1
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Soong TH, Hotze C, Khandelwal NK, Tomasiak TM. Structural Basis for Oxidized Glutathione Recognition by the Yeast Cadmium Factor 1. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.31.578287. [PMID: 38352558 PMCID: PMC10862839 DOI: 10.1101/2024.01.31.578287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/24/2024]
Abstract
Transporters from the ABCC family have an essential role in detoxifying electrophilic compounds including metals, drugs, and lipids, often through conjugation with glutathione complexes. The Yeast Cadmium Factor 1 (Ycf1) transports glutathione alone as well as glutathione conjugated to toxic heavy metals including Cd2+, Hg2+, and As3+. To understand the complicated selectivity and promiscuity of heavy metal substrate binding, we determined the cryo-EM structure of Ycf1 bound to the substrate, oxidized glutathione. We systematically tested binding determinants with cellular survival assays against cadmium to determine how the substrate site accommodates different-sized metal complexes. We identify a "flex-pocket" for substrate binding that binds glutathione complexes asymmetrically and flexes to accommodate different size complexes.
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Affiliation(s)
- Tik Hang Soong
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Clare Hotze
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Nitesh Kumar Khandelwal
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
- Department of Biochemistry and Physics, University of California San Francisco, San Francisco, CA 94158, USA
| | - Thomas M Tomasiak
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
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2
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Khandelwal NK, Tomasiak TM. Structural basis for autoinhibition by the dephosphorylated regulatory domain of Ycf1. Nat Commun 2024; 15:2389. [PMID: 38493146 PMCID: PMC10944535 DOI: 10.1038/s41467-024-46722-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 03/01/2024] [Indexed: 03/18/2024] Open
Abstract
Yeast Cadmium Factor 1 (Ycf1) sequesters glutathione and glutathione-heavy metal conjugates into yeast vacuoles as a cellular detoxification mechanism. Ycf1 belongs to the C subfamily of ATP Binding Cassette (ABC) transporters characterized by long flexible linkers, notably the regulatory domain (R-domain). R-domain phosphorylation is necessary for activity, whereas dephosphorylation induces autoinhibition through an undefined mechanism. Because of its transient and dynamic nature, no structure of the dephosphorylated Ycf1 exists, limiting understanding of this R-domain regulation. Here, we capture the dephosphorylated Ycf1 using cryo-EM and show that the unphosphorylated R-domain indeed forms an ordered structure with an unexpected hairpin topology bound within the Ycf1 substrate cavity. This architecture and binding mode resemble that of a viral peptide inhibitor of an ABC transporter and the secreted bacterial WXG peptide toxins. We further reveal the subset of phosphorylation sites within the hairpin turn that drive the reorganization of the R-domain conformation, suggesting a mechanism for Ycf1 activation by phosphorylation-dependent release of R-domain mediated autoinhibition.
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Affiliation(s)
- Nitesh Kumar Khandelwal
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, USA
- Department of Biochemistry and Biophysics, University of California - San Francisco, San Francisco, CA, 94158, USA
| | - Thomas M Tomasiak
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, USA.
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3
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Lyon SE, Wencker FDR, Fernando CM, Harris KA, Breaker RR. Disruption of the bacterial OLE RNP complex impairs growth on alternative carbon sources. PNAS NEXUS 2024; 3:pgae075. [PMID: 38415217 PMCID: PMC10898510 DOI: 10.1093/pnasnexus/pgae075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2023] [Accepted: 02/06/2024] [Indexed: 02/29/2024]
Abstract
Ornate, large, extremophilic (OLE) RNAs comprise a class of large noncoding RNAs in bacteria whose members form a membrane-associated ribonucleoprotein (RNP) complex. This complex facilitates cellular adaptation to diverse stresses such as exposure to cold, short-chain alcohols, and elevated Mg2+ concentrations. Here, we report additional phenotypes exhibited by Halalkalibacterium halodurans (formerly called Bacillus halodurans) strains lacking functional OLE RNP complexes. Genetic disruption of the complex causes restricted growth compared to wild-type cells when cultured in minimal media (MM) wherein glucose is replaced with alternative carbon/energy sources. Genetic suppressor selections conducted in glutamate MM yielded isolates that carry mutations in or near genes relevant to Mn2+ homeostasis (ykoY and mntB), phosphate homeostasis (phoR), and putative multidrug resistance (bmrCD). These functional links between OLE RNA, carbon/energy management, and other fundamental processes including protein secretion are consistent with the hypothesis that the OLE RNP complex is a major contributor to cellular adaptation to unfavorable growth conditions.
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Affiliation(s)
- Seth E Lyon
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Freya D R Wencker
- Howard Hughes Medical Institute, Yale University, New Haven, CT 06511, USA
| | - Chrishan M Fernando
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
| | - Kimberly A Harris
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511, USA
| | - Ronald R Breaker
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA
- Howard Hughes Medical Institute, Yale University, New Haven, CT 06511, USA
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511, USA
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4
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Tang Q, Sinclair M, Hasdemir HS, Stein RA, Karakas E, Tajkhorshid E, Mchaourab HS. Asymmetric conformations and lipid interactions shape the ATP-coupled cycle of a heterodimeric ABC transporter. Nat Commun 2023; 14:7184. [PMID: 37938578 PMCID: PMC10632425 DOI: 10.1038/s41467-023-42937-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 10/26/2023] [Indexed: 11/09/2023] Open
Abstract
Here we used cryo-electron microscopy (cryo-EM), double electron-electron resonance spectroscopy (DEER), and molecular dynamics (MD) simulations, to capture and characterize ATP- and substrate-bound inward-facing (IF) and occluded (OC) conformational states of the heterodimeric ATP binding cassette (ABC) multidrug exporter BmrCD in lipid nanodiscs. Supported by DEER analysis, the structures reveal that ATP-powered isomerization entails changes in the relative symmetry of the BmrC and BmrD subunits that propagates from the transmembrane domain to the nucleotide binding domain. The structures uncover asymmetric substrate and Mg2+ binding which we hypothesize are required for triggering ATP hydrolysis preferentially in one of the nucleotide-binding sites. MD simulations demonstrate that multiple lipid molecules differentially bind the IF versus the OC conformation thus establishing that lipid interactions modulate BmrCD energy landscape. Our findings are framed in a model that highlights the role of asymmetric conformations in the ATP-coupled transport with general implications to the mechanism of ABC transporters.
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Affiliation(s)
- Qingyu Tang
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37232, USA
| | - Matt Sinclair
- Theoretical and Computational Biophysics Group, NIH Resource for Macromolecular Modeling and Visualization, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Hale S Hasdemir
- Theoretical and Computational Biophysics Group, NIH Resource for Macromolecular Modeling and Visualization, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Richard A Stein
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37232, USA
| | - Erkan Karakas
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37232, USA
| | - Emad Tajkhorshid
- Theoretical and Computational Biophysics Group, NIH Resource for Macromolecular Modeling and Visualization, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Hassane S Mchaourab
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37232, USA.
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5
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Vitali V, Ackermann K, Hagelueken G, Bode BE. Spectroscopically Orthogonal Labelling to Disentangle Site-Specific Nitroxide Label Distributions. APPLIED MAGNETIC RESONANCE 2023; 55:187-205. [PMID: 38357007 PMCID: PMC10861635 DOI: 10.1007/s00723-023-01611-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 08/23/2023] [Accepted: 08/25/2023] [Indexed: 02/16/2024]
Abstract
Biomolecular applications of pulse dipolar electron paramagnetic resonance spectroscopy (PDS) are becoming increasingly valuable in structural biology. Site-directed spin labelling of proteins is routinely performed using nitroxides, with paramagnetic metal ions and other organic radicals gaining popularity as alternative spin centres. Spectroscopically orthogonal spin labelling using different types of labels potentially increases the information content available from a single sample. When analysing experimental distance distributions between two nitroxide spin labels, the site-specific rotamer information has been projected into the distance and is not readily available, and the contributions of individual labelling sites to the width of the distance distribution are not obvious from the PDS data. Here, we exploit the exquisite precision of labelling double-histidine (dHis) motifs with CuII chelate complexes. The contribution of this label to the distance distribution widths in model protein GB1 has been shown to be negligible. By combining a dHis CuII labelling site with cysteine-specific nitroxide labelling, we gather insights on the label rotamers at two distinct sites, comparing their contributions to distance distributions based on different in silico modelling approaches and structural models. From this study, it seems advisable to consider discrepancies between different in silico modelling approaches when selecting labelling sites for PDS studies. Supplementary Information The online version contains supplementary material available at 10.1007/s00723-023-01611-1.
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Affiliation(s)
- Valentina Vitali
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex, and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews, KY16 9ST Scotland
- Magnetic Resonance Center (CERM), University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Italy
- Department of Chemistry “Ugo Schiff”, University of Florence, Via Della Lastruccia 3, 50019 Sesto Fiorentino, Italy
| | - Katrin Ackermann
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex, and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews, KY16 9ST Scotland
| | - Gregor Hagelueken
- Institute of Structural Biology, Biomedical Center, University of Bonn, Venusberg-Campus 1, 53127 Bonn, Germany
| | - Bela E. Bode
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex, and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews, KY16 9ST Scotland
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6
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Rudolph M, Tampé R, Joseph B. Time-Resolved Mn 2+ -NO and NO-NO Distance Measurements Reveal That Catalytic Asymmetry Regulates Alternating Access in an ABC Transporter. Angew Chem Int Ed Engl 2023; 62:e202307091. [PMID: 37459565 DOI: 10.1002/anie.202307091] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 07/17/2023] [Indexed: 08/08/2023]
Abstract
ATP-binding cassette (ABC) transporters shuttle diverse substrates across biological membranes. Transport is often achieved through a transition between an inward-facing (IF) and an outward-facing (OF) conformation of the transmembrane domains (TMDs). Asymmetric nucleotide-binding sites (NBSs) are present among several ABC subfamilies and their functional role remains elusive. Here we addressed this question using concomitant NO-NO, Mn2+ -NO, and Mn2+ -Mn2+ pulsed electron-electron double-resonance spectroscopy of TmrAB in a time-resolved manner. This type-IV ABC transporter undergoes a reversible transition in the presence of ATP with a significantly faster forward transition. The impaired degenerate NBS stably binds Mn2+ -ATP, and Mn2+ is preferentially released at the active consensus NBS. ATP hydrolysis at the consensus NBS considerably accelerates the reverse transition. Both NBSs fully open during each conformational cycle and the degenerate NBS may regulate the kinetics of this process.
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Affiliation(s)
- Michael Rudolph
- Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
| | - Robert Tampé
- Institute of Biochemistry, Biocenter, Goethe University Frankfurt, Max-von-Laue-Str. 9, 60438, Frankfurt/Main, Germany
| | - Benesh Joseph
- Department of Physics, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany
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7
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Tang Q, Sinclair M, Hasdemir HS, Stein R, Karakas E, Tajkhorshid E, Mchaourab H. Asymmetric conformations and lipid interactions shape the ATP-coupled cycle of a heterodimeric ABC transporter. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.29.541986. [PMID: 37398337 PMCID: PMC10312460 DOI: 10.1101/2023.05.29.541986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
To illuminate the structural origin of catalytic asymmetry of heterodimeric ABC transporters and how it shapes the energetics of their conformational cycles, we used cryo-electron microscopy (cryo-EM), double electron-electron resonance spectroscopy (DEER), and molecular dynamics (MD) simulations, to capture and characterize conformational states of the heterodimeric ABC multidrug exporter BmrCD in lipid nanodiscs. In addition to multiple ATP- and substrate-bound inward-facing (IF) conformations, we obtained the structure of an occluded (OC) conformation wherein the unique extracellular domain (ECD) twists to partially open the extracellular gate. In conjunction with DEER analysis of the populations of these conformations, the structures reveal that ATP-powered isomerization entails changes in the relative symmetry of the BmrC and BmrD subunits that propagates from the transmembrane domain (TMD) to the nucleotide binding domain (NBD). The structures uncover asymmetric substrate and Mg 2+ binding which we hypothesize are required for triggering ATP hydrolysis preferentially in one of the nucleotide-binding sites. MD simulations demonstrated that multiple lipid molecules, identified from the cryo-EM density maps, differentially bind the IF versus the OC conformation thus modulating their relative stability. In addition to establishing how lipid interactions with BmrCD modulate the energy landscape, our findings are framed in a distinct transport model that highlights the role of asymmetric conformations in the ATP-coupled cycle with implications to the mechanism of ABC transporters in general.
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8
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Cordeiro MM, Filipe HAL, dos Santos P, Samelo J, Ramalho JPP, Loura LMS, Moreno MJ. Interaction of Hoechst 33342 with POPC Membranes at Different pH Values. Molecules 2023; 28:5640. [PMID: 37570608 PMCID: PMC10420284 DOI: 10.3390/molecules28155640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 07/18/2023] [Accepted: 07/21/2023] [Indexed: 08/13/2023] Open
Abstract
Hoechst 33342 (H33342) is a fluorescent probe that is commonly used to stain the DNA of living cells. To do so, it needs to interact with and permeate through cell membranes, despite its high overall charge at physiological pH values. In this work, we address the effect of pH in the association of H33342 with lipid bilayers using a combined experimental and computational approach. The partition of H33342 to 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) lipid membranes was experimentally quantified using fluorescence spectroscopy and isothermal titration calorimetry (ITC) measurements. Quantum chemical calculations were performed to select the most stable isomer of H33342 for the overall charges 0, +1, and +2, expected to predominate across the 5 < pH < 10 range. The interaction of these isomers with POPC bilayers was then studied by both unrestrained and umbrella sampling molecular dynamics (MD) simulations. Both experimental results and computational free energy profiles indicate that the partition coefficient of H33342 displays a small variation over a wide pH range, not exceeding one order of magnitude. The enthalpy variation upon partition to the membrane suggests efficient hydrogen bonding between the probe and the lipid, namely, for the protonated +2 form, which was confirmed in the MD simulation studies. The relatively high lipophilicity obtained for the charged species contrasts with the decrease in their general hydrophobicity as estimated from octanol/water partition. This highlights the distinction between lipophilicity and hydrophobicity, as well as the importance of considering the association with lipid bilayers when predicting the affinity for biomembranes.
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Affiliation(s)
- Margarida M. Cordeiro
- Coimbra Chemistry Center, Institute of Molecular Sciences (CQC-IMS), University of Coimbra, 3004-535 Coimbra, Portugal; (M.M.C.); (H.A.L.F.); (J.S.)
- Department of Chemistry, Faculty of Sciences and Technology, University of Coimbra, 3004-535 Coimbra, Portugal
| | - Hugo A. L. Filipe
- Coimbra Chemistry Center, Institute of Molecular Sciences (CQC-IMS), University of Coimbra, 3004-535 Coimbra, Portugal; (M.M.C.); (H.A.L.F.); (J.S.)
- Polytechnic of Guarda, CPIRN-IPG—Center of Potential and Innovation of Natural Resources, 6300-559 Guarda, Portugal
| | - Patrícia dos Santos
- Coimbra Chemistry Center, Institute of Molecular Sciences (CQC-IMS), University of Coimbra, 3004-535 Coimbra, Portugal; (M.M.C.); (H.A.L.F.); (J.S.)
- Department of Chemistry, Faculty of Sciences and Technology, University of Coimbra, 3004-535 Coimbra, Portugal
| | - Jaime Samelo
- Coimbra Chemistry Center, Institute of Molecular Sciences (CQC-IMS), University of Coimbra, 3004-535 Coimbra, Portugal; (M.M.C.); (H.A.L.F.); (J.S.)
- Department of Chemistry, Faculty of Sciences and Technology, University of Coimbra, 3004-535 Coimbra, Portugal
| | - João P. Prates Ramalho
- LAQV, REQUIMTE, Hercules Laboratory, Department of Chemistry, School of Science and Technology, University of Évora, 7000-671 Évora, Portugal;
| | - Luís M. S. Loura
- Coimbra Chemistry Center, Institute of Molecular Sciences (CQC-IMS), University of Coimbra, 3004-535 Coimbra, Portugal; (M.M.C.); (H.A.L.F.); (J.S.)
- CNC—Center for Neuroscience and Cell Biology, University of Coimbra, 3004-535 Coimbra, Portugal
- Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra, Portugal
| | - Maria J. Moreno
- Coimbra Chemistry Center, Institute of Molecular Sciences (CQC-IMS), University of Coimbra, 3004-535 Coimbra, Portugal; (M.M.C.); (H.A.L.F.); (J.S.)
- Department of Chemistry, Faculty of Sciences and Technology, University of Coimbra, 3004-535 Coimbra, Portugal
- CNC—Center for Neuroscience and Cell Biology, University of Coimbra, 3004-535 Coimbra, Portugal
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9
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Wort JL, Ackermann K, Giannoulis A, Bode BE. Enhanced sensitivity for pulse dipolar EPR spectroscopy using variable-time RIDME. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 352:107460. [PMID: 37167826 DOI: 10.1016/j.jmr.2023.107460] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 04/03/2023] [Accepted: 04/19/2023] [Indexed: 05/13/2023]
Abstract
Pulse dipolar EPR spectroscopy (PDS) measurements are an important complementary tool in structural biology and are increasingly applied to macromolecular assemblies implicated in human health and disease at physiological concentrations. This requires ever higher sensitivity, and recent advances have driven PDS measurements into the mid-nanomolar concentration regime, though optimization and acquisition of such measurements remains experimentally demanding and time expensive. One important consideration is that constant-time acquisition represents a hard limit for measurement sensitivity, depending on the maximum measured distance. Determining this distance a priori has been facilitated by machine-learning structure prediction (AlphaFold2 and RoseTTAFold) but is often confounded by non-representative behaviour in frozen solution that may mandate multiple rounds of optimization and acquisition. Herein, we endeavour to simultaneously enhance sensitivity and streamline PDS measurement optimization to one-step by benchmarking a variable-time acquisition RIDME experiment applied to CuII-nitroxide and CuII-CuII model systems. Results demonstrate marked sensitivity improvements of both 5- and 6-pulse variable-time RIDME of between 2- and 5-fold over the constant-time analogues.
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Affiliation(s)
- Joshua L Wort
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews, Scotland
| | - Katrin Ackermann
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews, Scotland
| | - Angeliki Giannoulis
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews, Scotland
| | - Bela E Bode
- EaStCHEM School of Chemistry, Biomedical Sciences Research Complex and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews, Scotland.
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10
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Hydrogen-deuterium exchange coupled to mass spectrometry: A multifaceted tool to decipher the molecular mechanism of transporters. Biochimie 2023; 205:95-101. [PMID: 36037883 DOI: 10.1016/j.biochi.2022.08.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 08/17/2022] [Accepted: 08/19/2022] [Indexed: 11/22/2022]
Abstract
Transporters regulate trafficking through the biological membrane of living cells and organelles. Therefore, these proteins play an important role in key cellular processes. Obtaining a molecular-level description of the mechanism of transporters is highly desirable to understand and modulate such processes. Different challenges currently complicate this effort, mostly due to transporters' intrinsic properties. They are dynamic and often averse to in vitro characterization. The crossing of the membrane via a transporter depends on both global and local structural changes that will enable substrate binding from one side of the membrane and release on the other. Dedicated approaches are required to monitor these dynamic changes, ideally within the complex membrane environment. Hydrogen-deuterium exchange coupled to mass spectrometry (HDX-MS) has recently emerged as a powerful biophysical tool to understand transporters' mechanism. This mini-review aims to offer to the reader an overview of the field of HDX-MS applied to transporters. It first summarizes the current workflow for HDX-MS measurements on transporters. It then provides illustrative examples on the molecular insights that are accessible thanks to the technique; following conformational transitions between different states, observing structural changes upon ligand binding and finally understanding the role of lipid-protein interactions.
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11
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Li J, Zheng W, Gu M, Han L, Luo Y, Yu K, Sun M, Zong Y, Ma X, Liu B, Lowder EP, Mendez DL, Kranz RG, Zhang K, Zhu J. Structures of the CcmABCD heme release complex at multiple states. Nat Commun 2022; 13:6422. [PMID: 36307425 PMCID: PMC9616876 DOI: 10.1038/s41467-022-34136-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 10/14/2022] [Indexed: 12/25/2022] Open
Abstract
Cytochromes c use heme as a cofactor to carry electrons in respiration and photosynthesis. The cytochrome c maturation system I, consisting of eight membrane proteins (CcmABCDEFGH), results in the attachment of heme to cysteine residues of cytochrome c proteins. Since all c-type cytochromes are periplasmic, heme is first transported to a periplasmic heme chaperone, CcmE. A large membrane complex, CcmABCD has been proposed to carry out this transport and linkage to CcmE, yet the structural basis and mechanisms underlying the process are unknown. We describe high resolution cryo-EM structures of CcmABCD in an unbound form, in complex with inhibitor AMP-PNP, and in complex with ATP and heme. We locate the ATP-binding site in CcmA and the heme-binding site in CcmC. Based on our structures combined with functional studies, we propose a hypothetic model of heme trafficking, heme transfer to CcmE, and ATP-dependent release of holoCcmE from CcmABCD. CcmABCD represents an ABC transporter complex using the energy of ATP hydrolysis for the transfer of heme from one binding partner (CcmC) to another (CcmE).
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Affiliation(s)
- Jiao Li
- grid.410745.30000 0004 1765 1045School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023 China ,grid.47100.320000000419368710Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511 USA
| | - Wan Zheng
- grid.410745.30000 0004 1765 1045School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023 China
| | - Ming Gu
- grid.410745.30000 0004 1765 1045School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023 China
| | - Long Han
- grid.47100.320000000419368710Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511 USA
| | - Yanmei Luo
- grid.410745.30000 0004 1765 1045School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023 China
| | - Koukou Yu
- grid.410745.30000 0004 1765 1045School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023 China
| | - Mengxin Sun
- grid.410745.30000 0004 1765 1045School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023 China
| | - Yuliang Zong
- grid.410745.30000 0004 1765 1045School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023 China
| | - Xiuxiu Ma
- grid.410745.30000 0004 1765 1045School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023 China
| | - Bing Liu
- grid.410745.30000 0004 1765 1045School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023 China
| | - Ethan P. Lowder
- grid.4367.60000 0001 2355 7002Department of Biology, Washington University in St. Louis, CB 1137, One Brookings Drive, St. Louis, MO 63130-4899 USA
| | - Deanna L. Mendez
- grid.4367.60000 0001 2355 7002Department of Biology, Washington University in St. Louis, CB 1137, One Brookings Drive, St. Louis, MO 63130-4899 USA
| | - Robert G. Kranz
- grid.4367.60000 0001 2355 7002Department of Biology, Washington University in St. Louis, CB 1137, One Brookings Drive, St. Louis, MO 63130-4899 USA
| | - Kai Zhang
- grid.47100.320000000419368710Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511 USA
| | - Jiapeng Zhu
- grid.410745.30000 0004 1765 1045School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023 China
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12
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Hofmann L, Ruthstein S. EPR Spectroscopy Provides New Insights into Complex Biological Reaction Mechanisms. J Phys Chem B 2022; 126:7486-7494. [PMID: 36137278 PMCID: PMC9549461 DOI: 10.1021/acs.jpcb.2c05235] [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] [Indexed: 11/29/2022]
Abstract
![]()
In the last 20 years, the use of electron paramagnetic
resonance
(EPR) has made a pronounced and lasting impact in the field of structural
biology. The advantage of EPR spectroscopy over other structural techniques
is its ability to target even minor conformational changes in any
biomolecule or macromolecular complex, independent of its size or
complexity, or whether it is in solution or in the cell during a biological
or chemical reaction. Here, we focus on the use of EPR spectroscopy
to study transmembrane transport and transcription mechanisms. We
discuss experimental and analytical concerns when referring to studies
of two biological reaction mechanisms, namely, transfer of copper
ions by the human copper transporter hCtr1 and the mechanism of action
of the Escherichia coli copper-dependent
transcription factor CueR. Last, we elaborate on future avenues in
the field of EPR structural biology.
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Affiliation(s)
- Lukas Hofmann
- Department of Chemistry and the Institute of Nanotechnology & Advanced Materials, Faculty of Exact Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Sharon Ruthstein
- Department of Chemistry and the Institute of Nanotechnology & Advanced Materials, Faculty of Exact Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
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13
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Takada H, Mandell ZF, Yakhnin H, Glazyrina A, Chiba S, Kurata T, Wu KJY, Tresco BIC, Myers AG, Aktinson GC, Babitzke P, Hauryliuk V. Expression of Bacillus subtilis ABCF antibiotic resistance factor VmlR is regulated by RNA polymerase pausing, transcription attenuation, translation attenuation and (p)ppGpp. Nucleic Acids Res 2022; 50:6174-6189. [PMID: 35699226 PMCID: PMC9226507 DOI: 10.1093/nar/gkac497] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 05/22/2022] [Accepted: 05/26/2022] [Indexed: 12/14/2022] Open
Abstract
Since antibiotic resistance is often associated with a fitness cost, bacteria employ multi-layered regulatory mechanisms to ensure that expression of resistance factors is restricted to times of antibiotic challenge. In Bacillus subtilis, the chromosomally-encoded ABCF ATPase VmlR confers resistance to pleuromutilin, lincosamide and type A streptogramin translation inhibitors. Here we show that vmlR expression is regulated by translation attenuation and transcription attenuation mechanisms. Antibiotic-induced ribosome stalling during translation of an upstream open reading frame in the vmlR leader region prevents formation of an anti-antiterminator structure, leading to the formation of an antiterminator structure that prevents intrinsic termination. Thus, transcription in the presence of antibiotic induces vmlR expression. We also show that NusG-dependent RNA polymerase pausing in the vmlR leader prevents leaky expression in the absence of antibiotic. Furthermore, we demonstrate that induction of VmlR expression by compromised protein synthesis does not require the ability of VmlR to rescue the translational defect, as exemplified by constitutive induction of VmlR by ribosome assembly defects. Rather, the specificity of induction is determined by the antibiotic's ability to stall the ribosome on the regulatory open reading frame located within the vmlR leader. Finally, we demonstrate the involvement of (p)ppGpp-mediated signalling in antibiotic-induced VmlR expression.
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Affiliation(s)
- Hiraku Takada
- Faculty of Life Sciences, Kyoto Sangyo University and Institute for Protein Dynamics, Kamigamo, Motoyama, Kita-ku, Kyoto 603-8555, Japan.,Department of Experimental Medical Science, Lund University, 221 00 Lund, Sweden.,Department of Molecular Biology, Umeå University, Building 6K, 6L University Hospital Area, 90187 Umeå, Sweden
| | - Zachary F Mandell
- Department of Biochemistry and Molecular Biology, Center for RNA Molecular Biology, Pennsylvania State University, University Park, PA, USA
| | - Helen Yakhnin
- Department of Biochemistry and Molecular Biology, Center for RNA Molecular Biology, Pennsylvania State University, University Park, PA, USA
| | - Anastasiya Glazyrina
- Department of Molecular Biology, Umeå University, Building 6K, 6L University Hospital Area, 90187 Umeå, Sweden
| | - Shinobu Chiba
- Faculty of Life Sciences, Kyoto Sangyo University and Institute for Protein Dynamics, Kamigamo, Motoyama, Kita-ku, Kyoto 603-8555, Japan
| | - Tatsuaki Kurata
- Department of Experimental Medical Science, Lund University, 221 00 Lund, Sweden
| | - Kelvin J Y Wu
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Ben I C Tresco
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Andrew G Myers
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Gemma C Aktinson
- Department of Experimental Medical Science, Lund University, 221 00 Lund, Sweden
| | - Paul Babitzke
- Department of Biochemistry and Molecular Biology, Center for RNA Molecular Biology, Pennsylvania State University, University Park, PA, USA
| | - Vasili Hauryliuk
- Department of Experimental Medical Science, Lund University, 221 00 Lund, Sweden.,Department of Molecular Biology, Umeå University, Building 6K, 6L University Hospital Area, 90187 Umeå, Sweden.,University of Tartu, Institute of Technology, 50411, Tartu, Estonia
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