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Zhou Q, Catalán P, Bell H, Baumann P, Cooke R, Evans R, Yang J, Zhang Z, Zappalà D, Zhang Y, Blackburn GM, He Y, Jin Y. An Ion-Pair Induced Intermediate Complex Captured in Class D Carbapenemase Reveals Chloride Ion as a Janus Effector Modulating Activity. ACS CENTRAL SCIENCE 2023; 9:2339-2349. [PMID: 38161376 PMCID: PMC10755735 DOI: 10.1021/acscentsci.3c00609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 11/17/2023] [Accepted: 11/17/2023] [Indexed: 01/03/2024]
Abstract
Antibiotic-resistant Enterobacterales that produce oxacillinase (OXA)-48-like Class D β-lactamases are often linked to increased clinical mortality. Though the catalytic mechanism of OXA-48 is known, the molecular origin of its biphasic kinetics has been elusive. We here identify selective chloride binding rather than decarbamylation of the carbamylated lysine as the source of biphasic kinetics, utilizing isothermal titration calorimetry (ITC) to monitor the complete reaction course with the OXA-48 variant having a chemically stable N-acetyl lysine. Further structural investigation enables us to capture an unprecedented inactive acyl intermediate wedged in place by a halide ion paired with a conserved active site arginine. Supported by mutagenesis and mathematical simulation, we identify chloride as a "Janus effector" that operates by allosteric activation of the burst phase and by inhibition of the steady state in kinetic assays of β-lactams. We show that chloride-induced biphasic kinetics directly affects antibiotic efficacy and facilitates the differentiation of clinical isolates encoding Class D from Class A and B carbapenemases. As chloride is present in laboratory and clinical procedures, our discovery greatly expands the roles of chloride in modulating enzyme catalysis and highlights its potential impact on the pharmacokinetics and efficacy of antibiotics during in vivo treatment.
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Affiliation(s)
- Qi Zhou
- Key
Laboratory of Synthetic and Natural Functional Molecule, College of
Chemistry and Materials Science, Northwest
University, Xi’an 710127, P. R. China
| | - Pablo Catalán
- Grupo
Interdisciplinar de Sistemas Complejos, Departamento de Matemáticas, Universidad Carlos III de Madrid, 28911 Leganés, Spain
| | - Helen Bell
- School
of Chemistry, Cardiff University, Cardiff, CF10 3AT, United Kingdom
| | - Patrick Baumann
- School
of Chemistry, Cardiff University, Cardiff, CF10 3AT, United Kingdom
- Manchester
Institute of Biotechnology, University of
Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Rebekah Cooke
- School
of Chemistry, Cardiff University, Cardiff, CF10 3AT, United Kingdom
| | - Rhodri Evans
- School
of Chemistry, Cardiff University, Cardiff, CF10 3AT, United Kingdom
- Manchester
Institute of Biotechnology, University of
Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Jianhua Yang
- Key
Laboratory of Synthetic and Natural Functional Molecule, College of
Chemistry and Materials Science, Northwest
University, Xi’an 710127, P. R. China
| | - Zhen Zhang
- Key
Laboratory of Synthetic and Natural Functional Molecule, College of
Chemistry and Materials Science, Northwest
University, Xi’an 710127, P. R. China
- School
of Chemistry, Cardiff University, Cardiff, CF10 3AT, United Kingdom
| | - Davide Zappalà
- School
of Chemistry, Cardiff University, Cardiff, CF10 3AT, United Kingdom
| | - Ye Zhang
- Key
Laboratory of Synthetic and Natural Functional Molecule, College of
Chemistry and Materials Science, Northwest
University, Xi’an 710127, P. R. China
| | - George Michael Blackburn
- School
of Biosciences, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, United Kingdom
| | - Yuan He
- Key
Laboratory of Synthetic and Natural Functional Molecule, College of
Chemistry and Materials Science, Northwest
University, Xi’an 710127, P. R. China
| | - Yi Jin
- School
of Chemistry, Cardiff University, Cardiff, CF10 3AT, United Kingdom
- Manchester
Institute of Biotechnology, University of
Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
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Li C, Yin L, He X, Jin Y, Zhu X, Wu R. Competition-cooperation mechanism between Escherichia coli and Staphylococcus aureus based on systems mapping. Front Microbiol 2023; 14:1192574. [PMID: 38029174 PMCID: PMC10657823 DOI: 10.3389/fmicb.2023.1192574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 10/23/2023] [Indexed: 12/01/2023] Open
Abstract
Introduction Interspecies interactions are a crucial driving force of species evolution. The genes of each coexisting species play a pivotal role in shaping the structure and function within the community, but how to identify them at the genome-wide level has always been challenging. Methods In this study, we embed the Lotka-Volterra ordinary differential equations in the theory of community ecology into the systems mapping model, so that this model can not only describe how the quantitative trait loci (QTL) of a species directly affects its own phenotype, but also describe the QTL of the species how to indirectly affect the phenotype of its interacting species, and how QTL from different species affects community behavior through epistatic interactions. Results By designing and implementing a co-culture experiment for 100 pairs of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), we mapped 244 significant QTL combinations in the interaction process of the two bacteria using this model, including 69 QTLs from E. coli and 59 QTLs from S. aureus, respectively. Through gene annotation, we obtained 57 genes in E. coli, among which the genes with higher frequency were ypdC, nrfC, yphH, acrE, dcuS, rpnE, and ptsA, while we obtained 43 genes in S. aureus, among which the genes with higher frequency were ebh, SAOUHSC_00172, capF, gdpP, orfX, bsaA, and phnE1. Discussion By dividing the overall growth into independent growth and interactive growth, we could estimate how QTLs modulate interspecific competition and cooperation. Based on the quantitative genetic model, we can obtain the direct genetic effect, indirect genetic effect, and genome-genome epistatic effect related to interspecific interaction genes, and then further mine the hub genes in the QTL networks, which will be particularly useful for inferring and predicting the genetic mechanisms of community dynamics and evolution. Systems mapping can provide a tool for studying the mechanism of competition and cooperation among bacteria in co-culture, and this framework can lay the foundation for a more comprehensive and systematic study of species interactions.
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Affiliation(s)
- Caifeng Li
- Center for Computational Biology, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
| | - Lixin Yin
- Center for Computational Biology, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
| | - Xiaoqing He
- Center for Computational Biology, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
- National Engineering Laboratory for Tree Breeding, Beijing Forestry University, Beijing, China
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants, Ministry of Education, Beijing Forestry University, Beijing, China
- The Tree and Ornamental Plant Breeding and Biotechnology, Laboratory of National Forestry and Grassland Administration, Beijing Forestry University, Beijing, China
| | - Yi Jin
- Center for Computational Biology, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
- National Engineering Laboratory for Tree Breeding, Beijing Forestry University, Beijing, China
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants, Ministry of Education, Beijing Forestry University, Beijing, China
- The Tree and Ornamental Plant Breeding and Biotechnology, Laboratory of National Forestry and Grassland Administration, Beijing Forestry University, Beijing, China
| | - Xuli Zhu
- Center for Computational Biology, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
- National Engineering Laboratory for Tree Breeding, Beijing Forestry University, Beijing, China
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants, Ministry of Education, Beijing Forestry University, Beijing, China
- The Tree and Ornamental Plant Breeding and Biotechnology, Laboratory of National Forestry and Grassland Administration, Beijing Forestry University, Beijing, China
| | - Rongling Wu
- Center for Computational Biology, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
- National Engineering Laboratory for Tree Breeding, Beijing Forestry University, Beijing, China
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants, Ministry of Education, Beijing Forestry University, Beijing, China
- The Tree and Ornamental Plant Breeding and Biotechnology, Laboratory of National Forestry and Grassland Administration, Beijing Forestry University, Beijing, China
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Miller E, Mai BK, Read JA, Bell WC, Derrick JS, Liu P, Toste FD. A Combined DFT, Energy Decomposition, and Data Analysis Approach to Investigate the Relationship Between Noncovalent Interactions and Selectivity in a Flexible DABCOnium/Chiral Anion Catalyst System. ACS Catal 2022; 12:12369-12385. [PMID: 37215160 PMCID: PMC10195112 DOI: 10.1021/acscatal.2c03077] [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] [Indexed: 11/30/2022]
Abstract
Developing strategies to study reactivity and selectivity in flexible catalyst systems has become an important topic of research. Herein, we report a combined experimental and computational study aimed at understanding the mechanistic role of an achiral DABCOnium cofactor in a regio- and enantiodivergent bromocyclization reaction. It was found that electron-deficient aryl substituents enable rigidified transition states via an anion-π interaction with the catalyst, which drives the selectivity of the reaction. In contrast, electron-rich aryl groups on the DABCOnium result in significantly more flexible transition states, where interactions between the catalyst and substrate are more important. An analysis of not only the lowest-energy transition state structures but also an ensemble of low-energy transition state conformers via energy decomposition analysis and machine learning was crucial to revealing the dominant noncovalent interactions responsible for observed changes in selectivity in this flexible system.
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Affiliation(s)
- Edward Miller
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Binh Khanh Mai
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Jacquelyne A Read
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - William C Bell
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Jeffrey S Derrick
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Peng Liu
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - F Dean Toste
- Department of Chemistry, University of California, Berkeley, California 94720, United States
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4
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Johnson TW, Bolanos B, Brooun A, Gallego RA, Gehlhaar D, Jalaie M, McTigue M, Timofeevski S. Reviving B-Factors: Activating ALK Mutations Increase Protein Dynamics of the Unphosphorylated Kinase. ACS Med Chem Lett 2018; 9:872-877. [PMID: 30258533 DOI: 10.1021/acsmedchemlett.8b00348] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 08/24/2018] [Indexed: 12/14/2022] Open
Abstract
Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase that can become oncogenic by activating mutations or overexpression. Full kinetic characterization of both phosphorylated and nonphosphorylated wildtype and mutant ALK kinase domain was done. Our structure-based drug design programs directed at ALK allowed us to interrogate whether X-ray crystallography data could be used to support the hypothesis that activation of ALK by mutation occurs due to increased protein dynamics. Crystallographic B-factors were converted to normalized B-factors, which allowed analysis of wildtype ALK, ALK-C1156Y, and ALK-L1196M. This data suggests that mobility of the P-loop, αC-helix, and activation loop (A-loop) may be important in catalytic activity increases, with or without phosphorylation. Both molecular dynamics simulations and hydrogen-deuterium exchange experimental data corroborated the normalized B-factors data.
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Affiliation(s)
- Ted W. Johnson
- Pfizer Worldwide Research and Development, La Jolla Oncology, 10770 Science Center Drive, San Diego, California 92121, United States
| | - Ben Bolanos
- Pfizer Worldwide Research and Development, La Jolla Oncology, 10770 Science Center Drive, San Diego, California 92121, United States
| | - Alexei Brooun
- Pfizer Worldwide Research and Development, La Jolla Oncology, 10770 Science Center Drive, San Diego, California 92121, United States
| | - Rebecca A. Gallego
- Pfizer Worldwide Research and Development, La Jolla Oncology, 10770 Science Center Drive, San Diego, California 92121, United States
| | - Dan Gehlhaar
- Pfizer Worldwide Research and Development, La Jolla Oncology, 10770 Science Center Drive, San Diego, California 92121, United States
| | - Mehran Jalaie
- Pfizer Worldwide Research and Development, La Jolla Oncology, 10770 Science Center Drive, San Diego, California 92121, United States
| | - Michele McTigue
- Pfizer Worldwide Research and Development, La Jolla Oncology, 10770 Science Center Drive, San Diego, California 92121, United States
| | - Sergei Timofeevski
- Pfizer Worldwide Research and Development, La Jolla Oncology, 10770 Science Center Drive, San Diego, California 92121, United States
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5
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Kuzmanic A, Pannu NS, Zagrovic B. X-ray refinement significantly underestimates the level of microscopic heterogeneity in biomolecular crystals. Nat Commun 2015; 5:3220. [PMID: 24504120 PMCID: PMC3926004 DOI: 10.1038/ncomms4220] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 01/07/2014] [Indexed: 11/09/2022] Open
Abstract
Biomolecular X-ray structures typically provide a static, time- and ensemble-averaged view of molecular ensembles in crystals. In the absence of rigid-body motions and lattice defects, B-factors are thought to accurately reflect the structural heterogeneity of such ensembles. In order to study the effects of averaging on B-factors, we employ molecular dynamics simulations to controllably manipulate microscopic heterogeneity of a crystal containing 216 copies of villin headpiece. Using average structure factors derived from simulation, we analyse how well this heterogeneity is captured by high-resolution molecular-replacement-based model refinement. We find that both isotropic and anisotropic refined B-factors often significantly deviate from their actual values known from simulation: even at high 1.0 Å resolution and Rfree of 5.9%, B-factors of some well-resolved atoms underestimate their actual values even sixfold. Our results suggest that conformational averaging and inadequate treatment of correlated motion considerably influence estimation of microscopic heterogeneity via B-factors, and invite caution in their interpretation.
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Affiliation(s)
- Antonija Kuzmanic
- Department of Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, Campus Vienna Biocenter 5, A-1030 Vienna, Austria
| | - Navraj S Pannu
- Biophysical Structural Chemistry, Leiden University, PO Box 9502, 2300 RA Leiden, The Netherlands
| | - Bojan Zagrovic
- Department of Structural and Computational Biology, Max F. Perutz Laboratories, University of Vienna, Campus Vienna Biocenter 5, A-1030 Vienna, Austria
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6
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Pantouris G, Syed MA, Fan C, Rajasekaran D, Cho TY, Rosenberg EM, Bucala R, Bhandari V, Lolis EJ. An Analysis of MIF Structural Features that Control Functional Activation of CD74. ACTA ACUST UNITED AC 2015; 22:1197-205. [PMID: 26364929 DOI: 10.1016/j.chembiol.2015.08.006] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 07/19/2015] [Accepted: 08/10/2015] [Indexed: 12/22/2022]
Abstract
For more than 15 years, the tautomerase active site of macrophage migration inhibitory factor (MIF) and its catalytic residue Pro1 have been being targeted for the development of therapeutics that block activation of its cell surface receptor, CD74. Neither the biological role of the MIF catalytic site nor the mechanistic details of CD74 activation are well understood. The inherently unstable structure of CD74 remains the biggest obstacle in structural studies with MIF for understanding the basis of CD74 activation. Using a novel approach, we elucidate the mechanistic details that control activation of CD74 by MIF surface residues and identify structural parameters of inhibitors that reduce CD74 biological activation. We also find that N-terminal mutants located deep in the catalytic site affect surface residues immediately outside the catalytic site, which are responsible for reduction of CD74 activation.
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Affiliation(s)
- Georgios Pantouris
- Department of Pharmacology, Yale School of Medicine, New Haven, CT 06510, USA
| | - Mansoor Ali Syed
- Department of Pediatrics, Yale School of Medicine, New Haven, CT 06510, USA
| | - Chengpeng Fan
- Department of Pharmacology, Yale School of Medicine, New Haven, CT 06510, USA
| | - Deepa Rajasekaran
- Department of Pharmacology, Yale School of Medicine, New Haven, CT 06510, USA
| | - Thomas Yoonsang Cho
- Department of Pharmacology, Yale School of Medicine, New Haven, CT 06510, USA
| | - Eric M Rosenberg
- Department of Pharmacology, Yale School of Medicine, New Haven, CT 06510, USA
| | - Richard Bucala
- Internal Medicine, Yale School of Medicine, New Haven, CT 06510, USA; Yale Cancer Center, Yale School of Medicine, New Haven, CT 06510, USA
| | - Vineet Bhandari
- Department of Pediatrics, Yale School of Medicine, New Haven, CT 06510, USA
| | - Elias J Lolis
- Department of Pharmacology, Yale School of Medicine, New Haven, CT 06510, USA; Yale Cancer Center, Yale School of Medicine, New Haven, CT 06510, USA.
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7
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Yamane T, Murakami S, Ikeguchi M. Functional rotation induced by alternating protonation states in the multidrug transporter AcrB: all-atom molecular dynamics simulations. Biochemistry 2013; 52:7648-58. [PMID: 24083838 DOI: 10.1021/bi400119v] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The multidrug transporter AcrB actively exports a wide variety of noxious compounds using proton-motive force as an energy source in Gram-negative bacteria. AcrB adopts an asymmetric structure comprising three protomers with different conformations that are sequentially converted during drug export; these cyclic conformational changes during drug export are referred to as functional rotation. To investigate functional rotation driven by proton-motive force, all-atom molecular dynamics simulations were performed. Using different protonation states for the titratable residues in the middle of the transmembrane domain, our simulations revealed the correlation between the specific protonation states and the side-chain configurations. Changing the protonation state for Asp408 induced a spontaneous structural transition, which suggests that the proton translocation stoichiometry may be one proton per functional rotation cycle. Furthermore, our simulations demonstrate that alternating the protonation states in the transmembrane domain induces functional rotation in the porter domain, which is primarily responsible for drug transport.
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Affiliation(s)
- Tsutomu Yamane
- Graduate School of Medical Life Science, Yokohama City University , 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan
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8
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Ren Z, Chan PWY, Moffat K, Pai EF, Royer WE, Šrajer V, Yang X. Resolution of structural heterogeneity in dynamic crystallography. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2013; 69:946-59. [PMID: 23695239 PMCID: PMC3663119 DOI: 10.1107/s0907444913003454] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 02/04/2013] [Indexed: 05/15/2024]
Abstract
Dynamic behavior of proteins is critical to their function. X-ray crystallography, a powerful yet mostly static technique, faces inherent challenges in acquiring dynamic information despite decades of effort. Dynamic `structural changes' are often indirectly inferred from `structural differences' by comparing related static structures. In contrast, the direct observation of dynamic structural changes requires the initiation of a biochemical reaction or process in a crystal. Both the direct and the indirect approaches share a common challenge in analysis: how to interpret the structural heterogeneity intrinsic to all dynamic processes. This paper presents a real-space approach to this challenge, in which a suite of analytical methods and tools to identify and refine the mixed structural species present in multiple crystallographic data sets have been developed. These methods have been applied to representative scenarios in dynamic crystallography, and reveal structural information that is otherwise difficult to interpret or inaccessible using conventional methods.
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Affiliation(s)
- Zhong Ren
- Center for Advanced Radiation Sources, The University of Chicago, 9700 South Cass Avenue, Building 434B, Argonne, IL 60439, USA.
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9
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Ruggerone P, Vargiu AV, Collu F, Fischer N, Kandt C. Molecular Dynamics Computer Simulations of Multidrug RND Efflux Pumps. Comput Struct Biotechnol J 2013; 5:e201302008. [PMID: 24688701 PMCID: PMC3962194 DOI: 10.5936/csbj.201302008] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 01/31/2013] [Accepted: 02/04/2013] [Indexed: 01/13/2023] Open
Abstract
Over-expression of multidrug efflux pumps of the Resistance Nodulation Division (RND) protein super family counts among the main causes for microbial resistance against pharmaceuticals. Understanding the molecular basis of this process is one of the major challenges of modern biomedical research, involving a broad range of experimental and computational techniques. Here we review the current state of RND transporter investigation employing molecular dynamics simulations providing conformational samples of transporter components to obtain insights into the functional mechanism underlying efflux pump-mediated antibiotics resistance in Escherichia coli and Pseudomonas aeruginosa.
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Affiliation(s)
- Paolo Ruggerone
- Department of Physics, University of Cagliari, Cittadella Universitaria S.P. Monserrato-Sestu Km 0.700, 09042 Monserrato (CA), Cagliari, Italy ; CNR-IOM, Unità SLACS, S.P. Monserrato-Sestu Km 0.700, I-09042 Monserrato (CA), Italy
| | - Attilio V Vargiu
- Department of Physics, University of Cagliari, Cittadella Universitaria S.P. Monserrato-Sestu Km 0.700, 09042 Monserrato (CA), Cagliari, Italy ; CNR-IOM, Unità SLACS, S.P. Monserrato-Sestu Km 0.700, I-09042 Monserrato (CA), Italy
| | - Francesca Collu
- Departement fu r Chemie und Biochemie, Universita t Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Nadine Fischer
- Computational Structural Biology, Department of Life Science Informatics B-IT, Life & Medical Sciences Institute, University of Bonn, Dahlmannstr. 2, 53113 Bonn, Germany
| | - Christian Kandt
- Computational Structural Biology, Department of Life Science Informatics B-IT, Life & Medical Sciences Institute, University of Bonn, Dahlmannstr. 2, 53113 Bonn, Germany
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10
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Fischer N, Kandt C. Porter domain opening and closing motions in the multi-drug efflux transporter AcrB. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:632-41. [PMID: 23088914 DOI: 10.1016/j.bbamem.2012.10.016] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 10/02/2012] [Accepted: 10/13/2012] [Indexed: 11/15/2022]
Abstract
Acriflavine resistance protein B acts as the active transporter in the multi-drug efflux pump Acriflavine resistance proteins A / B - Tolerance to colicins protein in Escherichia coli. Within the same reaction cycle intermediate all Acriflavine resistance protein B X-ray structures display highly similar conformations of the substrate-recruiting and transporting porter domain. To assess if this structural homogeneity is an intrinsic feature of Acriflavine resistance protein B or stems from other causes we performed a series of six independent, unbiased 100 ns molecular dynamics simulations of membrane-embedded, asymmetric, substrate-free wild type Acriflavine resistance protein B in a 150 mM NaCl solution. We find the porter domain more flexible than previously assumed displaying clear opening and closing motions of the proximal binding pocket (L and T-state) and the exit of the drug transport channels (O-intermediate). Concurrently the hydrophobic binding pocket favors a closed conformation in all three protomers. Our findings suggest that the conformational homogeneity seen in the crystal structures is likely an effect of bound but structurally unresolved substrate. Our simulations further imply that each of the known three reaction cycle intermediates occurs in at least two variants, the Thr676 loop independently regulates porter domain access and likely plays a key role in substrate transport. On a 100 ns time scale we find no evidence supporting the proposed LLL resting state in the absence of substrate. If the proximal binding pocket dynamics have an inhibiting effect on Acriflavine resistance protein B pump activity lowering the life time of substrate-accessible conformations, the observed dynamics could provide a structural explanation for the Acriflavine resistance protein B activity-enhancing effect of the adaptor protein Acriflavine resistance protein A stabilizing PC1 and PC2 subdomain orientations.
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Affiliation(s)
- Nadine Fischer
- Computational Structural Biology, Department of Life Science Informatics, B-IT, Life & Medical Sciences (LIMES) Institute, University of Bonn, Dahlmannstr 2, 53113 Bonn, Germany
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11
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Feng Z, Hou T, Li Y. Unidirectional peristaltic movement in multisite drug binding pockets of AcrB from molecular dynamics simulations. MOLECULAR BIOSYSTEMS 2012; 8:2699-709. [DOI: 10.1039/c2mb25184a] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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12
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Fischer N, Kandt C. Three ways in, one way out: water dynamics in the trans-membrane domains of the inner membrane translocase AcrB. Proteins 2011; 79:2871-85. [PMID: 21905112 DOI: 10.1002/prot.23122] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 06/03/2011] [Accepted: 07/10/2011] [Indexed: 01/21/2023]
Abstract
Powered by proton-motive force, the inner membrane translocase AcrB is the engine of the AcrAB-TolC efflux pump in Escherichia coli. As proton conduction in proteins occurs along hydrogen-bonded networks of polar residues and water molecules, knowledge of the protein-internal water distribution and water-interacting residues allows drawing conclusions to possible pathways of proton conduction. Here, we report a series of 6× 50 ns independent molecular dynamics simulations of asymmetric AcrB embedded in a phospholipid/water environment. Simulating each monomer in its proposed protonation state, we calculated for each trans-membrane domain the average water distribution, identified residues interacting with these waters and quantified each residue's frequency of water hydrogen bond contact. Combining this information we find three possible routes of proton transfer connecting a continuously hydrated region of known key residues in the TMD interior to bulk water by one cytoplasmic and up to three periplasm water channels in monomer B and A. We find that water access of the trans-membrane domains is regulated by four groups of residues in a combination of side chain re-orientations and shifts of trans-membrane helices. Our findings support a proton release event via Arg971 during the C intermediate or in the transition to A, and proton uptake occurring in the A or B state or during a so far unknown intermediate in between B and C where cytoplasmic water access is still possible. Our simulations suggest experimentally testable hypotheses, which have not been investigated so far.
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Affiliation(s)
- Nadine Fischer
- Computational Structural Biology, Department of Life Science Informatics B-IT, Life & Medical Sciences (LIMES) Center, University of Bonn, Bonn, Germany
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13
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Abstract
Membrane proteins play a key role in energy conversion, transport, signal recognition, transduction, and other fundamental biological processes. Despite considerable progress in experimental techniques, the determination of structure and dynamics of membrane proteins still represents a great challenge. Computer simulation methods are becoming an increasingly important tool not only in the interpretation of experiments but also in the prediction of membrane protein dynamics. In the present review, we give a brief introduction to molecular modeling techniques currently used to explore protein dynamics on time scales ranging from femtoseconds to microseconds. We then describe a few recent example applications of these techniques to membrane proteins. In conclusion, we also discuss some of the newest developments in simulation methodology that have the potential to further extend the time scale accessible to explore (membrane) protein dynamics.
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14
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Kuzmanic A, Zagrovic B. Determination of ensemble-average pairwise root mean-square deviation from experimental B-factors. Biophys J 2010; 98:861-71. [PMID: 20197040 DOI: 10.1016/j.bpj.2009.11.011] [Citation(s) in RCA: 264] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2009] [Revised: 10/30/2009] [Accepted: 11/03/2009] [Indexed: 11/19/2022] Open
Abstract
Root mean-square deviation (RMSD) after roto-translational least-squares fitting is a measure of global structural similarity of macromolecules used commonly. On the other hand, experimental x-ray B-factors are used frequently to study local structural heterogeneity and dynamics in macromolecules by providing direct information about root mean-square fluctuations (RMSF) that can also be calculated from molecular dynamics simulations. We provide a mathematical derivation showing that, given a set of conservative assumptions, a root mean-square ensemble-average of an all-against-all distribution of pairwise RMSD for a single molecular species, <RMSD(2)>(1/2), is directly related to average B-factors (<B>) and <RMSF(2)>(1/2). We show this relationship and explore its limits of validity on a heterogeneous ensemble of structures taken from molecular dynamics simulations of villin headpiece generated using distributed-computing techniques and the Folding@Home cluster. Our results provide a basis for quantifying global structural diversity of macromolecules in crystals directly from x-ray experiments, and we show this on a large set of structures taken from the Protein Data Bank. In particular, we show that the ensemble-average pairwise backbone RMSD for a microscopic ensemble underlying a typical protein x-ray structure is approximately 1.1 A, under the assumption that the principal contribution to experimental B-factors is conformational variability.
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Batista PR, Robert CH, Maréchal JD, Hamida-Rebaï MB, Pascutti PG, Bisch PM, Perahia D. Consensus modes, a robust description of protein collective motions from multiple-minima normal mode analysis—application to the HIV-1 protease. Phys Chem Chem Phys 2010; 12:2850-9. [DOI: 10.1039/b919148h] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Stember JN, Wriggers W. Bend-twist-stretch model for coarse elastic network simulation of biomolecular motion. J Chem Phys 2009; 131:074112. [PMID: 19708737 DOI: 10.1063/1.3167410] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The empirical harmonic potential function of elastic network models (ENMs) is augmented by three- and four-body interactions as well as by a parameter-free connection rule. In the new bend-twist-stretch (BTS) model the complexity of the parametrization is shifted from the spatial level of detail to the potential function, enabling an arbitrary coarse graining of the network. Compared to distance cutoff-based Hookean springs, the approach yields a more stable parametrization of coarse-grained ENMs for biomolecular dynamics. Traditional ENMs give rise to unbounded zero-frequency vibrations when (pseudo)atoms are connected to fewer than three neighbors. A large cutoff is therefore chosen in an ENM (about twice the average nearest-neighbor distance), resulting in many false-positive connections that reduce the spatial detail that can be resolved. More importantly, the required three-neighbor connectedness also limits the coarse graining, i.e., the network must be dense, even in the case of low-resolution structures that exhibit few spatial features. The new BTS model achieves such coarse graining by extending the ENM potential to include three-and four-atom interactions (bending and twisting, respectively) in addition to the traditional two-atom stretching. Thus, the BTS model enables reliable modeling of any three-dimensional graph irrespective of the atom connectedness. The additional potential terms were parametrized using continuum elastic theory of elastic rods, and the distance cutoff was replaced by a competitive Hebb connection rule, setting all free parameters in the model. We validate the approach on a carbon-alpha representation of adenylate kinase and illustrate its use with electron microscopy maps of E. coli RNA polymerase, E. coli ribosome, and eukaryotic chaperonin containing T-complex polypeptide 1, which were difficult to model with traditional ENMs. For adenylate kinase, we find excellent reproduction (>90% overlap) of the ENM modes and B factors when BTS is applied to the carbon-alpha representation as well as to coarser descriptions. For the volumetric maps, coarse BTS yields similar motions (70%-90% overlap) to those obtained from significantly denser representations with ENM. Our Python-based algorithms of ENM and BTS implementations are freely available.
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Affiliation(s)
- Joseph N Stember
- Department of Physiology and Biophysics and Institute for Computational Biomedicine, Weill Medical College of Cornell University, 1300 York Ave., New York, New York 10065, USA
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Abstract
Drug extrusion via efflux through a tripartite complex (an inner membrane pump, an outer membrane protein, and a periplasmic protein) is a widely used mechanism in Gram-negative bacteria. The outer membrane protein (TolC in Escherichia coli; OprM in Pseudomonas aeruginosa) forms a tunnel-like pore through the periplasmic space and the outer membrane. Molecular dynamics simulations of TolC have been performed, and are compared to simulations of Y362F/R367S mutant, and to simulations of its homolog OprM. The results reveal a complex pattern of conformation dynamics in the TolC protein. Two putative gate regions, located at either end of the protein, can be distinguished. These regions are the extracellular loops and the mouth of the periplasmic domain, respectively. The periplasmic gate has been implicated in the conformational changes leading from the closed x-ray structure to a proposed open state of TolC. Between the two gates, a peristaltic motion of the periplasmic domain is observed, which may facilitate transport of the solutes from one end of the tunnel to the other. The motions observed in the atomistic simulations are also seen in coarse-grained simulations in which the protein tertiary structure is represented by an elastic network model.
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Jones PM, George AM. Nucleotide-dependent allostery within the ABC transporter ATP-binding cassette: a computational study of the MJ0796 dimer. J Biol Chem 2007; 282:22793-803. [PMID: 17485460 DOI: 10.1074/jbc.m700809200] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
ATP-binding cassette transporters perform energy-dependent transmembrane solute trafficking in all organisms. These proteins often mediate cellular resistance to therapeutic drugs and are involved in a range of human genetic diseases. Enzymological studies have implicated a helical subdomain within the ATP-binding cassette nucleotide-binding domain in coupling ATP hydrolysis to solute transport in the transmembrane domains. Consistent with this, structural and computational analyses have indicated that the helical subdomain undergoes nucleotide-dependent movement relative to the core of the nucleotide-binding domain fold. Here we use theoretical methods to examine the allosteric nucleotide dependence of helical subdomain transitions to further elucidate its role in interactions between the transmembrane and nucleotide-binding domains. Unrestrained 30-ns molecular dynamics simulations of the ATP-bound, ADP-bound, and apo states of the MJ0796 monomer support the idea that interaction of a conserved glutamine residue with the catalytic metal mediates the rotation of the helical subdomain in response to nucleotide binding and hydrolysis. Simulations of the nucleotide-binding domain dimer revealed that ATP hydrolysis induces a large transition of one helical subdomain, resulting in an asymmetric conformation of the dimer not observed previously. A coarse-grained elastic network analysis supports this finding, revealing the existence of corresponding dynamic modes intrinsic to the contact topology of the protein. The implications of these findings for the coupling of ATP hydrolysis to conformational changes in the transmembrane domains required for solute transport are discussed in light of recent whole transporter structures.
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Affiliation(s)
- Peter M Jones
- Department of Medical and Molecular Biosciences, Faculty of Science, University of Technology Sydney, P. O. Box 123, Broadway, New South Wales 2007, Australia
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Su CC, Li M, Gu R, Takatsuka Y, McDermott G, Nikaido H, Yu EW. Conformation of the AcrB multidrug efflux pump in mutants of the putative proton relay pathway. J Bacteriol 2006; 188:7290-6. [PMID: 17015668 PMCID: PMC1636240 DOI: 10.1128/jb.00684-06] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We previously reported the X-ray structures of wild-type Escherichia coli AcrB, a proton motive force-dependent multidrug efflux pump, and its N109A mutant. These structures presumably reflect the resting state of AcrB, which can bind drugs. After ligand binding, a proton may bind to an acidic residue(s) in the transmembrane domain, i.e., Asp407 or Asp408, within the putative network of electrostatically interacting residues, which also include Lys940 and Thr978, and this may initiate a series of conformational changes that result in drug expulsion. Herein we report the X-ray structures of four AcrB mutants, the D407A, D408A, K940A, and T978A mutants, in which the structure of this tight electrostatic network is expected to become disrupted. These mutant proteins revealed remarkably similar conformations, which show striking differences from the previously known conformations of the wild-type protein. For example, the loop containing Phe386 and Phe388, which play a major role in the initial binding of substrates in the central cavity, becomes prominently extended into the center of the cavity, such that binding of large substrate molecules may become difficult. We believe that this new conformation may mimic, at least partially, one of the transient conformations of the transporter during the transport cycle.
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Affiliation(s)
- Chih-Chia Su
- Department of Molecular and Cell Biology, 16 Barker Hall, University of California, Berkeley, CA 94720-3202, USA
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