRPV1 and utilizes the recently solved open-state structures and a newly developed multisite calcium model to investigate the ion binding and permeation features in TRPV channels by molecular dynamics simulations. Our results revealed that the open-state TRPV6 and TRPV1 show distinct ion binding patterns in the selectivity filter, which lead to different ion permeation features. Two Ca2+ ions simultaneously bind to the selectivity filter of TRPV6 compared with only one Ca2+ in the case of TRPV1. Multiple Ca2+ binding at the selectivity filter of TRPV6 permeated in a concerted manner, which could efficiently block the permeation of Na+. Cations of various valences differentiate between the binding sites at the entrance of the selectivity filter in TRPV6. Ca2+ preferentially binds to the central site with a higher probability of permeation, repelling Na+ to a peripheral site. Therefore, we believe that ion binding competition at the selectivity filter of calcium channels, including the binding strength and number of binding sites, determines Ca2+ selectivity under physiological conditions.
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Affiliation(s)
- Chunhong Liu
- Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Lingfeng Xue
- Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Chen Song
- Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
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Medeiros-Silva J, Dregni AJ, Somberg NH, Duan P, Hong M. Atomic structure of the open SARS-CoV-2 E viroporin. SCIENCE ADVANCES 2023; 9:eadi9007. [PMID: 37831764 PMCID: PMC10575589 DOI: 10.1126/sciadv.adi9007] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 09/08/2023] [Indexed: 10/15/2023]
Abstract
The envelope (E) protein of the SARS-CoV-2 virus forms cation-conducting channels in the endoplasmic reticulum Golgi intermediate compartment (ERGIC) of infected cells. The calcium channel activity of E is associated with the inflammatory responses of COVID-19. Using solid-state NMR (ssNMR) spectroscopy, we have determined the open-state structure of E's transmembrane domain (ETM) in lipid bilayers. Compared to the closed state, open ETM has an expansive water-filled amino-terminal chamber capped by key glutamate and threonine residues, a loose phenylalanine aromatic belt in the middle, and a constricted polar carboxyl-terminal pore filled with an arginine and a threonine residue. This structure gives insights into how protons and calcium ions are selected by ETM and how they permeate across the hydrophobic gate of this viroporin.
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Affiliation(s)
| | - Aurelio J. Dregni
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | | | - Pu Duan
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Zhang J, Song D, Schackert FK, Li J, Xiang S, Tian C, Gong W, Carloni P, Alfonso-Prieto M, Shi C. Fluoride permeation mechanism of the Fluc channel in liposomes revealed by solid-state NMR. SCIENCE ADVANCES 2023; 9:eadg9709. [PMID: 37611110 PMCID: PMC10446490 DOI: 10.1126/sciadv.adg9709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 07/21/2023] [Indexed: 08/25/2023]
Abstract
Solid-state nuclear magnetic resonance (ssNMR) methods can probe the motions of membrane proteins in liposomes at the atomic level and propel the understanding of biomolecular processes for which static structures cannot provide a satisfactory description. In this work, we report our study on the fluoride channel Fluc-Ec1 in phospholipid bilayers based on ssNMR and molecular dynamics simulations. Previously unidentified fluoride binding sites in the aqueous vestibules were experimentally verified by 19F-detected ssNMR. One of the two fluoride binding sites in the polar track was identified as a water molecule by 1H-detected ssNMR. Meanwhile, a dynamic hotspot at loop 1 was observed by comparing the spectra of wild-type Fluc-Ec1 in variant buffer conditions or with its mutants. Therefore, we propose that fluoride conduction in the Fluc channel occurs via a "water-mediated knock-on" permeation mechanism and that loop 1 is a key molecular determinant for channel gating.
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Affiliation(s)
- Jin Zhang
- Department of Neurosurgery, The First Affiliated Hospital of USTC, Center for BioAnalytical Chemistry, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, University of Science and Technology of China, 230027 Hefei, P. R. China
| | - Dan Song
- Department of Neurosurgery, The First Affiliated Hospital of USTC, Center for BioAnalytical Chemistry, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, University of Science and Technology of China, 230027 Hefei, P. R. China
| | - Florian Karl Schackert
- Institute for Advanced Simulations (IAS-5) and Institute of Neuroscience and Medicine (INM-9), Computational Biomedicine, Forschungszentrum Jülich, 52428 Jülich, Germany
- Department of Physics, RWTH Aachen University, 52074 Aachen, Germany
| | - Juan Li
- Department of Neurosurgery, The First Affiliated Hospital of USTC, Center for BioAnalytical Chemistry, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, University of Science and Technology of China, 230027 Hefei, P. R. China
| | - Shengqi Xiang
- Department of Neurosurgery, The First Affiliated Hospital of USTC, Center for BioAnalytical Chemistry, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, University of Science and Technology of China, 230027 Hefei, P. R. China
| | - Changlin Tian
- Department of Neurosurgery, The First Affiliated Hospital of USTC, Center for BioAnalytical Chemistry, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, University of Science and Technology of China, 230027 Hefei, P. R. China
| | - Weimin Gong
- Department of Neurosurgery, The First Affiliated Hospital of USTC, Center for BioAnalytical Chemistry, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, University of Science and Technology of China, 230027 Hefei, P. R. China
| | - Paolo Carloni
- Institute for Advanced Simulations (IAS-5) and Institute of Neuroscience and Medicine (INM-9), Computational Biomedicine, Forschungszentrum Jülich, 52428 Jülich, Germany
- Department of Physics, RWTH Aachen University, 52074 Aachen, Germany
| | - Mercedes Alfonso-Prieto
- Institute for Advanced Simulations (IAS-5) and Institute of Neuroscience and Medicine (INM-9), Computational Biomedicine, Forschungszentrum Jülich, 52428 Jülich, Germany
| | - Chaowei Shi
- Department of Neurosurgery, The First Affiliated Hospital of USTC, Center for BioAnalytical Chemistry, Hefei National Research Center for Interdisciplinary Sciences at the Microscale, University of Science and Technology of China, 230027 Hefei, P. R. China
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