1
|
Janet-Maitre M, Job V, Bour M, Robert-Genthon M, Brugière S, Triponney P, Cobessi D, Couté Y, Jeannot K, Attrée I. Pseudomonas aeruginosa MipA-MipB envelope proteins act as new sensors of polymyxins. mBio 2024; 15:e0221123. [PMID: 38345374 PMCID: PMC10936184 DOI: 10.1128/mbio.02211-23] [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: 08/16/2023] [Accepted: 01/09/2024] [Indexed: 03/14/2024] Open
Abstract
Due to the rising incidence of antibiotic-resistant infections, the last-line antibiotics, polymyxins, have resurged in the clinics in parallel with new bacterial strategies of escape. The Gram-negative opportunistic pathogen Pseudomonas aeruginosa develops resistance to colistin/polymyxin B by distinct molecular mechanisms, mostly through modification of the lipid A component of the LPS by proteins encoded within the arnBCDATEF-ugd (arn) operon. In this work, we characterized a polymyxin-induced operon named mipBA, present in P. aeruginosa strains devoid of the arn operon. We showed that mipBA is activated by the ParR/ParS two-component regulatory system in response to polymyxins. Structural modeling revealed that MipA folds as an outer-membrane β-barrel, harboring an internal negatively charged channel, able to host a polymyxin molecule, while the lipoprotein MipB adopts a β-lactamase fold with two additional C-terminal domains. Experimental work confirmed that MipA and MipB localize to the bacterial envelope, and they co-purify in vitro. Nano differential scanning fluorimetry showed that polymyxins stabilized MipA in a specific and dose-dependent manner. Mass spectrometry-based quantitative proteomics on P. aeruginosa membranes demonstrated that ∆mipBA synthesized fourfold less MexXY-OprA proteins in response to polymyxin B compared to the wild-type strain. The decrease was a direct consequence of impaired transcriptional activation of the mex operon operated by ParR/ParS. We propose MipA/MipB to act as membrane (co)sensors working in concert to activate ParS histidine kinase and help the bacterium to cope with polymyxin-mediated envelope stress through synthesis of the efflux pump, MexXY-OprA.IMPORTANCEDue to the emergence of multidrug-resistant isolates, antibiotic options may be limited to polymyxins to eradicate Gram-negative infections. Pseudomonas aeruginosa, a leading opportunistic pathogen, has the ability to develop resistance to these cationic lipopeptides by modifying its lipopolysaccharide through proteins encoded within the arn operon. Herein, we describe a sub-group of P. aeruginosa strains lacking the arn operon yet exhibiting adaptability to polymyxins. Exposition to sub-lethal polymyxin concentrations induced the expression and production of two envelope-associated proteins. Among those, MipA, an outer-membrane barrel, is able to specifically bind polymyxins with an affinity in the 10-µM range. Using membrane proteomics and phenotypic assays, we showed that MipA and MipB participate in the adaptive response to polymyxins via ParR/ParS regulatory signaling. We propose a new model wherein the MipA-MipB module functions as a novel polymyxin sensing mechanism.
Collapse
Affiliation(s)
- Manon Janet-Maitre
- Team Bacterial Pathogenesis and Cellular Responses, University Grenoble Alpes, IBS, UMR5075, Grenoble, France
| | - Viviana Job
- Team Bacterial Pathogenesis and Cellular Responses, University Grenoble Alpes, IBS, UMR5075, Grenoble, France
| | - Maxime Bour
- UMR6249 Chrono-Environnement, UFR Santé, University of Franche-Comté, Besançon, France
- French National Reference Center for Antibiotic Resistance, Besançon, France
| | - Mylène Robert-Genthon
- Team Bacterial Pathogenesis and Cellular Responses, University Grenoble Alpes, IBS, UMR5075, Grenoble, France
| | - Sabine Brugière
- University Grenoble Alpes, CEA, INSERM, UA13 BGE, CNRS, CEA, FranceGrenoble
| | - Pauline Triponney
- French National Reference Center for Antibiotic Resistance, Besançon, France
| | - David Cobessi
- University Grenoble Alpes, IBS, UMR5075, Team Synchrotron, Grenoble, France
| | - Yohann Couté
- University Grenoble Alpes, CEA, INSERM, UA13 BGE, CNRS, CEA, FranceGrenoble
| | - Katy Jeannot
- UMR6249 Chrono-Environnement, UFR Santé, University of Franche-Comté, Besançon, France
- French National Reference Center for Antibiotic Resistance, Besançon, France
- Department of Bacteriology, Teaching Hospital of Besançon, Besançon, France
| | - Ina Attrée
- Team Bacterial Pathogenesis and Cellular Responses, University Grenoble Alpes, IBS, UMR5075, Grenoble, France
| |
Collapse
|
2
|
Woods H, Leman JK, Meiler J. Modeling membrane geometries implicitly in Rosetta. Protein Sci 2024; 33:e4908. [PMID: 38358133 PMCID: PMC10868433 DOI: 10.1002/pro.4908] [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: 08/25/2023] [Revised: 01/05/2024] [Accepted: 01/08/2024] [Indexed: 02/16/2024]
Abstract
Interactions between membrane proteins (MPs) and lipid bilayers are critical for many cellular functions. In the Rosetta molecular modeling suite, the implicit membrane energy function is based on a "slab" model, which represent the membrane as a flat bilayer. However, in nature membranes often have a curvature that is important for function and/or stability. Even more prevalent, in structural biology research MPs are reconstituted in model membrane systems such as micelles, bicelles, nanodiscs, or liposomes. Thus, we have modified the existing membrane energy potentials within the RosettaMP framework to allow users to model MPs in different membrane geometries. We show that these modifications can be utilized in core applications within Rosetta such as structure refinement, protein-protein docking, and protein design. For MP structures found in curved membranes, refining these structures in curved, implicit membranes produces higher quality models with structures closer to experimentally determined structures. For MP systems embedded in multiple membranes, representing both membranes results in more favorable scores compared to only representing one of the membranes. Modeling MPs in geometries mimicking the membrane model system used in structure determination can improve model quality and model discrimination.
Collapse
Affiliation(s)
- Hope Woods
- Center of Structural Biology, Vanderbilt UniversityNashvilleTennesseeUSA
- Chemical and Physical Biology ProgramVanderbilt UniversityNashvilleTennesseeUSA
| | | | - Jens Meiler
- Center of Structural Biology, Vanderbilt UniversityNashvilleTennesseeUSA
- Department of ChemistryVanderbilt UniversityNashvilleTennesseeUSA
- Institute for Drug Discovery, Leipzig University Medical SchoolLeipzigGermany
| |
Collapse
|
3
|
Evolution of conformation and thermal properties of bovine hides collagen in the sodium sulphide solution. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
4
|
Yılmaz İ, Korkmaz F. Investigations of pH-dependent dynamic properties of OmpG-16SL, an outer membrane protein G mutant by ATR-FTIR spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA. PROTEINS AND PROTEOMICS 2022; 1870:140780. [PMID: 35405324 DOI: 10.1016/j.bbapap.2022.140780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 04/03/2022] [Accepted: 04/05/2022] [Indexed: 06/14/2023]
Abstract
In this paper, the dynamic properties of outer membrane protein G mutant (OmpG-16SL) are investigated with ATR-FTIR spectroscopy. While OmpG-WT has 14 β-strands in its structure, the mutant is designed to have 16 β-strands with the intention of creating an enlarged pore. Loop L6 is elongated by introducing six residues, two of which are negatively charged. The solvent accessibility of the OmpG-16SL mutant is compared with WT and a previously reported mutant OmpG-16S by tracking the 1H/2H exchange kinetics in acidic and neutral buffer conditions. The exchange kinetics and dynamics in the fast and slow exchange phases are separately investigated using the 2DCOS technique, which enables the tracking of the structural changes at each phase of the exchange process. The results suggest that the mutant OmpG-16SL is equally exposed to buffer in both acidic and neutral pH conditions. Additionally, the time range in the fast phase is very short - one-tenth of that for WT - and most of the exchange is completed in this phase. This fast exchange within minutes is also indicative of the presence of highly flexible and/or unstructured regions. In all, the fast exchange rates independent of the buffer pH justify the assumption that there is an altered interaction among the charged residues, which leads to a steadily-open pore. The role of the side-chain interactions within the pore and between the loops involving the loop L6 is also discussed.
Collapse
Affiliation(s)
- İrem Yılmaz
- Physics Unit, Biophysics Laboratory, Atilim University, 06836 Ankara, Turkey
| | - Filiz Korkmaz
- Physics Unit, Biophysics Laboratory, Atilim University, 06836 Ankara, Turkey.
| |
Collapse
|
5
|
Li MF, Jia BB, Sun YY, Sun L. The Translocation and Assembly Module (TAM) of Edwardsiella tarda Is Essential for Stress Resistance and Host Infection. Front Microbiol 2020; 11:1743. [PMID: 32793174 PMCID: PMC7393178 DOI: 10.3389/fmicb.2020.01743] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 07/03/2020] [Indexed: 11/28/2022] Open
Abstract
Translocation and assembly module (TAM) is a protein channel known to mediate the secretion of virulence factors during pathogen infection. Edwardsiella tarda is a Gram-negative bacterium that is pathogenic to a wide range of farmed fish and other hosts including humans. In this study, we examined the function of the two components of the TAM, TamA and TamB, of E. tarda (named tamAEt and tamBEt, respectively). TamAEt was found to localize on the surface of E. tarda and be recognizable by TamAEt antibody. Compared to the wild type, the tamA and tamB knockouts, TX01ΔtamA and TX01ΔtamB, respectively, were significantly reduced in motility, flagella formation, invasion into host cells, intracellular replication, dissemination in host tissues, and inducing host mortality. The lost virulence capacities of TX01ΔtamA and TX01ΔtamB were restored by complementation with the tamAEt and tamBEt genes, respectively. Furthermore, TX01ΔtamA and TX01ΔtamB were significantly impaired in the ability to survive under low pH and oxidizing conditions, and were unable to maintain their internal pH balance and cellular structures in acidic environments, which led to increased susceptibility to lysozyme destruction. Taken together, these results indicate that TamAEt and TamBEt are essential for the virulence of E. tarda and required for E. tarda to survive under stress conditions.
Collapse
Affiliation(s)
- Mo-Fei Li
- CAS Key Laboratory of Experimental Marine Biology, CAS Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China
| | - Bei-Bei Jia
- CAS Key Laboratory of Experimental Marine Biology, CAS Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yuan-Yuan Sun
- CAS Key Laboratory of Experimental Marine Biology, CAS Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China
| | - Li Sun
- CAS Key Laboratory of Experimental Marine Biology, CAS Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, China
| |
Collapse
|
6
|
Pham B, Eron SJ, Hill ME, Li X, Fahie MA, Hardy JA, Chen M. A Nanopore Approach for Analysis of Caspase-7 Activity in Cell Lysates. Biophys J 2019; 117:844-855. [PMID: 31427065 PMCID: PMC6731459 DOI: 10.1016/j.bpj.2019.07.045] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 07/02/2019] [Accepted: 07/24/2019] [Indexed: 12/21/2022] Open
Abstract
Caspases are an important protease family that coordinate inflammation and programmed cell death. Two closely related caspases, caspase-3 and caspase-7, exhibit largely overlapping substrate specificities. Assessing their proteolytic activities individually has therefore proven extremely challenging. Here, we constructed an outer membrane protein G (OmpG) nanopore with a caspase substrate sequence DEVDG grafted into one of the OmpG loops. Cleavage of the substrate sequence in the nanopore by caspase-7 generated a characteristic signal in the current recording of the OmpG nanopore that allowed the determination of the activity of caspase-7 in Escherichia coli cell lysates. Our approach may provide a framework for the activity-based profiling of proteases that share highly similar substrate specificity spectrums.
Collapse
Affiliation(s)
- Bach Pham
- Department of Chemistry, University of Massachusetts Amherst, Amherst, Massachusetts
| | - Scott J Eron
- Department of Chemistry, University of Massachusetts Amherst, Amherst, Massachusetts
| | - Maureen E Hill
- Department of Chemistry, University of Massachusetts Amherst, Amherst, Massachusetts
| | - Xin Li
- Department of Chemistry, University of Massachusetts Amherst, Amherst, Massachusetts
| | - Monifa A Fahie
- Molecular and Cellular Biology Program, University of Massachusetts Amherst, Amherst, Massachusetts
| | - Jeanne A Hardy
- Department of Chemistry, University of Massachusetts Amherst, Amherst, Massachusetts; Molecular and Cellular Biology Program, University of Massachusetts Amherst, Amherst, Massachusetts
| | - Min Chen
- Department of Chemistry, University of Massachusetts Amherst, Amherst, Massachusetts; Molecular and Cellular Biology Program, University of Massachusetts Amherst, Amherst, Massachusetts.
| |
Collapse
|
7
|
Schmitt C, Bafna JA, Schmid B, Klingl S, Baier S, Hemmis B, Wagner R, Winterhalter M, Voll LM. Manipulation of charge distribution in the arginine and glutamate clusters of the OmpG pore alters sugar specificity and ion selectivity. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:183021. [PMID: 31306626 DOI: 10.1016/j.bbamem.2019.07.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Revised: 07/02/2019] [Accepted: 07/09/2019] [Indexed: 01/08/2023]
Abstract
OmpG is a general diffusion pore in the E. coli outer membrane with a molecular architecture comprising a 14-stranded β-barrel scaffold and unique structural features. In contrast to other non-specific porins, OmpG lacks a central constriction zone and has an exceptionally wide pore diameter of about 13 Å. The equatorial plane of OmpG harbors an annulus of four alternating basic and acidic patches whose function is only poorly characterized. We have investigated the role of charge distribution for ion selectivity and sugar transport with the help of OmpG variants mutated in the annulus. Substituting the glutamate residues of the annulus for histidines or alanines led to a strong reduction in cation selectivity. Replacement of the glutamates in the annulus by histidine residues also disfavored the passage of pentoses and hexoses relative to disaccharides. Our results demonstrate that despite the wide pore diameter, an annulus only consisting of two opposing basic patches confers reduced cation and monosaccharide transport compared to OmpG wild type. Furthermore, randomization of charged residues in the annulus had the potential to abolish pH-dependency of sugar transport. Our results indicate that E15, E31, R92, R111 and R211 in the annulus form electrostatic interactions with R228, E229 and D232 in loop L6 that influence pH-dependency of sugar transport.
Collapse
Affiliation(s)
- Christine Schmitt
- Division of Biochemistry and Applied Protein Center Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany; Department Biology, Division of Plant Physiology, Philipps-University Marburg, D-35043 Marburg, Germany.
| | - Jayesh Arun Bafna
- Department of Life Sciences and Chemistry, Jacobs University Bremen, D-28719 Bremen, Germany.
| | - Benedikt Schmid
- Division of Biotechnology and Applied Protein Center Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany.
| | - Stefan Klingl
- Division of Biotechnology and Applied Protein Center Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany.
| | - Steffen Baier
- Division of Biochemistry and Applied Protein Center Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany
| | - Birgit Hemmis
- Department of Biology and Chemistry, University of Osnabrück, D-49069 Osnabrück, Germany
| | - Richard Wagner
- Department of Life Sciences and Chemistry, Jacobs University Bremen, D-28719 Bremen, Germany; Department of Biology and Chemistry, University of Osnabrück, D-49069 Osnabrück, Germany.
| | - Mathias Winterhalter
- Department of Life Sciences and Chemistry, Jacobs University Bremen, D-28719 Bremen, Germany.
| | - Lars M Voll
- Division of Biochemistry and Applied Protein Center Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany; Department Biology, Division of Plant Physiology, Philipps-University Marburg, D-35043 Marburg, Germany.
| |
Collapse
|
8
|
Yılmaz İ, Yıldız Ö, Korkmaz F. Structural properties of an engineered outer membrane protein G mutant, OmpG-16SL, investigated with infrared spectroscopy. J Biomol Struct Dyn 2019; 38:2104-2115. [PMID: 31157607 DOI: 10.1080/07391102.2019.1624617] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The structural and functional differences between wild type (WT) outer membrane protein G and its two mutants are investigated with Fourier transform infrared spectroscopy. Both mutants have a long extension to the primary sequence to increase the number of β-strands from 14 (wild type) to 16 in an attempt to enlarge the pore diameter. The comparison among proteins is made in terms of pH-dependent conformational changes and thermal stability. Results show that all proteins respond to pH change but at different degrees. At acidic environment, all proteins contain the same number of residues participated in β-sheet structure. However, at neutral pH, the mutants have less ordered structure compared to WT porin. Thermal stability tests show that mutants differ significantly from WT porin at neutral pH. Although the transition temperature is directly proportional with the amount of β-sheet content, the changes in the pre-transition phase that pave the way to structural breakdown are shown to involve interactions among charged residues by two-dimensional correlation spectroscopy analysis. Results of the analysis show that side chain interactions play an active role under increasing temperature. Both mutants have more unordered secondary structure but they respond to pH change in tertiary structure level. Findings of this study provided deeper insight on the active players in structural stability of the WT porin.Communicated by Ramaswamy H. Sarma [Formula: see text].
Collapse
Affiliation(s)
- İrem Yılmaz
- Department of Physics, Middle East Technical University, Ankara, Turkey
| | - Özkan Yıldız
- Department of Structural Biology, Max Planck Institute for Biophysics, Frankfurt am Main, Germany
| | - Filiz Korkmaz
- Physics Unit, Biophysics Laboratory, Atilim University, Ankara, Turkey
| |
Collapse
|
9
|
Gunasekera B, Abou Diwan C, Altawallbeh G, Kalil H, Maher S, Xu S, Bayachou M. Functional Layer-by-Layer Thin Films of Inducible Nitric Oxide (NO) Synthase Oxygenase and Polyethylenimine: Modulation of Enzyme Loading and NO-Release Activity. ACS APPLIED MATERIALS & INTERFACES 2018; 10:7745-7755. [PMID: 29359547 DOI: 10.1021/acsami.7b17575] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Nitric oxide (NO) release counteracts platelet aggregation and prevents the thrombosis cascade in the inner walls of blood vessels. NO-release coatings also prevent thrombus formation on the surface of blood-contacting medical devices. Our previous work has shown that inducible nitric oxide synthase (iNOS) films release NO fluxes upon enzymatic conversion of the substrate l-arginine. In this work, we report on the modulation of enzyme loading in layer-by-layer (LbL) thin films of inducible nitric oxide synthase oxygenase (iNOSoxy) on polyethylenimine (PEI). The layer of iNOSoxy is electrostatically adsorbed onto the PEI layer. The pH of the iNOSoxy solution affects the amount of enzyme adsorbed. The overall negative surface charge of iNOSoxy in solution depends on the pH and hence determines the density of adsorbed protein on the positively charged PEI layer. We used buffered iNOSoxy solutions adjusted to pHs 8.6 and 7.0, while saline PEI solution was used at pH 7.0. Atomic force microscopy imaging of the outermost layer shows higher protein adsorption with iNOSoxy at pH 8.6 than with a solution of iNOSoxy at pH 7.0. Graphite electrodes with PEI/iNOSoxy films show higher catalytic currents for nitric oxide reduction mediated by iNOSoxy. The higher enzyme loading translates into higher NO flux when the enzyme-modified surface is exposed to a solution containing the substrate and a source of electrons. Spectrophotometric assays showed higher NO fluxes with iNOSoxy/PEI films built at pH 8.6 than with films built at pH 7.0. Fourier transform infrared analysis of iNOSoxy adsorbed on PEI at pH 8.6 and 7.0 shows structural differences of iNOSoxy in films, which explains the observed changes in enzymatic activity. Our findings show that pH provides a strategy to optimize the NOS loading and enzyme activity in NOS-based LbL thin films, which enables improved NO release with minimum layers of PEI/NOS.
Collapse
Affiliation(s)
- Bhagya Gunasekera
- Department of Chemistry , Cleveland State University , 2399 Euclid Avenue SR 397 , Cleveland , Ohio 44120 , United States
| | - Charbel Abou Diwan
- Department of Chemistry , Cleveland State University , 2399 Euclid Avenue SR 397 , Cleveland , Ohio 44120 , United States
| | - Ghaith Altawallbeh
- Department of Chemistry , Cleveland State University , 2399 Euclid Avenue SR 397 , Cleveland , Ohio 44120 , United States
| | - Haitham Kalil
- Department of Chemistry , Cleveland State University , 2399 Euclid Avenue SR 397 , Cleveland , Ohio 44120 , United States
| | - Shaimaa Maher
- Department of Chemistry , Cleveland State University , 2399 Euclid Avenue SR 397 , Cleveland , Ohio 44120 , United States
| | - Song Xu
- Keysight Technologies , 1400 Foutaingrove Parkway , Santa Rosa 95403 , California , United States
| | - Mekki Bayachou
- Department of Chemistry , Cleveland State University , 2399 Euclid Avenue SR 397 , Cleveland , Ohio 44120 , United States
- Department of Pathobiology , Lerner Research Institute , The Cleveland Clinic , Cleveland , Ohio 44106 , United States
| |
Collapse
|
10
|
Perez-Rathke A, Fahie MA, Chisholm C, Liang J, Chen M. Mechanism of OmpG pH-Dependent Gating from Loop Ensemble and Single Channel Studies. J Am Chem Soc 2018; 140:1105-1115. [PMID: 29262680 DOI: 10.1021/jacs.7b11979] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Outer membrane protein G (OmpG) from Escherichia coli has exhibited pH-dependent gating that can be employed by bacteria to alter the permeability of their outer membranes in response to environmental changes. We developed a computational model, Protein Topology of Zoetic Loops (Pretzel), to investigate the roles of OmpG extracellular loops implicated in gating. The key interactions predicted by our model were verified by single-channel recording data. Our results indicate that the gating equilibrium is primarily controlled by an electrostatic interaction network formed between the gating loop and charged residues in the lumen. The results shed light on the mechanism of OmpG gating and will provide a fundamental basis for the engineering of OmpG as a nanopore sensor. Our computational Pretzel model could be applied to other outer membrane proteins that contain intricate dynamic loops that are functionally important.
Collapse
Affiliation(s)
- Alan Perez-Rathke
- Department of Bioengineering, University of Illinois at Chicago , Chicago, Illinois 60607, United States
| | | | | | - Jie Liang
- Department of Bioengineering, University of Illinois at Chicago , Chicago, Illinois 60607, United States
| | | |
Collapse
|
11
|
Abstract
β-barrel proteins mediate nutrient uptake in bacteria and serve vital functions in cell signaling and adhesion. For the 14-strand outer membrane protein G of Escherichia coli, opening and closing is pH-dependent. Different roles of the extracellular loops in this process were proposed, and X-ray and solution NMR studies were divergent. Here, we report the structure of outer membrane protein G investigated in bilayers of E. coli lipid extracts by magic-angle-spinning NMR. In total, 1847 inter-residue 1H–1H and 13C–13C distance restraints, 256 torsion angles, but no hydrogen bond restraints are used to calculate the structure. The length of β-strands is found to vary beyond the membrane boundary, with strands 6–8 being the longest and the extracellular loops 3 and 4 well ordered. The site of barrel closure at strands 1 and 14 is more disordered than most remaining strands, with the flexibility decreasing toward loops 3 and 4. Loop 4 presents a well-defined helix. Porins, like OmpG, are embedded in the outer membrane of bacteria and facilitate uptake and secretion of nutrients and ions. Here the authors present a protocol for solid state NMR structure determination of proteins larger than 25 kDa and use it to structurally characterize membrane embedded OmpG.
Collapse
|
12
|
Koehler Leman J, D'Avino AR, Bhatnagar Y, Gray JJ. Comparison of NMR and crystal structures of membrane proteins and computational refinement to improve model quality. Proteins 2017; 86:57-74. [PMID: 29044728 DOI: 10.1002/prot.25402] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 09/27/2017] [Accepted: 10/11/2017] [Indexed: 12/29/2022]
Abstract
Membrane proteins are challenging to study and restraints for structure determination are typically sparse or of low resolution because the membrane environment that surrounds them leads to a variety of experimental challenges. When membrane protein structures are determined by different techniques in different environments, a natural question is "which structure is most biologically relevant?" Towards answering this question, we compiled a dataset of membrane proteins with known structures determined by both solution NMR and X-ray crystallography. By investigating differences between the structures, we found that RMSDs between crystal and NMR structures are below 5 Å in the membrane region, NMR ensembles have a higher convergence in the membrane region, crystal structures typically have a straighter transmembrane region, have higher stereo-chemical correctness, and are more tightly packed. After quantifying these differences, we used high-resolution refinement of the NMR structures to mitigate them, which paves the way for identifying and improving the structural quality of membrane proteins.
Collapse
Affiliation(s)
- Julia Koehler Leman
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland.,Center for Computational Biology, Flatiron Institute, Simons Foundation, New York, New York
| | - Andrew R D'Avino
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland.,Department of Biology, Johns Hopkins University, Baltimore, Maryland
| | - Yash Bhatnagar
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland
| | - Jeffrey J Gray
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland
| |
Collapse
|
13
|
Shubin VV, Terekhova IV, Bolychevtseva YV, El-Mohsnawy E, Rögner M, Mäntele W, Kopczak MJ, Džafić E. Thermostability of photosystem I trimers and monomers from the cyanobacterium Thermosynechococcus elongatus. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2017; 179:17-22. [PMID: 28213141 DOI: 10.1016/j.saa.2017.02.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 01/30/2017] [Accepted: 02/04/2017] [Indexed: 06/06/2023]
Abstract
The performance of solar energy conversion into alternative energy sources in artificial systems highly depends on the thermostability of photosystem I (PSI) complexes Terasaki et al. (2007), Iwuchukwu et al. (2010), Kothe et al. (2013) . To assess the thermostability of PSI complexes from the thermophilic cyanobacterium Thermosynechococcus elongatus heating induced perturbations on the level of secondary structure of the proteins were studied. Changes were monitored by Fourier transform infrared (FT-IR) spectra in the mid-IR region upon slow heating (1°C per minute) of samples in D2O phosphate buffer (pD 7.4) from 20°C to 100°C. These spectra showed distinct changes in the Amide I region of PSI complexes as a function of the rising temperature. Absorbance at the Amide I maximum of PSI monomers (centered around 1653cm-1), gradually dropped in two temperature intervals, i.e. 60-75 and 80-90°C. In contrast, absorbance at the Amide I maximum of PSI trimers (around 1656cm-1) dropped only in one temperature interval 80-95°C. The thermal profile of the spectral shift of α-helices bands in the region 1656-1642cm-1 confirms the same two temperature intervals for PSI monomers and only one interval for trimers. Apparently, the observed absorbance changes at the Amide I maximum during heating of PSI monomers and trimers are caused by deformation and unfolding of α-helices. The absence of absorbance changes in the interval of 20-65°C in PSI trimers is probably caused by a greater stability of protein secondary structure as compared to that in monomers. Upon heating above 80°C a large part of α-helices both in trimers and monomers converts to unordered and aggregated structures. Spectral changes of PSI trimers and monomers heated up to 100°C are irreversible due to protein denaturation and non-specific aggregation of complexes leading to new absorption bands at 1618-1620cm-1. We propose that monomers shield the denaturation sensitive sides at the monomer/monomer interface within a trimer, making the oligomeric structure more stable against thermal stress.
Collapse
Affiliation(s)
- Vladimir V Shubin
- Baсh Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, 33, bld.2, Leninsky Ave., Moscow 119071, Russia
| | - Irina V Terekhova
- Baсh Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, 33, bld.2, Leninsky Ave., Moscow 119071, Russia.
| | - Yulia V Bolychevtseva
- Baсh Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, 33, bld.2, Leninsky Ave., Moscow 119071, Russia
| | - Eithar El-Mohsnawy
- Biochemie der Pflanzen, Ruhr Universität Bochum, 44780 Bochum, Germany; Botany Department, Faculty of Science, Kafrelsheikh University, 33511 Kafrelsheikh, Egypt
| | - Matthias Rögner
- Biochemie der Pflanzen, Ruhr Universität Bochum, 44780 Bochum, Germany
| | - Werner Mäntele
- Institut für Biophysik, J.W. Goethe Universität Frankfurt, 60438 Frankfurt, Germany
| | - Marta J Kopczak
- Biochemie der Pflanzen, Ruhr Universität Bochum, 44780 Bochum, Germany
| | - Enela Džafić
- Institut für Biophysik, J.W. Goethe Universität Frankfurt, 60438 Frankfurt, Germany
| |
Collapse
|
14
|
IR-spectroscopic characterization of an elongated OmpG mutant. Arch Biochem Biophys 2015; 576:73-9. [DOI: 10.1016/j.abb.2015.04.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 04/10/2015] [Accepted: 04/27/2015] [Indexed: 11/22/2022]
|
15
|
Purification, Refolding, and Crystallization of the Outer Membrane Protein OmpG from Escherichia coli. Methods Enzymol 2015. [PMID: 25950964 DOI: 10.1016/bs.mie.2015.01.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
OmpG is a pore-forming protein from E. coli outer membranes. Unlike the classical outer membrane porins, which are trimers, the OmpG channel is a monomeric β-barrel made of 14 antiparallel β-strands with short periplasmic turns and longer extracellular loops. The channel activity of OmpG is pH dependent and the channel is gated by the extracellular loop L6. At neutral/high pH, the channel is open and permeable for substrate molecules with a size up to 900 Da. At acidic pH, loop L6 folds across the channel and blocks the pore. The channel blockage at acidic pH appears to be triggered by the protonation of a histidine pair on neighboring β-strands, which repel one another, resulting in the rearrangement of loop L6 and channel closure. OmpG was purified by refolding from inclusion bodies and crystallized in two and three dimensions. Crystallization and analysis by electron microscopy and X-ray crystallography revealed the fundamental mechanisms essential for the channel activity.
Collapse
|
16
|
Grosse W, Psakis G, Mertins B, Reiss P, Windisch D, Brademann F, Bürck J, Ulrich A, Koert U, Essen LO. Structure-based engineering of a minimal porin reveals loop-independent channel closure. Biochemistry 2014; 53:4826-38. [PMID: 24988371 DOI: 10.1021/bi500660q] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Porins, like outer membrane protein G (OmpG) of Escherichia coli, are ideal templates among ion channels for protein and chemical engineering because of their robustness and simple architecture. OmpG shows fast transitions between open and closed states, which were attributed to loop 6 (L6). As flickering limits single-channel-based applications, we pruned L6 by either 8 or 12 amino acids. While the open probabilities of both L6 variants resemble that of native OmpG, their gating frequencies were reduced by 63 and 81%, respectively. Using the 3.2 Å structure of the shorter L6 variant in the open state, we engineered a minimal porin (220 amino acids), where all remaining extramembranous loops were truncated. Unexpectedly, this minimized porin still exhibited gating, but it was 5-fold less frequent than in OmpG. The residual gating of the minimal pore is hence independent of L6 rearrangements and involves narrowing of the ion conductance pathway most probably driven by global stretching-flexing deformations of the membrane-embedded β-barrel.
Collapse
Affiliation(s)
- Wolfgang Grosse
- Department of Chemistry, Philipps-University Marburg , Hans-Meerwein-Straße, 35032 Marburg, Germany
| | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Offenbacher AR, Watson RA, Pagba CV, Barry BA. Redox-dependent structural coupling between the α2 and β2 subunits in E. coli ribonucleotide reductase. J Phys Chem B 2014; 118:2993-3004. [PMID: 24606240 DOI: 10.1021/jp501121d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Ribonucleotide reductase (RNR) catalyzes the production of deoxyribonucleotides in all cells. In E. coli class Ia RNR, a transient α2β2 complex forms when a ribonucleotide substrate, such as CDP, binds to the α2 subunit. A tyrosyl radical (Y122O•)-diferric cofactor in β2 initiates substrate reduction in α2 via a long-distance, proton-coupled electron transfer (PCET) process. Here, we use reaction-induced FT-IR spectroscopy to describe the α2β2 structural landscapes, which are associated with dATP and hydroxyurea (HU) inhibition. Spectra were acquired after mixing E. coli α2 and β2 with a substrate, CDP, and the allosteric effector, ATP. Isotopic chimeras, (13)Cα2β2 and α2(13)Cβ2, were used to define subunit-specific structural changes. Mixing of α2 and β2 under turnover conditions yielded amide I (C═O) and II (CN/NH) bands, derived from each subunit. The addition of the inhibitor, dATP, resulted in a decreased contribution from amide I bands, attributable to β strands and disordered structures. Significantly, HU-mediated reduction of Y122O• was associated with structural changes in α2, as well as β2. To define the spectral contributions of Y122O•/Y122OH in the quaternary complex, (2)H4 labeling of β2 tyrosines and HU editing were performed. The bands of Y122O•, Y122OH, and D84, a unidentate ligand to the diferric cluster, previously identified in isolated β2, were observed in the α2β2 complex. These spectra also provide evidence for a conformational rearrangement at an additional β2 tyrosine(s), Yx, in the α2β2/CDP/ATP complex. This study illustrates the utility of reaction-induced FT-IR spectroscopy in the study of complex enzymes.
Collapse
Affiliation(s)
- Adam R Offenbacher
- School of Chemistry and Biochemistry and the Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| | | | | | | |
Collapse
|
18
|
Zhuang T, Chisholm C, Chen M, Tamm LK. NMR-based conformational ensembles explain pH-gated opening and closing of OmpG channel. J Am Chem Soc 2013; 135:15101-13. [PMID: 24020969 DOI: 10.1021/ja408206e] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The outer membrane protein G (OmpG) is a monomeric 33 kDa 14-stranded β-barrel membrane protein functioning as a nonspecific porin for the uptake of oligosaccharides in Escherichia coli. Two different crystal structures of OmpG obtained at different values of pH suggest a pH-gated pore opening mechanism. In these structures, extracellular loop 6 extends away from the barrel wall at neutral pH but is folded back into the pore lumen at low pH, blocking transport through the pore. Loop 6 was invisible in a previously published solution NMR structure of OmpG in n-dodecylphosphocholine micelles, presumably due to conformational exchange on an intermediate NMR time scale. Here we present an NMR paramagnetic relaxation enhancement (PRE)-based approach to visualize the conformational dynamics of loop 6 and to calculate conformational ensembles that explain the pH-gated opening and closing of the OmpG channel. The different loop conformers detected by the PRE ensemble calculations were validated by disulfide cross-linking of strategically engineered cysteines and electrophysiological single channel recordings. The results indicate a more dynamically regulated channel opening and closing than previously thought and reveal additional membrane-associated conformational ensembles at pH 6.3 and 7.0. We anticipate this approach to be generally applicable to detect and characterize functionally important conformational ensembles of membrane proteins.
Collapse
Affiliation(s)
- Tiandi Zhuang
- Department of Molecular Physiology and Biological Physics and Center for Membrane Biology, University of Virginia , Charlottesville, Virginia 22903, United States
| | | | | | | |
Collapse
|
19
|
Nakayama M, Shimatani K, Ozawa T, Shigemune N, Tsugukuni T, Tomiyama D, Kurahachi M, Nonaka A, Miyamoto T. A study of the antibacterial mechanism of catechins: Isolation and identification of Escherichia coli cell surface proteins that interact with epigallocatechin gallate. Food Control 2013. [DOI: 10.1016/j.foodcont.2013.03.016] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
|
20
|
Yu M, Sun P, He Y, Xiao L, Sun D, Zhang L, Tian C. Mutation of the critical pH-gating residues histidine 231 to glutamate increase open probability of outer membrane protein G in planar lipid bilayer. Protein Cell 2013; 4:803-6. [PMID: 24018649 DOI: 10.1007/s13238-013-3070-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Affiliation(s)
- Mu Yu
- High Magnetic Field Laboratory, Chinese Academic of Sciences, Hefei, 230031, China
| | | | | | | | | | | | | |
Collapse
|
21
|
Korkmaz F, Ressl S, Ziegler C, Mäntele W. K+-induced conformational changes in the trimeric betaine transporter BetP monitored by ATR-FTIR spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:1181-91. [DOI: 10.1016/j.bbamem.2013.01.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Revised: 12/10/2012] [Accepted: 01/08/2013] [Indexed: 11/28/2022]
|
22
|
Nanda V, Hsieh D, Davis A. Prediction and design of outer membrane protein-protein interactions. Methods Mol Biol 2013; 1063:183-96. [PMID: 23975778 DOI: 10.1007/978-1-62703-583-5_10] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Protein-protein interactions (PPI) play central roles in biological processes, motivating us to understand the structural basis underlying affinity and specificity. In this chapter, we focus on biochemical and computational design strategies of assessing and detecting PPIs of β-barrel outer membrane proteins (OMPs). A few case studies are presented highlighting biochemical techniques used to dissect the energetics of oligomerization and determine amino acids forming the key interactions of the PPI sites. Current computational strategies for detecting/predicting PPIs are introduced, and examples of computational and rational engineering strategies applied to OMPs are presented.
Collapse
Affiliation(s)
- Vikas Nanda
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School-UMDNJ, Piscataway, NJ, USA
| | | | | |
Collapse
|
23
|
Korkmaz F, Köster S, Yildiz O, Mäntele W. In situ opening/closing of OmpG from E. coli and the splitting of β-sheet signals in ATR-FTIR spectroscopy. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2012; 91:395-401. [PMID: 22402479 DOI: 10.1016/j.saa.2012.01.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Revised: 01/04/2012] [Accepted: 01/16/2012] [Indexed: 05/31/2023]
Abstract
The pH dependent opening and closure of Escherichia coli OmpG is driven by the formation and breaking of hydrogen bridges in β-strands S11-S13. We have investigated the in situ secondary structural changes of OmpG with ATR-FTIR difference spectroscopy in order to detect the signals associated with the newly established interactions. Curve-fitting of OmpG in two pH conditions revealed the splitting and shifting of β-sheet signals upon opening of the channel. Besides secondary structure changes, there are also amino acid side chain signals that play active role in opening/closing of the channel. An interaction among positively charged arginines and negatively charged aspartic and glutamic acid residues is suggested upon closure of the channel while this interaction is abolished when the channel opens at higher pH.
Collapse
Affiliation(s)
- Filiz Korkmaz
- Atilim University, Physics Unit, Biophysics Laboratory, Kizilcasar Mah., 06836 Ankara, Turkey.
| | | | | | | |
Collapse
|
24
|
Abstract
Membranes form natural barriers that need to be permeable to diverse matter like ions and substrates. This permeability is controlled by ion-channel proteins, which have attracted great interest for pharmaceutical applications. Ion-channel engineering (ICE) modifies biological ion channels by chemical/biological synthetis means. The goal is to obtain ion channels with modified or novel functionality. Three functional strategies exist. The first is the manipulation of the wider pores with robust β-barrel structures, such as those of α-hemolysin and porins. The second engineering approach focuses on the modification of narrow (mostly α-helical) pores to understand selectivity and modes of action. A third functional approach addresses channel gating by (photo)triggering the biological receptor that controls the channel. Several synthetis strategies have been developed and successfully utilized for the synthetic modification of biological ion-channels: the S-alkylation of specifically introduced Cys, protein semisynthesis by native chemical ligation, protein semisynthesis by protein trans-splicing, as well as nonsense-suppression methods. Structural studies (X-ray crystallography, NMR spectroscopy) are necessary to support the functional studies and to afford predictable engineering. The reprogramming and re-engineering of channels can be used for sensing applications, treatment of channelopathies, chemical neurobiology, and providing novel lead compounds for targeting ion channels.
Collapse
Affiliation(s)
- Wolfgang Grosse
- Fachbereich Chemie, Philipps-Universität Marburg, Marburg, Germany
| | | | | |
Collapse
|