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Saha I, Chakraborty S, Agarwal S, Mukherjee P, Ghosh B, Dasgupta J. Mechanistic insights of ABC importer HutCD involved in heme internalization by Vibrio cholerae. Sci Rep 2022; 12:7152. [PMID: 35504999 PMCID: PMC9065009 DOI: 10.1038/s41598-022-11213-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Accepted: 03/24/2022] [Indexed: 11/10/2022] Open
Abstract
Heme internalization by pathogenic bacteria inside a human host to accomplish the requirement of iron for important cellular processes is of paramount importance. Despite this, the mechanism of heme import by the ATP-binding-cassette (ABC) transporter HutCD in Vibrio cholerae remains unexplored. We have performed biochemical studies on ATPase HutD and its mutants, along with molecular modelling, docking and unbiased all-atom MD simulations on lipid-solvated models of permease-ATPase complex HutCD. The results demonstrated mechanisms of ATP binding/hydrolysis and trapped transient and global conformational changes in HutCD, necessary for heme internalization. ATPase HutD forms a dimer, independent of the permease HutC. Each HutD monomer canonically binds ATP in a 1:1 stoichiometry. MD simulations demonstrated that a rotational motion of HutC dimer occurs synchronously with the inter-dimeric D-loop interactions of HutDs. F151 of TM4–TM5 loop of HutC, packs with ATP and Y15 of HutD, initiating ‘cytoplasmic gate opening’ which mimics an ‘outward-facing’ to ‘inward-facing’ conformational switching upon ATP hydrolysis. The simulation on ‘inward-facing’ HutCD culminates to an ‘occluded’ state. The simulation on heme-docked HutCD indicated that the event of heme release occurs in ATP-free ‘inward-facing’ state. Gradual conformational changes of the TM5 helices of HutC towards the ‘occluded’ state facilitate ejection of heme.
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Affiliation(s)
- Indrila Saha
- Department of Biotechnology, St. Xavier's College (Autonomous), 30, Mother Teresa Sarani, Kolkata, 700016, India
| | - Shrestha Chakraborty
- Department of Biotechnology, St. Xavier's College (Autonomous), 30, Mother Teresa Sarani, Kolkata, 700016, India
| | - Shubhangi Agarwal
- Department of Biotechnology, St. Xavier's College (Autonomous), 30, Mother Teresa Sarani, Kolkata, 700016, India.,Weill Cornell Medicine, Department of Anesthesiology, 1300 York Ave, New York, NY, 10065, USA
| | - Peeali Mukherjee
- Department of Biotechnology, St. Xavier's College (Autonomous), 30, Mother Teresa Sarani, Kolkata, 700016, India
| | - Biplab Ghosh
- Macromolecular Crystallography Section, Beamline Development & Application Section, Bhabha Atomic Research Center, Trombay, Mumbai, 400085, India.
| | - Jhimli Dasgupta
- Department of Biotechnology, St. Xavier's College (Autonomous), 30, Mother Teresa Sarani, Kolkata, 700016, India.
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Extracellular haem utilization by the opportunistic pathogen Pseudomonas aeruginosa and its role in virulence and pathogenesis. Adv Microb Physiol 2021; 79:89-132. [PMID: 34836613 DOI: 10.1016/bs.ampbs.2021.07.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Iron is an essential micronutrient for all bacteria but presents a significant challenge given its limited bioavailability. Furthermore, iron's toxicity combined with the need to maintain iron levels within a narrow physiological range requires integrated systems to sense, regulate and transport a variety of iron complexes. Most bacteria encode systems to chelate and transport ferric iron (Fe3+) via siderophore receptor mediated uptake or via cytoplasmic energy dependent transport systems. Pathogenic bacteria have further lowered the barrier to iron acquisition by employing systems to utilize haem as a source of iron. Haem, a lipophilic and toxic molecule, presents a significant challenge for transport into the cell. As such pathogenic bacteria have evolved sophisticated cell surface signaling (CSS) and transport systems to sense and obtain haem from the host. Once internalized haem is cleaved by both oxidative and non-oxidative mechanisms to release iron. Herein we summarize our current understanding of the mechanism of haem sensing, uptake and utilization in Pseudomonas aeruginosa, its role in pathogenesis and virulence, and the potential of these systems as antimicrobial targets.
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Structural and energetic analysis of metastable intermediate states in the E1P-E2P transition of Ca 2+-ATPase. Proc Natl Acad Sci U S A 2021; 118:2105507118. [PMID: 34593638 PMCID: PMC8501872 DOI: 10.1073/pnas.2105507118] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/23/2021] [Indexed: 01/05/2023] Open
Abstract
Ion pumps (or P-type ATPases) are membrane proteins, which transport ions through biological membranes against a concentration gradient, a function essential for many biological processes, such as muscle contraction, neurotransmission, and metabolism. Molecular mechanisms underlying active ion transport by ion pumps have been investigated by biochemical experiments and high-resolution structure analyses. Here, the transition of sarcoplasmic reticulum Ca2+-ATPase upon dissociation of Ca2+ is investigated using atomistic molecular dynamics simulations. We find intermediate structures along the pathway are stabilized by transient interactions between A- and P-domains as well as lipid molecules in the transmembrane helices. Sarcoplasmic reticulum (SR) Ca2+-ATPase transports two Ca2+ ions from the cytoplasm to the SR lumen against a large concentration gradient. X-ray crystallography has revealed the atomic structures of the protein before and after the dissociation of Ca2+, while biochemical studies have suggested the existence of intermediate states in the transition between E1P⋅ADP⋅2Ca2+ and E2P. Here, we explore the pathway and free energy profile of the transition using atomistic molecular dynamics simulations with the mean-force string method and umbrella sampling. The simulations suggest that a series of structural changes accompany the ordered dissociation of ADP, the A-domain rotation, and the rearrangement of the transmembrane (TM) helices. The luminal gate then opens to release Ca2+ ions toward the SR lumen. Intermediate structures on the pathway are stabilized by transient sidechain interactions between the A- and P-domains. Lipid molecules between TM helices play a key role in the stabilization. Free energy profiles of the transition assuming different protonation states suggest rapid exchanges between Ca2+ ions and protons when the Ca2+ ions are released toward the SR lumen.
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He X, Li M, Yu D, Wang B, Zhao D, Rong C, Liu S. Conformational changes for porphyrinoid derivatives: an information-theoretic approach study. Theor Chem Acc 2021. [DOI: 10.1007/s00214-021-02824-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Shinobu A, Kobayashi C, Matsunaga Y, Sugita Y. Coarse-Grained Modeling of Multiple Pathways in Conformational Transitions of Multi-Domain Proteins. J Chem Inf Model 2021; 61:2427-2443. [PMID: 33956432 DOI: 10.1021/acs.jcim.1c00286] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Large-scale conformational transitions in multi-domain proteins are often essential for their functions. To investigate the transitions, it is necessary to explore multiple potential pathways, which involve different intermediate structures. Here, we present a multi-basin (MB) coarse-grained (CG) structure-based Go̅ model for describing transitions in proteins with more than two moving domains. This model is an extension of our dual-basin Go̅ model in which system-dependent parameters are determined systematically using the multistate Bennett acceptance ratio method. In the MB Go̅ model for multi-domain proteins, we assume that intermediate structures may have partial inter-domain native contacts. This approach allows us to search multiple transition pathways that involve distinct intermediate structures using the CG molecular dynamics (MD) simulations. We apply this scheme to an enzyme, adenylate kinase (AdK), which has three major domains and can move along two different pathways. Using the optimized mixing parameters for each pathway, AdK shows frequent transitions between the Open, Closed, and the intermediate basins and samples a wide variety of conformations within each basin. The explored multiple transition pathways could be compared with experimental data and examined in more detail by atomistic MD simulations.
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Affiliation(s)
- Ai Shinobu
- Laboratory for Biomolecular Function Simulation, RIKEN Center for Biosystems Dynamics Research, Kobe, Hyogo 650-0047, Japan
| | - Chigusa Kobayashi
- Computational Biophysics Research Team, RIKEN Center for Computational Science, Kobe, Hyogo 650-0047, Japan
| | - Yasuhiro Matsunaga
- Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan
| | - Yuji Sugita
- Laboratory for Biomolecular Function Simulation, RIKEN Center for Biosystems Dynamics Research, Kobe, Hyogo 650-0047, Japan.,Computational Biophysics Research Team, RIKEN Center for Computational Science, Kobe, Hyogo 650-0047, Japan.,Theoretical Molecular Science Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan
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Barth K, Rudolph M, Diederichs T, Prisner TF, Tampé R, Joseph B. Thermodynamic Basis for Conformational Coupling in an ATP-Binding Cassette Exporter. J Phys Chem Lett 2020; 11:7946-7953. [PMID: 32818376 DOI: 10.1021/acs.jpclett.0c01876] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
ATP-binding cassette (ABC) transporters constitute one of the largest protein superfamilies, and they mediate the transport of diverse substrates across the membrane. The molecular mechanism for transducing the energy from ATP binding and hydrolysis into the conformational changes remains elusive. Here, we determined the thermodynamics underlying the ATP-induced global conformational switching for the ABC exporter TmrAB using temperature-resolved pulsed electron-electron double resonance (PELDOR or DEER) spectroscopy. We show that a strong entropy-enthalpy compensation mechanism enables the closure of the nucleotide-binding domains (NBDs) over a wide temperature range. This is mechanically coupled with an outward opening of the transmembrane domains (TMDs) accompanied by an entropy gain. The conserved catalytic glutamate plays a key role in the overall energetics. Our results reveal the thermodynamic basis for the chemomechanical energy coupling in an ABC exporter and present a new strategy to explore the energetics of similar membrane protein complexes.
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Affiliation(s)
- Katja Barth
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 7, 60438 Frankfurt/Main, Germany
- Centre of Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue-Str. 9, 60438 Frankfurt/Main, Germany
| | - Michael Rudolph
- Centre of Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue-Str. 9, 60438 Frankfurt/Main, Germany
- Institute of Biophysics, Goethe University Frankfurt, Max-von-Laue-Str. 1, 60438 Frankfurt/Main, Germany
| | - Tim Diederichs
- Institute of Biochemistry, Biocenter, Goethe University Frankfurt, Max-von-Laue-Str. 9, 60438 Frankfurt/Main, Germany
| | - Thomas F Prisner
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 7, 60438 Frankfurt/Main, Germany
- Centre of Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue-Str. 9, 60438 Frankfurt/Main, Germany
| | - Robert Tampé
- Institute of Biochemistry, Biocenter, Goethe University Frankfurt, Max-von-Laue-Str. 9, 60438 Frankfurt/Main, Germany
| | - Benesh Joseph
- Centre of Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue-Str. 9, 60438 Frankfurt/Main, Germany
- Institute of Biophysics, Goethe University Frankfurt, Max-von-Laue-Str. 1, 60438 Frankfurt/Main, Germany
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