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Huber ST, Jakobi AJ. Structural biology of microbial gas vesicles: historical milestones and current knowledge. Biochem Soc Trans 2024; 52:205-215. [PMID: 38329160 PMCID: PMC10903477 DOI: 10.1042/bst20230396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 01/10/2024] [Accepted: 01/16/2024] [Indexed: 02/09/2024]
Abstract
Gas vesicles mediate buoyancy-based motility in aquatic bacteria and archaea and are the only protein-based structures known to enclose a gas-filled volume. Their unique physicochemical properties and ingenious architecture rank them among the most intriguing macromolecular assemblies characterised to date. This review covers the 60-year journey in quest for a high-resolution structural model of gas vesicles, first highlighting significant strides made in establishing the detailed ultrastructure of gas vesicles through transmission electron microscopy, X-ray fibre diffraction, atomic force microscopy, and NMR spectroscopy. We then survey the recent progress in cryogenic electron microscopy studies of gas vesicles, which eventually led to a comprehensive atomic model of the mature assembly. Synthesising insight from these structures, we examine possible mechanisms of gas vesicle biogenesis and growth, presenting a testable model to guide future experimental work. We conclude by discussing future directions in the structural biology of gas vesicles, particularly considering advancements in AI-driven structure prediction.
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Affiliation(s)
- Stefan T. Huber
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Arjen J. Jakobi
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands
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Huber ST, Terwiel D, Evers WH, Maresca D, Jakobi AJ. Cryo-EM structure of gas vesicles for buoyancy-controlled motility. Cell 2023; 186:975-986.e13. [PMID: 36868215 PMCID: PMC9994262 DOI: 10.1016/j.cell.2023.01.041] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 11/14/2022] [Accepted: 01/30/2023] [Indexed: 03/05/2023]
Abstract
Gas vesicles are gas-filled nanocompartments that allow a diverse group of bacteria and archaea to control their buoyancy. The molecular basis of their properties and assembly remains unclear. Here, we report the 3.2 Å cryo-EM structure of the gas vesicle shell made from the structural protein GvpA that self-assembles into hollow helical cylinders closed off by cone-shaped tips. Two helical half shells connect through a characteristic arrangement of GvpA monomers, suggesting a mechanism of gas vesicle biogenesis. The fold of GvpA features a corrugated wall structure typical for force-bearing thin-walled cylinders. Small pores enable gas molecules to diffuse across the shell, while the exceptionally hydrophobic interior surface effectively repels water. Comparative structural analysis confirms the evolutionary conservation of gas vesicle assemblies and demonstrates molecular features of shell reinforcement by GvpC. Our findings will further research into gas vesicle biology and facilitate molecular engineering of gas vesicles for ultrasound imaging.
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Affiliation(s)
- Stefan T Huber
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft 2628CD, the Netherlands
| | - Dion Terwiel
- Department of Imaging Physics, Delft University of Technology, Delft 2628CD, the Netherlands
| | - Wiel H Evers
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft 2628CD, the Netherlands
| | - David Maresca
- Department of Imaging Physics, Delft University of Technology, Delft 2628CD, the Netherlands.
| | - Arjen J Jakobi
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft 2628CD, the Netherlands.
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Cai K, Xu BY, Jiang YL, Wang Y, Chen Y, Zhou CZ, Li Q. The model cyanobacteria Anabaena sp. PCC 7120 possess an intact but partially degenerated gene cluster encoding gas vesicles. BMC Microbiol 2020; 20:110. [PMID: 32375647 PMCID: PMC7204071 DOI: 10.1186/s12866-020-01805-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 04/27/2020] [Indexed: 11/23/2022] Open
Abstract
Background Bacterial gas vesicles, composed of two major gas vesicle proteins and filled with gas, are a unique class of intracellular bubble-like nanostructures. They provide buoyancy for cells, and thus play an essential role in the growth and survival of aquatic and soil microbes. Moreover, the gas vesicle could be applied to multimodal and noninvasive biological imaging as a potential nanoscale contrast agent. To date, cylinder-shaped gas vesicles have been found in several strains of cyanobacteria. However, whether the functional gas vesicles could be produced in the model filamentous cyanobacteria Anabaena sp. PCC 7120 remains controversial. Results In this study, we found that an intact gvp gene cluster indeed exists in the model filamentous cyanobacteria Anabaena sp. PCC 7120. Real-time PCR assays showed that the gvpA gene is constitutively transcribed in vivo, and its expression level is upregulated at low light intensity and/or high growth temperature. Functional expression of this intact gvp gene cluster enables the recombinant Escherichia coli to gain the capability of floatation in the liquid medium, thanks to the assembly of irregular gas vesicles. Furthermore, crystal structure of GvpF in combination with enzymatic activity assays of GvpN suggested that these two auxiliary proteins of gas vesicle are structurally and enzymatically conserved, respectively. Conclusions Our findings show that the laboratory strain of model filamentous cyanobacteria Anabaena sp. PCC 7120 possesses an intact but partially degenerated gas vesicle gene cluster, indicating that the natural isolate might be able to produce gas vesicles under some given environmental stimuli for better floatation.
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Affiliation(s)
- Kun Cai
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, 230027, Anhui, China
| | - Bo-Ying Xu
- College of Life Sciences, Chongqing Normal University, Chongqing, 401331, China
| | - Yong-Liang Jiang
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, 230027, Anhui, China
| | - Ying Wang
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, 230027, Anhui, China
| | - Yuxing Chen
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, 230027, Anhui, China
| | - Cong-Zhao Zhou
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, 230027, Anhui, China
| | - Qiong Li
- Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, 230027, Anhui, China.
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Inorganic carbon and nitrogen assimilation in cellular compartments of a benthic kleptoplastic foraminifer. Sci Rep 2018; 8:10140. [PMID: 29973634 PMCID: PMC6031614 DOI: 10.1038/s41598-018-28455-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 06/20/2018] [Indexed: 11/08/2022] Open
Abstract
Haynesina germanica, an ubiquitous benthic foraminifer in intertidal mudflats, has the remarkable ability to isolate, sequester, and use chloroplasts from microalgae. The photosynthetic functionality of these kleptoplasts has been demonstrated by measuring photosystem II quantum efficiency and O2 production rates, but the precise role of the kleptoplasts in foraminiferal metabolism is poorly understood. Thus, the mechanism and dynamics of C and N assimilation and translocation from the kleptoplasts to the foraminiferal host requires study. The objective of this study was to investigate, using correlated TEM and NanoSIMS imaging, the assimilation of inorganic C and N (here ammonium, NH4+) in individuals of a kleptoplastic benthic foraminiferal species. H. germanica specimens were incubated for 20 h in artificial seawater enriched with H13CO3- and 15NH4+ during a light/dark cycle. All specimens (n = 12) incorporated 13C into their endoplasm stored primarily in the form of lipid droplets. A control incubation in darkness resulted in no 13C-uptake, strongly suggesting that photosynthesis is the process dominating inorganic C assimilation. Ammonium assimilation was observed both with and without light, with diffuse 15N-enrichment throughout the cytoplasm and distinct 15N-hotspots in fibrillar vesicles, electron-opaque bodies, tubulin paracrystals, bacterial associates, and, rarely and at moderate levels, in kleptoplasts. The latter observation might indicate that the kleptoplasts are involved in N assimilation. However, the higher N assimilation observed in the foraminiferal endoplasm incubated without light suggests that another cytoplasmic pathway is dominant, at least in darkness. This study clearly shows the advantage provided by the kleptoplasts as an additional source of carbon and provides observations of ammonium uptake by the foraminiferal cell.
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Miller TR, Beversdorf LJ, Weirich CA, Bartlett SL. Cyanobacterial Toxins of the Laurentian Great Lakes, Their Toxicological Effects, and Numerical Limits in Drinking Water. Mar Drugs 2017; 15:E160. [PMID: 28574457 PMCID: PMC5484110 DOI: 10.3390/md15060160] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 04/22/2017] [Accepted: 05/02/2017] [Indexed: 02/07/2023] Open
Abstract
Cyanobacteria are ubiquitous phototrophic bacteria that inhabit diverse environments across the planet. Seasonally, they dominate many eutrophic lakes impacted by excess nitrogen (N) and phosphorus (P) forming dense accumulations of biomass known as cyanobacterial harmful algal blooms or cyanoHABs. Their dominance in eutrophic lakes is attributed to a variety of unique adaptations including N and P concentrating mechanisms, N₂ fixation, colony formation that inhibits predation, vertical movement via gas vesicles, and the production of toxic or otherwise bioactive molecules. While some of these molecules have been explored for their medicinal benefits, others are potent toxins harmful to humans, animals, and other wildlife known as cyanotoxins. In humans these cyanotoxins affect various tissues, including the liver, central and peripheral nervous system, kidneys, and reproductive organs among others. They induce acute effects at low doses in the parts-per-billion range and some are tumor promoters linked to chronic diseases such as liver and colorectal cancer. The occurrence of cyanoHABs and cyanotoxins in lakes presents challenges for maintaining safe recreational aquatic environments and the production of potable drinking water. CyanoHABs are a growing problem in the North American (Laurentian) Great Lakes basin. This review summarizes information on the occurrence of cyanoHABs in the Great Lakes, toxicological effects of cyanotoxins, and appropriate numerical limits on cyanotoxins in finished drinking water.
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Affiliation(s)
- Todd R Miller
- Joseph J. Zilber School of Public Health, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA.
| | - Lucas J Beversdorf
- Joseph J. Zilber School of Public Health, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA.
| | - Chelsea A Weirich
- Joseph J. Zilber School of Public Health, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA.
| | - Sarah L Bartlett
- Joseph J. Zilber School of Public Health, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA.
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6
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Lecina M, Sanchez B, Solà C, Prat J, Roldán M, Hernández M, Bragós R, Paredes CJ, Cairó JJ. Structural changes of Arthrospira sp. after low energy sonication treatment for microalgae harvesting: Elucidating key parameters to detect the rupture of gas vesicles. BIORESOURCE TECHNOLOGY 2017; 223:98-104. [PMID: 27788433 DOI: 10.1016/j.biortech.2016.10.030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 10/07/2016] [Accepted: 10/08/2016] [Indexed: 06/06/2023]
Abstract
The buoyancy suppression by low energy sonication (LES) treatment (0.8W·mL-1, 20kHz, 10s) has recently been proposed as an initial harvesting step for Arthrospira sp. This paper aims to describe the structural changes in Arthrospira sp. after LES treatment and to present how these structural changes affect the results obtained by different analytical techniques. Transmission electron microscopy (TEM) micrographs of trichomes evidenced the gas vesicles rupture but also revealed a rearrangement of thylakoids and more visible phycobilisomes were observed. Differences between treated and untreated samples were detected by confocal microscopy, flow cytometry and optical microscopy but not by electrical impedance spectroscopy (EIS). After LES treatment, 2-fold increase in autofluorescence at 610/660nm was measured (phycocyanin/allophycocyanin emission wavelengths) and a ten-fold decrease in side scatter light intensity (due to a reduction of trichome's inner complexity). This was further confirmed by optical microscopy showing changes on trichomes appearance (from wrinkled to smooth).
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Affiliation(s)
- Martí Lecina
- Department of Chemial, Biological and Environmental Engineering, Escola d'Enginyeria, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
| | - Benjamin Sanchez
- Electronic and Biomedical Instrumentation Group, Department of Electronic Engineering, Universitat Politècnica de Catalunya (UPC), Campus Nord, C-4, C/ Jordi Girona 1-3, 08034 Barcelona, Spain
| | - Carles Solà
- Department of Chemial, Biological and Environmental Engineering, Escola d'Enginyeria, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | - Jordi Prat
- Department of Chemial, Biological and Environmental Engineering, Escola d'Enginyeria, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | - Mònica Roldán
- Servei de Microscòpia, Universitat Autònoma de Barcelona, Edifici C, Facultat de Ciències, 08193 Bellaterra, Spain
| | - Mariona Hernández
- Dep. Productes Naturals, Biologia Vegetal i Edafologia, Facultat de Farmàcia, Universitat de Barcelona, Av. Joan XXIII s/n, 08028 Barcelona, Spain
| | - Ramon Bragós
- Electronic and Biomedical Instrumentation Group, Department of Electronic Engineering, Universitat Politècnica de Catalunya (UPC), Campus Nord, C-4, C/ Jordi Girona 1-3, 08034 Barcelona, Spain
| | - Carlos J Paredes
- Department of Chemial, Biological and Environmental Engineering, Escola d'Enginyeria, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | - Jordi J Cairó
- Department of Chemial, Biological and Environmental Engineering, Escola d'Enginyeria, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
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7
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Tashiro Y, Monson RE, Ramsay JP, Salmond GPC. Molecular genetic and physical analysis of gas vesicles in buoyant enterobacteria. Environ Microbiol 2016; 18:1264-76. [PMID: 26743231 PMCID: PMC4982088 DOI: 10.1111/1462-2920.13203] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 12/29/2015] [Indexed: 11/29/2022]
Abstract
Different modes of bacterial taxis play important roles in environmental adaptation, survival, colonization and dissemination of disease. One mode of taxis is flotation due to the production of gas vesicles. Gas vesicles are proteinaceous intracellular organelles, permeable only to gas, that enable flotation in aquatic niches. Gene clusters for gas vesicle biosynthesis are partially conserved in various archaea, cyanobacteria, and some proteobacteria, such as the enterobacterium, Serratia sp. ATCC 39006 (S39006). Here we present the first systematic analysis of the genes required to produce gas vesicles in S39006, identifying how this differs from the archaeon Halobacterium salinarum. We define 11 proteins essential for gas vesicle production. Mutation of gvpN or gvpV produced small bicone gas vesicles, suggesting that the cognate proteins are involved in the morphogenetic assembly pathway from bicones to mature cylindrical forms. Using volumetric compression, gas vesicles were shown to comprise 17% of S39006 cells, whereas in Escherichia coli heterologously expressing the gas vesicle cluster in a deregulated environment, gas vesicles can occupy around half of cellular volume. Gas vesicle production in S39006 and E. coli was exploited to calculate the instantaneous turgor pressure within cultured bacterial cells; the first time this has been performed in either strain.
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Affiliation(s)
- Yosuke Tashiro
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK.,Applied Chemistry and Biochemical Engineering Course, Department of Engineering, Graduate School of Integrated Science and Technology, Shizuoka University, Hamamatsu, 432-8561, Japan
| | - Rita E Monson
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK
| | - Joshua P Ramsay
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK.,Curtin Health Innovation Research Institute Biosciences Precinct, Faculty of Health Sciences, Curtin University, Bentley, WA, 6102, Australia
| | - George P C Salmond
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK
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8
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Durham WM, Stocker R. Thin phytoplankton layers: characteristics, mechanisms, and consequences. ANNUAL REVIEW OF MARINE SCIENCE 2012; 4:177-207. [PMID: 22457973 DOI: 10.1146/annurev-marine-120710-100957] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
For over four decades, aggregations of phytoplankton known as thin layers have been observed to harbor large amounts of photosynthetic cells within narrow horizontal bands. Field observations have revealed complex linkages among thin phytoplankton layers, the physical environment, cell behavior, and higher trophic levels. Several mechanisms have been proposed to explain layer formation and persistence, in the face of the homogenizing effect of turbulent dispersion. The challenge ahead is to connect mechanistic hypotheses with field observations to gain better insight on the phenomena that shape layer dynamics. Only through a mechanistic understanding of the relevant biological and physical processes can we begin to predict the effect of thin layers on the ecology of phytoplankton and higher organisms.
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Affiliation(s)
- William M Durham
- Ralph M. Parsons Laboratory, Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
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9
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Sublimi Saponetti M, Bobba F, Salerno G, Scarfato A, Corcelli A, Cucolo A. Morphological and structural aspects of the extremely halophilic archaeon Haloquadratum walsbyi. PLoS One 2011; 6:e18653. [PMID: 21559517 PMCID: PMC3084702 DOI: 10.1371/journal.pone.0018653] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Accepted: 03/13/2011] [Indexed: 11/28/2022] Open
Abstract
Ultrathin square cell Haloquadratum walsbyi from the Archaea domain are the most abundant microorganisms in the hypersaline water of coastal salterns and continental salt lakes. In this work, we explore the cell surface of these microorganisms using amplitude-modulation atomic-force microscopy in nearly physiological conditions. We demonstrate the presence of a regular corrugation with a periodicity of 16–20 nm attributed to the surface layer (S-layer) protein lattice, striped domains asymmetrically distributed on the cell faces and peculiar bulges correlated with the presence of intracellular granules. Besides, subsequent images of cell evolution during the drying process indicate the presence of an external capsule that might correspond to the giant protein halomucin, predicted by the genome but never before observed by other microscopy studies.
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Affiliation(s)
- Matilde Sublimi Saponetti
- Department of Physics and Research Centre NanoMateS, University of Salerno and SPIN-CNR, Fisciano, Italy.
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10
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Paerl HW. Partitioning of CO(2) Fixation in the Colonial Cyanobacterium Microcystis aeruginosa: Mechanism Promoting Formation of Surface Scums. Appl Environ Microbiol 2010; 46:252-9. [PMID: 16346344 PMCID: PMC239296 DOI: 10.1128/aem.46.1.252-259.1983] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Constraints on inorganic carbon (C(i)) availability stimulated buoyancy in natural, photosynthetically active populations of the colonial blue-green alga (cyanobacterium) Microcystis aeruginosa. In nonmixed eutrophic river water and cultures, O(2) evolution determinations indicated C(i) limitation of photosynthesis, which was overcome either by CO(2) additions to the aqueous phase or by exposure of buoyant colonies to atmospheric CO(2). Microautoradiographs of M. aeruginosa colonies revealed partitioning of CO(2) fixation and photosynthate accumulation between peripheral and internal cells, particularly in large colonies. When illuminated colonies were suspended in the aqueous phase, peripheral cells accounted for at least 90% of the CO(2) assimilation, whereas internal cells remained unlabeled. However, when CO(2) was allowed to diffuse into colonies 15 min before illumination, a more uniform distribution of labeling was observed. Resultant differences in labeling patterns were most likely due to peripheral cells more exclusively utilizing CO(2) when ambient C(i) concentrations were low. Among colonies located at the air-water interface, internal cells showed an increased share of photosynthate production when atmospheric CO(2) was supplied. This indicated that C(i) transport was restricted in large colonies below the water surface, forcing internal cells to maintain a high degree of buoyancy, thus promoting the formation of surface scums. At the surface, C(i) restrictions were alleviated. Accordingly, scum formation appears to have an ecological function, allowing cyanobacteria access to atmospheric CO(2) when the C(i) concentration is growth limiting in the water column.
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Affiliation(s)
- H W Paerl
- Institute of Marine Sciences, University of North Carolina, Morehead City, North Carolina 28557
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11
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Sivertsen AC, Bayro MJ, Belenky M, Griffin RG, Herzfeld J. Solid-state NMR evidence for inequivalent GvpA subunits in gas vesicles. J Mol Biol 2009; 387:1032-9. [PMID: 19232353 DOI: 10.1016/j.jmb.2009.02.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Revised: 02/04/2009] [Accepted: 02/10/2009] [Indexed: 11/18/2022]
Abstract
Gas vesicles are organelles that provide buoyancy to the aquatic microorganisms that harbor them. The gas vesicle shell consists almost exclusively of the hydrophobic 70-residue gas vesicle protein A, arranged in an ordered array. Solid-state NMR spectra of intact collapsed gas vesicles from the cyanobacterium Anabaena flos-aquae show duplication of certain gas vesicle protein A resonances, indicating that specific sites experience at least two different local environments. Interpretation of these results in terms of an asymmetric dimer repeat unit can reconcile otherwise conflicting features of the primary, secondary, tertiary, and quaternary structures of the gas vesicle protein. In particular, the asymmetric dimer can explain how the hydrogen bonds in the beta-sheet portion of the molecule can be oriented optimally for strength while promoting stabilizing aromatic and electrostatic side-chain interactions among highly conserved residues and creating a large hydrophobic surface suitable for preventing water condensation inside the vesicle.
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Affiliation(s)
- Astrid C Sivertsen
- Department of Chemistry, Brandeis University, Waltham, MA 02454-9110, USA
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Li Z, Ohno T, Sato H, Sakugawa T, Akiyama H, Kunitomo S, Sasaki K, Ayukawa M, Fujiwara H. A method of water-bloom prevention using underwater pulsed streamer discharge. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2008; 43:1209-1214. [PMID: 18584437 DOI: 10.1080/10934520802171782] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Water-bloom (also named as cyanobacterial bloom) is becoming a very serious pollution problem all over the world. In this paper, a new method for the prevention of water blooms using underwater streamer discharges is reported. Blumlein pulse forming network (B-PFN) and magnetic pulse compression circuit (MPC) were employed to apply high voltage pulses to water with cyanobacterial cells. The experimental results confirmed that the cyanobacterial cells sank to the bottom of the water bodies after applying underwater streamer discharges. Transmission electron microscope (TEM) observations showed that the discharge collapsed the gas vesicles (GVs)-the intercellular structure of water-bloom forming cyanobaterial cells-and did not affect the other part of contents of the cells. Cynabacterial cells lost buoyancy and sank to the bottom of the water bodies. Because of lower temperature and without enough sunlight at the bottom of the water bodies, the cells can be prevented from proliferation too quickly.
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Affiliation(s)
- Zi Li
- School of Engineering, Toyo University, Kawagoe, Saitama, Japan.
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13
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Meffert ME, Oberhäuser R, Overbeck J. Morphology and taxonomy ofOscillatoria redekei(Cyanophyta). ACTA ACUST UNITED AC 2007. [DOI: 10.1080/00071618100650091] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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14
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Booker M, Walsby A. Bloom formation and stratification by a planktonic blue-green alga in an experimental water column. ACTA ACUST UNITED AC 2007. [DOI: 10.1080/00071618100650471] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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15
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Konopka A. Buoyancy regulation and vertical migration byOscillatoria rubescensin Crooked Lake, Indiana. ACTA ACUST UNITED AC 2007. [DOI: 10.1080/00071618200650451] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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16
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Shear H, Walsby A. An investigation into the possible light-shielding role of gas vacuoles in a planktonic blue-green alga. ACTA ACUST UNITED AC 2007. [DOI: 10.1080/00071617500650231] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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17
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Belenky M, Meyers R, Herzfeld J. Subunit structure of gas vesicles: a MALDI-TOF mass spectrometry study. Biophys J 2004; 86:499-505. [PMID: 14695294 PMCID: PMC1303817 DOI: 10.1016/s0006-3495(04)74128-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Many aquatic microorganisms use gas vesicles to regulate their depth in the water column. The molecular basis for the novel physical properties of these floatation organelles remains mysterious due to the inapplicability of either solution or single crystal structural methods. In the present study, some folding constraints for the approximately 7-kDa GvpA building blocks of the vesicles are established via matrix-assisted laser desorption ionization time-of-flight mass spectrometry studies of intact and proteolyzed vesicles from the cyanobacterium Anabaena flos-aquae and the archaea Halobacterium salinarum. The spectra of undigested vesicles show no evidence of posttranslational modification of the GvpA. The extent of carboxypeptidase digestion shows that the alanine rich C-terminal pentapeptide of GvpA is exposed to the surface in both organisms. The bonds that are cleaved by Trypsin and GluC are exclusively in the extended N-terminus of the Anabaena flos-aquae protein and in the extended C-terminus of the Halobacterium salinarum protein. All the potentially cleavable peptide bonds in the central, highly conserved portion of the protein appear to be shielded from protease attack in spite of the fact that some of the corresponding side chains are almost certainly exposed to the aqueous medium.
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Affiliation(s)
- Marina Belenky
- Department of Chemistry and Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02454, USA
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18
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Offner S, Ziese U, Wanner G, Typke D, Pfeifer F. Structural characteristics of halobacterial gas vesicles. MICROBIOLOGY (READING, ENGLAND) 1998; 144 ( Pt 5):1331-1342. [PMID: 9611808 DOI: 10.1099/00221287-144-5-1331] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Gas vesicle formation in halophilic archaea is encoded by a DNA region (the vac region) containing 14 different genes: gvpACNO and gvpDEFGHIJKLM. In Halobacterium salinarum PHH1 (which expresses the p-vac region from plasmid pHH1), gas vesicles are spindle shaped, whereas predominantly cylindrical gas vesicles are synthesized by the chromosomal c-vac region of H. salinarum PHH4 and the single chromosomal mc-vac region of Haloferax mediterranei. Homologous complementation of gvp gene clusters derived from the chromosomal c-vac region led to cylindrical gas vesicles in transformants and proved that the activity of the c-gvpA promoter depended on a gene product from the c-gvpE-M DNA region. Heterologous complementation experiments with transcription units of different vac regions demonstrated that the formation of chimeric gas vesicles was possible. Comparison of micrographs of wild-type and chimeric gas vesicles indicated that the shape was not exclusively determined by GvpA, the major structural protein of the gas vesicle wall. More likely, a dynamic equilibrium of several gvp gene products was responsible for determination of the shape. Transmission electron microscopy of frozen hydrated, wild-type gas vesicles showed moiré patterns due to the superposition of the front and back parts of the ribbed gas vesicle envelope. Comparison of projections of model helices with the moiré pattern seen on the cylindrical part of the gas vesicles provided evidence that the ribs formed a helix of low pitch and not a stack of hoops.
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Affiliation(s)
- Sonja Offner
- Institut für Mikrobiologie und Genetik, Technische Universität Darmstadt, Schnittspahnstr. 10, D-64287 Darmstadt, Germany
| | - Ulrike Ziese
- Max-Planck-Institut für Biochemie, D-82152 Martinsried, Germany
| | - Gerhard Wanner
- Institut für Botanik, Ludwig-Maximilians-Universität München, D-80992 München, Germany
| | - Dieter Typke
- Max-Planck-Institut für Biochemie, D-82152 Martinsried, Germany
| | - Felicitas Pfeifer
- Institut für Mikrobiologie und Genetik, Technische Universität Darmstadt, Schnittspahnstr. 10, D-64287 Darmstadt, Germany
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19
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Abstract
Theelastic compressibility of gas vesicles isolated from
Anabaena flos-aquae
has been measured with a specially constructed apparatus. The gas vesicle suspension was contained in a glass tube, closed at one end with a piston allowing volume adjustment and attached at the other end to a microcapillary, and was subjected to pressure from compressed air. The elastic compressibility of the gas vesicle suspension was determined by applying or removing pressure and measuring the ensuing displacement of the meniscus in the capillary with a vernier microscope. After allowing for the compressibility of the compression tube and of water in the suspension, the compressibility of the intact gas vesicles has been calculated to be 0.00155 bar
-1
, and the elastic bulk modulus 645 bar. The elastic modulus of the protein that forms the gas vesicle wall can also be calculated from these measurements; it is 27500 bar. These measurements confirm that the gas vesicle is a rigid structure and show that the buoyancy provided by them will be relatively unaffected by pressures that do not actually cause gas vesicle collapse. The apparatus described can also be used to provide a direct measurement of the volume of gas vesicle gas space present in a suspension of a gas-vacuolate organism, and to investigate the gas vesicle critical collapse pressure. Gas vesicles appear to collapse by instability failure but the pressure at which this occurs, about 6 bar, is higher than would be predicted from knowledge of the dimensions and elastic modulus of the gas vesicle wall. This supports the idea that the orientation of the ribs, which form the structure, provides ring-stiffening support.
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20
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Abstract
Picoplankton consists of those organisms found in the open waters of seas and lakes which are capable of passing through a filter with 2 μm pores but not through one with 0.2 μm pores. Cells in this size range are well adapted to planktonic life in that they sink extremely slowly and are more efficient than larger forms in taking up nutrients and absorbing radiant energy. Picophytoplankton includes coccoid cyanobacteria and a variety of eukaryotic algal forms. Strains studied in the laboratory have all been found to show maximum growth at relatively low irradiances, the eukaryotic forms being more efficient than the cyanobacteria in utilizing the blue light which predominates at the bottom of the photic zone in clear oceanic waters. Oceanic strains of coccoid cyanobacteria, however, are characterized by high concentrations of phycoerythrin, which appears to function as a nitrogenous reserve as well as an accessory pigment in photosynthesis. The seasonal and spatial distribution of picophytoplankton seems explicable in terms of these physiological characteristics. Numbers of coccoid cyanobacteria have shown a striking correlation with temperature in a number of different situations. Heterotrophic bacteria are also included in the picoplankton, and a review of the information concerning them suggests that they form a highly dynamic population subsisting on dissolved organic matter liberated by living phytoplankton and zooplankton and by decomposition of dead matter. The productivity of this population in the euphotic zone approaches that of the phytoplankton. Both the picophytoplankton and the bacterioplankton are preyed on by phagotrophic flagellates. Both bacteria and flagellates are active in regeneration of mineral nutrients. Regardless of the salinity, temperature or nutrient status of the water, the numbers of heterotrophic bacteria, picophytoplankton and flagellates tend to be around 10
6
, 10
4
and 10
3
organisms per millilitre respectively. It is suggested that these populations form a basic, self-sustaining and self-regulating community in all natural waters. From present information, it seems that little of the energy which passes through this community finds its way into the larger planktonic organisms, but the role of picoplankton in recycling nutrient elements is of great importance in the marine ecosystem.
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21
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Abstract
Heterocysts of the cyanobacterium
Anabaena flos-aquae
retina gas vacuoles for several days after differentiation. It is demonstrated that the rate of gas diffusion into a heterocyst that is near an overlying gas phase can be determined approximately from observations on the rate of gas pressure rise required to collapse 50% of its gas vacuoles. The mean permeability coefficient (
α
) of heterocysts O
2
and N
2
was found to be 0.3
s
-1
. From this it was calculated that the average permeability (
k
) of the heterocyst surface layer is about 0.4 μm
s
-1
(within a factor of 2). This is probably within the range that could be provided by a few layers of the 26-C glycolipids in the heterocyst envelope. It is likely, but not proven, that the main route for gas diffusion is through the envelope rather than through the terminal pores of the heterocyst. From measurements of cell nitrogen content (2.7 pg). doubling time (3 days) and heterocyst: vegetative cell ratio (1:24) it was calculated that the average heterocyst fixed 5.9 x 10
-18
mol N
2
s
-1
; this must equal the diffusion rate of N
2
inside the average heterocyst that was 22% below the outside air-saturated concentration. the maximum N
2
fixation rate allowed by the estimated permeability coefficeint would be 2.7 x 10
-17
mol
s
-1
per heterocyst, slightly greater than the maximum calcualted N
2
fixation rate. The observed permeability coefficient is low enough for the oxygen concentration in the heterocyst to be maintained close to zero by the probable rate of respiration, providing an anaerobic environment for nitrogenase. The rate of O
2
diffusion will limit the N
2
-fixation rate in the dark by limiting the rate at which ATP is supplied by oxidative phosphorylation.
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22
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McMaster TJ, Miles MJ, Walsby AE. Direct observation of protein secondary structure in gas vesicles by atomic force microscopy. Biophys J 1996; 70:2432-36. [PMID: 9172769 PMCID: PMC1225220 DOI: 10.1016/s0006-3495(96)79813-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The protein that forms the gas vesicle in the cyanobacterium Anabaena flos-aquae has been imaged by atomic force microscopy (AFM) under liquid at room temperature. The protein constitutes "ribs" which, stacked together, form the hollow cylindrical tube and conical end caps of the gas vesicle. By operating the microscope in deflection mode, it has been possible to achieve sub-nanometer resolution of the rib structure. The lateral spacing of the ribs was found to be 4.6 +/- 0.1 nm. At higher resolution the ribs are observed to consist of pairs of lines at an angle of approximately 55 degrees to the rib axis, with a repeat distance between each line of 0.57 +/- 0.05 nm along the rib axis. These observed dimensions and periodicities are consistent with those determined from previous x-ray diffraction studies, indicating that the protein is arranged in beta-chains crossing the rib at an angle of 55 degrees to the rib axis. The AFM results confirm the x-ray data and represent the first direct images of a beta-sheet protein secondary structure using this technique. The orientation of the GvpA protein component of the structure and the extent of this protein across the ribs have been established for the first time.
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Affiliation(s)
- T J McMaster
- H.H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL, England.
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23
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Abstract
Cyanobacteria have had a profound and unparalleled biogeochemical impact on the earth's biosphere. As the first oxygenic phototrophs, cyanobacteria were responsible for the transition from anaerobic to aerobic life. Ironically, molecular oxygen (O2) is inhibitory to critical components of cyanobacterial metabolism, including photosynthesis and nitrogen fixation. Cyanobacteria have developed a great variety of biochemical, structural, and biotic adaptations ensuring optimal growth and proliferation in diverse oxic environments to counter this difficult situation. Structurally, cyanobacteria reveal remarkable diversity, including the formation of highly differentiated, O2-deplete cells (heterocysts), multicellularity as trichomes, and aggregates, that, among N2-fixing genera, facilitate division of labor between aerobic and anaerobic processes. Cyanobacteria enjoy unique consortial and symbiotic associations with other microorganisms, higher plants, and animals, in which O2 consumption is closely coupled in time and space to its production. Because as prokaryotes they are devoid of O2-consuming organelles (e.g., mitochondria), cyanobacteria have developed alternative strategies for locally protecting O2-sensitive processes, including consortial relationships with other microorganisms. Specific organic compounds released by cyanobacteria are capable of chemotactically attracting bacterial consorts, which in turn attach to the host cyanobacteria, consume O2, and recycle inorganic nutrients within the cyanobacterial "phycosphere." Multicellularity and aggregation lead to localized O2 gradients and hypoxic/anoxic microzones in which O2-sensitive processes can coexist. Microscale partitioning of O2-producing and O2-inhibited processes promotes contiguous and effective metabolite and nutrient exchange between these processes in oxygenated waters, representing a bulk of the world's oceanic and freshwater ecosystems.
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Affiliation(s)
- H W Paerl
- Institute of Marine Sciences, University of North Carolina at Chapel Hill, Morehead City 28557, USA
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24
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Abstract
The gas vesicle is a hollow structure made of protein. It usually has the form of a cylindrical tube closed by conical end caps. Gas vesicles occur in five phyla of the Bacteria and two groups of the Archaea, but they are mostly restricted to planktonic microorganisms, in which they provide buoyancy. By regulating their relative gas vesicle content aquatic microbes are able to perform vertical migrations. In slowly growing organisms such movements are made more efficiently than by swimming with flagella. The gas vesicle is impermeable to liquid water, but it is highly permeable to gases and is normally filled with air. It is a rigid structure of low compressibility, but it collapses flat under a certain critical pressure and buoyancy is then lost. Gas vesicles in different organisms vary in width, from 45 to > 200 nm; in accordance with engineering principles the narrower ones are stronger (have higher critical pressures) than wide ones, but they contain less gas space per wall volume and are therefore less efficient at providing buoyancy. A survey of gas-vacuolate cyanobacteria reveals that there has been natural selection for gas vesicles of the maximum width permitted by the pressure encountered in the natural environment, which is mainly determined by cell turgor pressure and water depth. Gas vesicle width is genetically determined, perhaps through the amino acid sequence of one of the constituent proteins. Up to 14 genes have been implicated in gas vesicle production, but so far the products of only two have been shown to be present in the gas vesicle: GvpA makes the ribs that form the structure, and GvpC binds to the outside of the ribs and stiffens the structure against collapse. The evolution of the gas vesicle is discussed in relation to the homologies of these proteins.
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Affiliation(s)
- A E Walsby
- Department of Botany, University of Bristol, England
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25
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Pfeifer F, Englert C. Function and biosynthesis of gas vesicles in halophilic Archaea. J Bioenerg Biomembr 1992; 24:577-85. [PMID: 1459989 DOI: 10.1007/bf00762350] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The proteinaceous gas vesicles produced by various microorganisms including halophilic Archaea are hollow, gas-filled structures with a hydrophobic inner and a hydrophilic outer surface. The structural components of gas vesicles and their biosynthesis are still under investigation; an 8-kDa polypeptide appears to be the major constituent of the gas-vesicle envelope. Genetic analysis of the halobacterial gas-vesicle synthesis revealed an unexpected complexity: about 14 genes organized in three transcription units are involved in gas-vesicle structure, assembly, and gene regulation. Here we describe the comparison of three different genomic regions encoding gas vesicles in Halobacterium salinarium (p-vac and c-vac regions) and Haloferax mediterranei (mc-vac region) and speculate on the function of the gene products involved in gas-vesicle synthesis.
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Affiliation(s)
- F Pfeifer
- Max-Planck-Institut für Biochemie, Martinsried, Germany
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26
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Affiliation(s)
- A E Walsby
- Department of Botany, University of Bristol, U.K
| | | |
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27
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Staley JT, Irgens RL, Herwig RP. Gas Vacuolate Bacteria from the Sea Ice of Antarctica. Appl Environ Microbiol 1989; 55:1033-6. [PMID: 16347887 PMCID: PMC184243 DOI: 10.1128/aem.55.4.1033-1036.1989] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Gas-vacuolate heterotrophic bacteria from marine habitats are reported here for the first time. They have been isolated from Antarctic sea ice microbial communities and the underlying water column. The predominant gas-vacuolate bacterium from the sea ice is filamentous and pigmented, whereas those of the water column are unicellular and nonpigmented. The highest concentrations of bacteria in sea ice were found in conjunction with the highest algal (chlorophyll
a
) concentrations.
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Affiliation(s)
- J T Staley
- Department of Microbiology SC-42, University of Washington, Seattle, Washington 98195, and Department of Biology, Southwest Missouri State University, Springfield, Missouri 65802
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28
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Damerval T, Castets AM, Guglielmi G, Houmard J, Tandeau de Marsac N. Occurrence and distribution of gas vesicle genes among cyanobacteria. J Bacteriol 1989; 171:1445-52. [PMID: 2493445 PMCID: PMC209765 DOI: 10.1128/jb.171.3.1445-1452.1989] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Gas vesicles (GV) are specialized cell inclusions providing many aquatic procaryotes with buoyancy. In the cyanobacterium Calothrix sp. strain PCC 7601, at least four genes are involved in GV formation. One of those, gvpA1, encodes the major structural GV protein (70 amino acids) and belongs to a multigene family (gvpA1, gvpA2, gvpD). The fourth gene, gvpC, encodes a 162-amino-acid protein, the function of which is still unclear. We used the Calothrix gvpA1 and gvpC genes as probes to perform Southern hybridization experiments with DNA extracted from various cyanobacterial strains. The gvpA gene was found in all the strains that synthesize GV, indicating that its product is an obligatory component of GV. Furthermore, it was found to occur as multiple copies in most of the strains tested. The gvpC gene was only detected in some strains able to synthesize a large amount of GV within a short period. This suggests that the gvpC gene product is a dispensable protein for GV formation and is involved in the efficiency of the assembly process. Based on the occurrence of the gvp genes and on DNA-DNA hybridization patterns, genus assignments are discussed.
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Affiliation(s)
- T Damerval
- CNRS URA150, Département de Biochimie et Génétique Moléculaire, Institut Pasteur, Paris, France
| | | | | | | | | |
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29
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Surek B, Pillay B, Rdest U, Beyreuther K, Goebel W. Evidence for two different gas vesicle proteins and genes in Halobacterium halobium. J Bacteriol 1988; 170:1746-51. [PMID: 3350789 PMCID: PMC211026 DOI: 10.1128/jb.170.4.1746-1751.1988] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Most halobacteria produce gas vesicles (GV). The well-characterized species Halobacterium halobium and some GV+ revertants of GV- mutants of H. halobium produce large amounts of GV which have a spindlelike shape. Most other GV+ revertants of H. halobium GV- mutants and other recently characterized halobacterial wild-type strains possess GV with a cylindrical form. The number of intact particles in the latter isolates is only 10 to 30% of that of H. halobium. Analysis of GV envelope proteins (GVPs) by electrophoresis on phenol-acetic acid-urea gels showed that the GVP of the highly efficient GV-producing strains migrated faster than the GVP of the low-GV-producing strains. The relative molecular mass of the GVP was estimated to be 19 kilodaltons (kDa) for high-producing strains (GVP-A) and 20 kDa for low-producing strains (GVP-B). Amino acid sequence analysis of the first 40 amino acids of the N-terminal parts of GVP-A and GVP-B indicated that the two proteins differed in two defined positions. GVP-B, in relation to GVP-A, had Gly-7 and Val-28 always replaced by Ser-7 and Ile-28, respectively. These data suggest that at least two different gvp genes exist in H. halobium NRL. This was directly demonstrated by hybridization experiments with gvp-specific DNA probes. A fragment of plasmid pHH1 and a chromosomal fragment of H. halobium hybridized to the probes. Only a chromosomal fragment hybridized to the same gyp probes when both chromosomal and plasmid DNAs from the low-GV-producing halobacterial wild-type strains SB3 and GN101 were examined. These findings support the assumption that GVP-A is expressed by a pHH1-associated gvp gene and GVP-B by a chromosomal gvp gene.
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Affiliation(s)
- B Surek
- Institut für Genetik und Mikrobiologie, Universität Würzburg, Federal Republic of Germany
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30
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Pinette MF, Koch AL. Variability of the turgor pressure of individual cells of the gram-negative heterotroph Ancylobacter aquaticus. J Bacteriol 1987; 169:4737-42. [PMID: 3654582 PMCID: PMC213848 DOI: 10.1128/jb.169.10.4737-4742.1987] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Cells of Ancylobacter aquaticus were observed under phase microscopy in a chamber to which a measured pressure could be applied. The initial collapse pressure (Ca), i.e., the lowest pressure needed to collapse the most pressure-sensitive gas vesicles, was measured for 69 cells. The cells were taken from cultures in low-density balanced exponential growth, and the experiments were performed quickly so that the bacteria were in a uniform physiological state at the time of measurement. The turgor pressure, Pt, is the difference between the pressure, C, that would cause collapse of vesicles when removed from the cell and Ca. In this paper we focus on the variability of Pt from cell to cell. Part of the observed variability of Ca was due to the variability of the collapse pressure of individual vesicles (standard deviation [SD] = 90 kPa), but because there were about 100 vesicles per cell and because a change in refracted light after the fifth vesicle (approximately) collapsed probably could be detected by the human eye, the pressure would only have an SD of 18.6 kPa due to this type of sampling error. The observed SD of Pt was 42 kPa, indicating that turgor pressure did vary considerably from cell to cell. However, the turgor pressure was independent of cell size. Statistical analysis showed that Pt would decrease 6.9 kPa over a cell cycle, but with too large an SD (19.9 kPa) to be significant. This implies that the observed change in Pt over the cell cycle is not statistically significant.
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Affiliation(s)
- M F Pinette
- Biology Department, Indiana University, Bloomington 47405
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31
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Hayes PK, Walsby AE, Walker JE. Complete amino acid sequence of cyanobacterial gas-vesicle protein indicates a 70-residue molecule that corresponds in size to the crystallographic unit cell. Biochem J 1986; 236:31-6. [PMID: 3098234 PMCID: PMC1146782 DOI: 10.1042/bj2360031] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Gas vesicles of cyanobacteria are formed by a protein called 'gas-vesicle protein' (GVP). The complete amino acid sequence has been determined of GVP from Anabaena flos-aquae. It is 70 residues long and has an Mr of 7388. This corresponds to the size of the repeating unit cell demonstrated by X-ray crystallography of intact gas vesicles. Details of the sequence are related to the secondary beta-sheet structure of the protein and its contrasting hydrophilic and hydrophobic surfaces. Extensive amino acid sequences have also been determined for GVPs from two other cyanobacteria, species of Calothrix and Microcystis; they are highly homologous with that of Anabaena GVP. Electrophoretic analysis indicates that GVPs of different cyanobacteria form a variety of stable oligomers.
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32
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33
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Staley JT, Stanley PM. Potential commercial applications in aquatic microbiology. MICROBIAL ECOLOGY 1986; 12:79-100. [PMID: 24212459 DOI: 10.1007/bf02153224] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Affiliation(s)
- J T Staley
- Department of Microbiology and Immunology, University of Washington, 98195, Seattle, WA
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34
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Tandeau de Marsac N, Mazel D, Bryant DA, Houmard J. Molecular cloning and nucleotide sequence of a developmentally regulated gene from the cyanobacterium Calothrix PCC 7601: a gas vesicle protein gene. Nucleic Acids Res 1985; 13:7223-36. [PMID: 2997744 PMCID: PMC322040 DOI: 10.1093/nar/13.20.7223] [Citation(s) in RCA: 70] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Since the gas vesicle protein (GVP) is highly conserved among the different gas-vacuolate prokaryotes, a 29-mer oligonucleotide corresponding to a portion of the Anabaena flos-aquae GVP gene was synthesized and used to isolate the GVP structural gene from Calothrix PCC 7601 (= Fremyella diplosiphon). Gas vacuole production in this filamentous cyanobacterium is restricted to hormogonia which occur at a specific stage during the developmental cell cycle. The GVP gene (gvpA) was localized on a 709 bp HindIII-HincII fragment. Nucleotide sequence analysis revealed a 213 bp open reading frame whose deduced amino-acid sequence shows a very high homology with that of the Anabaena flos-aquae GVP. Assuming that the first methionine residue is proteolytically processed, the molecular mass of the Calothrix GVP is 7375 daltons. Sequences resembling the Escherichia coli consensus promoter were found upstream from the gvpA gene. The initiator codon of the gvpA gene is preceded by a polypurine sequence assumed to be the ribosome binding site. Southern hybridizations with a probe specific for the gvpA gene indicated that this gene is not plasmid-borne, and that another homologous gene is present in the Calothrix genome.
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35
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Paerl HW, Bland PT, Bowles ND, Haibach ME. Adaptation to High-Intensity, Low-Wavelength Light among Surface Blooms of the Cyanobacterium
Microcystis aeruginosa. Appl Environ Microbiol 1985; 49:1046-52. [PMID: 16346779 PMCID: PMC238502 DOI: 10.1128/aem.49.5.1046-1052.1985] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Natural populations of the nuisance bloom cyanobacterium
Microcystis aeruginosa
obtained from the eutrophic Neuse River, N.C., revealed optimal chlorophyll
a
-normalized photosynthetic rates and resistance to photoinhibition at surface photosynthetically active radiation (PAR) intensities. At saturating PAR levels these populations exhibited higher photosynthetic rates in quartz than in Pyrex vessels. Eucaryotic algal populations obtained from the same river failed to counteract photoinhibition. At saturating PAR levels, such populations generally yielded lower photosynthetic rates in quartz containers than they did in Pyrex containers. Cultivation of natural
Microcystis
populations under laboratory conditions led to physiologically distinct populations which had photoinhibitory characteristics similar to those of other cultured cyanobacterial and eucaryotic algae. Our findings indicate that (i) photosynthetic production among natural surface populations is best characterized and quantified in quartz rather than Pyrex incubation vessels; (ii) extrapolation of natural photoinhibitory trends from laboratory populations is highly subjective to culture and PAR histories and may yield contradictory results; and (iii) buoyant surface-dwelling populations, rather than exhibiting senescence, are poised at optimizing PAR utilization, thereby maintaining numerical dominance in eutrophic waters when physico-chemical conditions favor bloom formation.
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Affiliation(s)
- H W Paerl
- Institute of Marine Sciences, University of North Carolina, Morehead City, North Carolina 28557
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36
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Cyanobacterial carotenoids: their roles in maintaining optimal photosynthetic production among aquatic bloom forming genera. Oecologia 1984; 61:143-149. [PMID: 28309403 DOI: 10.1007/bf00396752] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/1983] [Indexed: 10/26/2022]
Abstract
Photoprotective and photosynthetic roles of carotenoid pigments (xanthophylls and β-carotene) were examined in the major bloom forming blue-green algal (cyanobacterial) genera, Anabaena, Aphanizomenon and Microcystis. Since these genera often reside as scums in surface waters, attention was given to the ability of carotenoids to counter potential photooxidation due to maximum near U.V. and visible radiation as well as O2 supersaturation, characterizing surface waters supporting blooms. In U.V.-transparent quartz incubation flasks it was shown that inhibition of carotenoid synthesis by diphenylamine led to rapid photooxidation among the above genera. When carotenoid synthesis was allowed to proceed, a high degree of resistance to photooxidation resulted. Prolonged exposure to near U.V. irradiation led to enhanced carotenoid synthesis relative to chlorophyll a, which extended viability. Carotenoid enhancement also increased chlorophyll a-specific photosynthetic O2 production. It is concluded that enhanced carotenoid synthesis observed during blooms serves at least two ecological functions, i) providing photoprotection and ii) increasing photosynthetic performance of surface cyanobacterial populations.
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37
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Fattom A, Shilo M. Hydrophobicity as an Adhesion Mechanism of Benthic Cyanobacteria. Appl Environ Microbiol 1984; 47:135-43. [PMID: 16346453 PMCID: PMC239625 DOI: 10.1128/aem.47.1.135-143.1984] [Citation(s) in RCA: 139] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The capacity of benthic cyanobacteria to adhere to solid substrates was examined in terms of their cell surface properties. By using a biphasic water-hydrocarbon test system, it was demonstrated that benthic cyanobacteria from divergent habitats were all hydrophobic, whereas all the planktonic cyanobacteria tested were hydrophilic. Divalent cations were found more efficient than monovalent cations in effecting the expression of hydrophobicity. Mechanical shearing of the cell surface, as well as chemical removal of the cell wall, demonstrated that the hydrophobicity was confined to the outer surface layers. The hydrophobic sites were distributed along the whole length of the cyanobacterial filament. Hydrophilic hormogonia of benthic cyanobacteria became hydrophobic within 48 h when grown in the light; chloramphenicol, 3(3,4-dichlorophenyl)1,1 dimethylurea, or incubation in the dark prevented this transition. Hydrophobicity of
Phormidium
filaments was masked in late stationary phase; this effect was removed by gentle washing.
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Affiliation(s)
- A Fattom
- Division of Microbial and Molecular Ecology, Life Sciences Institute, Hebrew University, Jerusalem, Israel
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38
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Walker JE, Walsby AE. Molecular weight of gas-vesicle protein from the planktonic cyanobacterium Anabaena flos-aquae and implications for structure of the vesicle. Biochem J 1983; 209:809-15. [PMID: 6409075 PMCID: PMC1154161 DOI: 10.1042/bj2090809] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The gas vesicle of the planktonic cyanobacterium Anabaena flos-aquae is a cylindrical shell made of protein enclosing a gas-filled space. Protein sequence analysis shows that the vesicle is made from a single protein. By gel electrophoresis and amino acid analysis its molecular weight was estimated to be 20 600. Taken with previously obtained X-ray data, a simple interpretation of its molecular structure is of the polypeptide snaking in six pairs of antiparallel chains, three in each layer. The molecule would repeat along the ribs of the vesicle at intervals of 3.4 nm.
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Remsen CC. Structural attributes of membraneous organelles in bacteria. INTERNATIONAL REVIEW OF CYTOLOGY 1982; 76:195-223. [PMID: 6749745 DOI: 10.1016/s0074-7696(08)61791-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Widdel F, Pfennig N. Sporulation and further nutritional characteristics of Desulfotomaculum acetoxidans. Arch Microbiol 1981; 129:401-2. [PMID: 7283637 DOI: 10.1007/bf00406471] [Citation(s) in RCA: 76] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Acetate-oxidizing sulfate-reducing bacteria of the Desulfotomaculum acetoxidans type have been enriched from animal manure, rumen content and dung contaminated freshwater habitats, indicating that they are primarily intestinal bacteria. Sporulation was observed only when acetate was the organic substrate; with butyrate, which allowed faster growth than acetate, spore formation never occurred. The cone-shaped highly refractile areas adjacent to the spores in spore-forming mother cells were shown to be gas vacuoles. Biotin was the only growth factor required by Desulfotomaculum acetoxidans strain 5575 in minimal media with sulfate and acetate or other organic substrates.
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Simon RD. Acrylamide gel electrophoresis of hydrophobic proteins: Gas vacuole protein. Electrophoresis 1980. [DOI: 10.1002/elps.1150010310] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Walsby A. The properties and buoyancy-providing role of gas vacuoles inTrichodesmiumEhrenberg. ACTA ACUST UNITED AC 1978. [DOI: 10.1080/00071617800650121] [Citation(s) in RCA: 38] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Simon RD. Halobacterium strain 5 contains a plasmid which is correlated with the presence of gas vacuoles. Nature 1978; 273:314-7. [PMID: 652039 DOI: 10.1038/273314a0] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Clark AE, Walsby AE. The development and vertical distribution of populations of gas-vacuolate bacteria in a eutrophic, monomictic lake. Arch Microbiol 1978. [DOI: 10.1007/bf00429110] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Konopka AE, Lara JC, Staley JT. Isolation and characterization of gas vesicles from Microcyclus aquaticus. Arch Microbiol 1977; 112:133-40. [PMID: 403898 DOI: 10.1007/bf00429325] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Intact gas vesicles of Microcyclus aquaticus S1 were isolated by using centrifugally accelerated flotation of vesicles and molecular sieve chromatography. Isolated gas vesicles were cylindrical organelles with biconical ends and measured 250x100nm. The gas vesicle membrane was composed almost entirely of protein; neither lipid nor carbohydrate was detected, although one mole of phosphate per mole of protein was found. Amino acid analysis indicated that the protein contained 54.6% hydrophobic amino acid residues, lacked sulfur-containing amino acids, and had a low aromatic amino acid content. The protein subunit composition of the vesicles was determined by gel electrophoresis in (i) 0.1% sodium dodecyl sulfate at pH 9.0 and (ii) 5 M urea at pH 2.0. The membrane appeared to consist of one protein subunit of MW 50000 daltons. Charge isomers of this subunit were not detected on urea gels. Antiserum prepared against purified gas vesicles of M. aquaticus S1 crossreacted with the gas vesicles of all other gas vacuolate strains of M. aquaticus, as well as those of Prosthecomicrobium pneumaticum, Nostoc muscorum, and Anabaena flos-aquae, indicating that the gas vesicles of these widely divergent organisms have some antigenic determinants in common.
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Weathers PJ, Jost M, Lamport DT. The gas vacuole membrane of Microcystis aeruginosa. A partial amino acid sequence. Arch Biochem Biophys 1977; 178:226-44. [PMID: 402115 DOI: 10.1016/0003-9861(77)90188-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Absence of gas vesicle protein in a mutant of Anabaena flos-aquae. Arch Microbiol 1977. [DOI: 10.1007/bf00410779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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