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Deryusheva EI, Machulin AV, Galzitskaya OV. Structural, Functional, and Evolutionary Characteristics of Proteins with Repeats. Mol Biol 2021. [DOI: 10.1134/s0026893321040038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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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.
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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.
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Chumjan W, Winterhalter M, Schulte A, Benz R, Suginta W. Chitoporin from the Marine Bacterium Vibrio harveyi: PROBING THE ESSENTIAL ROLES OF TRP136 AT THE SURFACE OF THE CONSTRICTION ZONE. J Biol Chem 2015; 290:19184-96. [PMID: 26082491 DOI: 10.1074/jbc.m115.660530] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Indexed: 11/06/2022] Open
Abstract
VhChiP is a sugar-specific porin present in the outer membrane of the marine bacterium Vibrio harveyi. VhChiP is responsible for the uptake of chitin oligosaccharides, with particular selectivity for chitohexaose. In this study, we employed electrophysiological and biochemical approaches to demonstrate that Trp(136), located at the mouth of the VhChiP pore, plays an essential role in controlling the channel's ion conductivity, chitin affinity, and permeability. Kinetic analysis of sugar translocation obtained from single channel recordings indicated that the Trp(136) mutations W136A, W136D, W136R, and W136F considerably reduce the binding affinity of the protein channel for its best substrate, chitohexaose. Liposome swelling assays confirmed that the Trp(136) mutations decreased the rate of bulk chitohexaose permeation through the VhChiP channel. Notably, all of the mutants show increases in the off-rate for chitohexaose of up to 20-fold compared with that of the native channel. Furthermore, the cation/anion permeability ratio Pc/Pa is decreased in the W136R mutant and increased in the W136D mutant. This demonstrates that the negatively charged surface at the interior of the protein lumen preferentially attracts cationic species, leading to the cation selectivity of this trimeric channel.
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Affiliation(s)
- Watcharin Chumjan
- From the Biochemistry-Electrochemistry Research Unit, the School of Biochemistry, and
| | - Mathias Winterhalter
- the Department of Life Sciences and Chemistry, Jacobs University Bremen, D-28759 Bremen, Germany
| | - Albert Schulte
- From the Biochemistry-Electrochemistry Research Unit, the School of Chemistry, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand and
| | - Roland Benz
- the Department of Life Sciences and Chemistry, Jacobs University Bremen, D-28759 Bremen, Germany
| | - Wipa Suginta
- From the Biochemistry-Electrochemistry Research Unit, the School of Biochemistry, and
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Villinger S, Giller K, Bayrhuber M, Lange A, Griesinger C, Becker S, Zweckstetter M. Nucleotide interactions of the human voltage-dependent anion channel. J Biol Chem 2014; 289:13397-406. [PMID: 24668813 DOI: 10.1074/jbc.m113.524173] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The voltage-dependent anion channel (VDAC) mediates and gates the flux of metabolites and ions across the outer mitochondrial membrane and is a key player in cellular metabolism and apoptosis. Here we characterized the binding of nucleotides to human VDAC1 (hVDAC1) on a single-residue level using NMR spectroscopy and site-directed mutagenesis. We find that hVDAC1 possesses one major binding region for ATP, UTP, and GTP that partially overlaps with a previously determined NADH binding site. This nucleotide binding region is formed by the N-terminal α-helix, the linker connecting the helix to the first β-strand and adjacent barrel residues. hVDAC1 preferentially binds the charged forms of ATP, providing support for a mechanism of metabolite transport in which direct binding to the charged form exerts selectivity while at the same time permeation of the Mg(2+)-complexed ATP form is possible.
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Affiliation(s)
- Saskia Villinger
- From the Department of NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
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