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Structural basis for chitin acquisition by marine Vibrio species. Nat Commun 2018; 9:220. [PMID: 29335469 PMCID: PMC5768706 DOI: 10.1038/s41467-017-02523-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 12/07/2017] [Indexed: 11/18/2022] Open
Abstract
Chitin, an insoluble polymer of N-acetylglucosamine, is one of the most abundant biopolymers on Earth. By degrading chitin, chitinolytic bacteria such as Vibrio harveyi are critical for chitin recycling and maintenance of carbon and nitrogen cycles in the world’s oceans. A decisive step in chitin degradation is the uptake of chito-oligosaccharides by an outer membrane protein channel named chitoporin (ChiP). Here, we report X-ray crystal structures of ChiP from V. harveyi in the presence and absence of chito-oligosaccharides. Structures without bound sugar reveal a trimeric assembly with an unprecedented closing of the transport pore by the N-terminus of a neighboring subunit. Substrate binding ejects the pore plug to open the transport channel. Together with molecular dynamics simulations, electrophysiology and in vitro transport assays our data provide an explanation for the exceptional affinity of ChiP for chito-oligosaccharides and point to an important role of the N-terminal gate in substrate transport. Chitin degrading bacteria are important for marine ecosystems. Here the authors structurally and functionally characterize the Vibrio harveyi outer membrane diffusion channel chitoporin and give mechanistic insights into chito-oligosaccharide uptake.
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Jahangiri A, Rasooli I, Owlia P, Imani Fooladi AA, Salimian J. Highly conserved exposed immunogenic peptides of Omp34 against Acinetobacter baumannii: An innovative approach. J Microbiol Methods 2018; 144:79-85. [DOI: 10.1016/j.mimet.2017.11.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Revised: 11/06/2017] [Accepted: 11/09/2017] [Indexed: 11/16/2022]
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van Teeseling MCF, Benz R, de Almeida NM, Jetten MSM, Mesman RJ, van Niftrik L. Characterization of the first planctomycetal outer membrane protein identifies a channel in the outer membrane of the anammox bacterium Kuenenia stuttgartiensis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:767-776. [PMID: 29288627 DOI: 10.1016/j.bbamem.2017.12.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 11/30/2017] [Accepted: 12/25/2017] [Indexed: 01/27/2023]
Abstract
Planctomycetes are a bacterial phylum known for their complex intracellular compartmentalization. While most Planctomycetes have two compartments, the anaerobic ammonium oxidizing (anammox) bacteria contain three membrane-enclosed compartments. In contrast to a long-standing consensus, recent insights suggested the outermost Planctomycete membrane to be similar to a Gram-negative outer membrane (OM). One characteristic component that differentiates OMs from cytoplasmic membranes (CMs) is the presence of outer membrane proteins (OMPs) featuring a β-barrel structure that facilitates passage of molecules through the OM. Although proteomic and genomic evidence suggested the presence of OMPs in several Planctomycetes, no experimental verification existed of the pore-forming function and localization of these proteins in the outermost membrane of these exceptional microorganisms. Here, we show via lipid bilayer assays that at least two typical OMP-like channel-forming proteins are present in membrane preparations of the anammox bacterium Kuenenia stuttgartiensis. One of these channel-forming proteins, the highly abundant putative OMP Kustd1878, was purified to homogeneity. Analysis of the channel characteristics via lipid bilayer assays showed that Kustd1878 forms a moderately cation-selective channel with a high current noise and an average single-channel conductance of about 170-190pS in 1M KCl. Antibodies were raised against the purified protein and immunogold localization indicated Kustd1878 to be present in the outermost membrane. Therefore, this work clearly demonstrates the presence of OMPs in anammox Planctomycetes and thus firmly adds to the emerging view that Planctomycetes have a Gram-negative cell envelope.
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Affiliation(s)
- Muriel C F van Teeseling
- Department of Microbiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University, Nijmegen, The Netherlands.
| | - Roland Benz
- Department of Life Sciences and Chemistry, Jacobs University, Bremen, Germany
| | - Naomi M de Almeida
- Department of Microbiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University, Nijmegen, The Netherlands
| | - Mike S M Jetten
- Department of Microbiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University, Nijmegen, The Netherlands
| | - Rob J Mesman
- Department of Microbiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University, Nijmegen, The Netherlands
| | - Laura van Niftrik
- Department of Microbiology, Institute for Water and Wetland Research, Faculty of Science, Radboud University, Nijmegen, The Netherlands.
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54
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Tsirigos KD, Govindarajan S, Bassot C, Västermark Å, Lamb J, Shu N, Elofsson A. Topology of membrane proteins-predictions, limitations and variations. Curr Opin Struct Biol 2017; 50:9-17. [PMID: 29100082 DOI: 10.1016/j.sbi.2017.10.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 09/29/2017] [Accepted: 10/03/2017] [Indexed: 10/18/2022]
Abstract
Transmembrane proteins perform a variety of important biological functions necessary for the survival and growth of the cells. Membrane proteins are built up by transmembrane segments that span the lipid bilayer. The segments can either be in the form of hydrophobic alpha-helices or beta-sheets which create a barrel. A fundamental aspect of the structure of transmembrane proteins is the membrane topology, that is, the number of transmembrane segments, their position in the protein sequence and their orientation in the membrane. Along these lines, many predictive algorithms for the prediction of the topology of alpha-helical and beta-barrel transmembrane proteins exist. The newest algorithms obtain an accuracy close to 80% both for alpha-helical and beta-barrel transmembrane proteins. However, lately it has been shown that the simplified picture presented when describing a protein family by its topology is limited. To demonstrate this, we highlight examples where the topology is either not conserved in a protein superfamily or where the structure cannot be described solely by the topology of a protein. The prediction of these non-standard features from sequence alone was not successful until the recent revolutionary progress in 3D-structure prediction of proteins.
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Affiliation(s)
| | - Sudha Govindarajan
- Science for Life Laboratory, Stockholm University, SE-171 21 Solna, Sweden; Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Claudio Bassot
- Science for Life Laboratory, Stockholm University, SE-171 21 Solna, Sweden; Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Åke Västermark
- Science for Life Laboratory, Stockholm University, SE-171 21 Solna, Sweden; Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden; NITECH, Showa-Ku, Nagoya 466-8555 Japan
| | - John Lamb
- Science for Life Laboratory, Stockholm University, SE-171 21 Solna, Sweden; Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Nanjiang Shu
- Science for Life Laboratory, Stockholm University, SE-171 21 Solna, Sweden; Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden; National Bioinformatics Infrastructure, Sweden; Nordic e-Infrastructure Collaboration, Sweden
| | - Arne Elofsson
- Science for Life Laboratory, Stockholm University, SE-171 21 Solna, Sweden; Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden; Swedish e-Science Research Center (SeRC), Sweden.
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55
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Webb CT, Chandrapala D, Oslan SN, Bamert RS, Grinter RD, Dunstan RA, Gorrell RJ, Song J, Strugnell RA, Lithgow T, Kwok T. Reductive evolution in outer membrane protein biogenesis has not compromised cell surface complexity in Helicobacter pylori. Microbiologyopen 2017; 6. [PMID: 29055967 PMCID: PMC5727368 DOI: 10.1002/mbo3.513] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 05/19/2017] [Accepted: 05/25/2017] [Indexed: 12/18/2022] Open
Abstract
Helicobacter pylori is a gram‐negative bacterial pathogen that chronically inhabits the human stomach. To survive and maintain advantage, it has evolved unique host–pathogen interactions mediated by Helicobacter‐specific proteins in the bacterial outer membrane. These outer membrane proteins (OMPs) are anchored to the cell surface via a C‐terminal β‐barrel domain, which requires their assembly by the β‐barrel assembly machinery (BAM). Here we have assessed the complexity of the OMP C‐terminal β‐barrel domains employed by H. pylori, and characterized the H. pyloriBAM complex. Around 50 Helicobacter‐specific OMPs were assessed with predictive structural algorithms. The data suggest that H. pylori utilizes a unique β‐barrel architecture that might constitute H. pylori‐specific Type V secretions system. The structural and functional diversity in these proteins is encompassed by their extramembrane domains. Bioinformatic and biochemical characterization suggests that the low β‐barrel‐complexity requires only minimalist assembly machinery. The H. pylori proteins BamA and BamD associate to form a BAM complex, with features of BamA enabling an oligomerization that might represent a mechanism by which a minimalist BAM complex forms a larger, sophisticated machinery capable of servicing the outer membrane proteome of H. pylori.
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Affiliation(s)
- Chaille T. Webb
- Infection & Immunity ProgramBiomedicine Discovery Institute and Department of MicrobiologyMonash UniversityClaytonAustralia
| | - Dilini Chandrapala
- Infection & Immunity ProgramBiomedicine Discovery Institute and Department of MicrobiologyMonash UniversityClaytonAustralia
- Infection & Immunity ProgramBiomedicine Discovery Institute and Department of Biochemistry and Molecular BiologyMonash UniversityClaytonAustralia
| | - Siti Nurbaya Oslan
- Infection & Immunity ProgramBiomedicine Discovery Institute and Department of MicrobiologyMonash UniversityClaytonAustralia
- Department of BiochemistryFaculty of Biotechnology and Biomolecular SciencesUniversiti Putra MalaysiaSerdangSelangorMalaysia
- Enzyme and Microbial Technology Research CenterUniversiti Putra MalaysiaSerdangSelangorMalaysia
| | - Rebecca S. Bamert
- Infection & Immunity ProgramBiomedicine Discovery Institute and Department of MicrobiologyMonash UniversityClaytonAustralia
| | - Rhys D. Grinter
- Infection & Immunity ProgramBiomedicine Discovery Institute and Department of MicrobiologyMonash UniversityClaytonAustralia
| | - Rhys A. Dunstan
- Infection & Immunity ProgramBiomedicine Discovery Institute and Department of MicrobiologyMonash UniversityClaytonAustralia
| | - Rebecca J. Gorrell
- Infection & Immunity ProgramBiomedicine Discovery Institute and Department of MicrobiologyMonash UniversityClaytonAustralia
- Infection & Immunity ProgramBiomedicine Discovery Institute and Department of Biochemistry and Molecular BiologyMonash UniversityClaytonAustralia
| | - Jiangning Song
- Infection & Immunity ProgramBiomedicine Discovery Institute and Department of Biochemistry and Molecular BiologyMonash UniversityClaytonAustralia
- Monash Centre for Data ScienceFaculty of Information TechnologyMonash UniversityMelbourneAustralia
| | - Richard A. Strugnell
- Department of Microbiology & ImmunologyUniversity of MelbourneParkvilleAustralia
| | - Trevor Lithgow
- Infection & Immunity ProgramBiomedicine Discovery Institute and Department of MicrobiologyMonash UniversityClaytonAustralia
| | - Terry Kwok
- Infection & Immunity ProgramBiomedicine Discovery Institute and Department of MicrobiologyMonash UniversityClaytonAustralia
- Infection & Immunity ProgramBiomedicine Discovery Institute and Department of Biochemistry and Molecular BiologyMonash UniversityClaytonAustralia
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56
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Leyn SA, Maezato Y, Romine MF, Rodionov DA. Genomic Reconstruction of Carbohydrate Utilization Capacities in Microbial-Mat Derived Consortia. Front Microbiol 2017; 8:1304. [PMID: 28751880 PMCID: PMC5507952 DOI: 10.3389/fmicb.2017.01304] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 06/28/2017] [Indexed: 11/29/2022] Open
Abstract
Two nearly identical unicyanobacterial consortia (UCC) were previously isolated from benthic microbial mats that occur in a heliothermal saline lake in northern Washington State. Carbohydrates are a primary source of carbon and energy for most heterotrophic bacteria. Since CO2 is the only carbon source provided, the cyanobacterium must provide a source of carbon to the heterotrophs. Available genomic sequences for all members of the UCC provide opportunity to investigate the metabolic routes of carbon transfer between autotroph and heterotrophs. Here, we applied a subsystem-based comparative genomics approach to reconstruct carbohydrate utilization pathways and identify glycohydrolytic enzymes, carbohydrate transporters and pathway-specific transcriptional regulators in 17 heterotrophic members of the UCC. The reconstructed metabolic pathways include 800 genes, near a one-fourth of which encode enzymes, transporters and regulators with newly assigned metabolic functions resulting in discovery of novel functional variants of carbohydrate utilization pathways. The in silico analysis revealed the utilization capabilities for 40 carbohydrates and their derivatives. Two Halomonas species demonstrated the largest number of sugar catabolic pathways. Trehalose, sucrose, maltose, glucose, and beta-glucosides are the most commonly utilized saccharides in this community. Reconstructed regulons for global regulators HexR and CceR include central carbohydrate metabolism genes in the members of Gammaproteobacteria and Alphaproteobacteria, respectively. Genomics analyses were supplemented by experimental characterization of metabolic phenotypes in four isolates derived from the consortia. Measurements of isolate growth on the defined medium supplied with individual carbohydrates confirmed most of the predicted catabolic phenotypes. Not all consortia members use carbohydrates and only a few use complex polysaccharides suggesting a hierarchical carbon flow from cyanobacteria to each heterotroph. In summary, the genomics-based identification of carbohydrate utilization capabilities provides a basis for future experimental studies of carbon flow in UCC.
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Affiliation(s)
- Semen A Leyn
- Sanford-Burnham-Prebys Medical Discovery Institute, La JollaCA, United States.,A. A. Kharkevich Institute for Information Transmission Problems, Russian Academy of SciencesMoscow, Russia
| | - Yukari Maezato
- Biological Sciences Division, Pacific Northwest National Laboratory, RichlandWA, United States
| | - Margaret F Romine
- Biological Sciences Division, Pacific Northwest National Laboratory, RichlandWA, United States
| | - Dmitry A Rodionov
- Sanford-Burnham-Prebys Medical Discovery Institute, La JollaCA, United States.,A. A. Kharkevich Institute for Information Transmission Problems, Russian Academy of SciencesMoscow, Russia
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57
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Tooke FJ, Babot M, Chandra G, Buchanan G, Palmer T. A unifying mechanism for the biogenesis of membrane proteins co-operatively integrated by the Sec and Tat pathways. eLife 2017; 6. [PMID: 28513434 PMCID: PMC5449189 DOI: 10.7554/elife.26577] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 05/15/2017] [Indexed: 11/13/2022] Open
Abstract
The majority of multi-spanning membrane proteins are co-translationally inserted into the bilayer by the Sec pathway. An important subset of membrane proteins have globular, cofactor-containing extracytoplasmic domains requiring the dual action of the co-translational Sec and post-translational Tat pathways for integration. Here, we identify further unexplored families of membrane proteins that are dual Sec-Tat-targeted. We establish that a predicted heme-molybdenum cofactor-containing protein, and a complex polyferredoxin, each require the concerted action of two translocases for their assembly. We determine that the mechanism of handover from Sec to Tat pathway requires the relatively low hydrophobicity of the Tat-dependent transmembrane domain. This, coupled with the presence of C-terminal positive charges, results in abortive insertion of this transmembrane domain by the Sec pathway and its subsequent release at the cytoplasmic side of the membrane. Together, our data points to a simple unifying mechanism governing the assembly of dual targeted membrane proteins.
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Affiliation(s)
- Fiona J Tooke
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Marion Babot
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Govind Chandra
- Department of Molecular Microbiology, John Innes Centre, Norwich, United Kingdom
| | - Grant Buchanan
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Tracy Palmer
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, United Kingdom
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