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Hill AM, Salmond GPC. Microbial gas vesicles as nanotechnology tools: exploiting intracellular organelles for translational utility in biotechnology, medicine and the environment. MICROBIOLOGY (READING, ENGLAND) 2020; 166:501-509. [PMID: 32324529 PMCID: PMC7376271 DOI: 10.1099/mic.0.000912] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 03/21/2020] [Indexed: 12/12/2022]
Abstract
A range of bacteria and archaea produce gas vesicles as a means to facilitate flotation. These gas vesicles have been purified from a number of species and their applications in biotechnology and medicine are reviewed here. Halobacterium sp. NRC-1 gas vesicles have been engineered to display antigens from eukaryotic, bacterial and viral pathogens. The ability of these recombinant nanoparticles to generate an immune response has been quantified both in vitro and in vivo. These gas vesicles, along with those purified from Anabaena flos-aquae and Bacillus megaterium, have been developed as an acoustic reporter system. This system utilizes the ability of gas vesicles to retain gas within a stable, rigid structure to produce contrast upon exposure to ultrasound. The susceptibility of gas vesicles to collapse when exposed to excess pressure has also been proposed as a biocontrol mechanism to disperse cyanobacterial blooms, providing an environmental function for these structures.
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Affiliation(s)
- Amy M. Hill
- Department of Biochemistry, Tennis Court Road, University of Cambridge, Cambridge, CB2 1QW, UK
| | - George P. C. Salmond
- Department of Biochemistry, Tennis Court Road, University of Cambridge, Cambridge, CB2 1QW, UK
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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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Lakshmanan A, Farhadi A, Nety SP, Lee-Gosselin A, Bourdeau RW, Maresca D, Shapiro MG. Molecular Engineering of Acoustic Protein Nanostructures. ACS NANO 2016; 10:7314-22. [PMID: 27351374 PMCID: PMC6058967 DOI: 10.1021/acsnano.6b03364] [Citation(s) in RCA: 96] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Ultrasound is among the most widely used biomedical imaging modalities, but has limited ability to image specific molecular targets due to the lack of suitable nanoscale contrast agents. Gas vesicles-genetically encoded protein nanostructures isolated from buoyant photosynthetic microbes-have recently been identified as nanoscale reporters for ultrasound. Their unique physical properties give gas vesicles significant advantages over conventional microbubble contrast agents, including nanoscale dimensions and inherent physical stability. Furthermore, as a genetically encoded material, gas vesicles present the possibility that the nanoscale mechanical, acoustic, and targeting properties of an imaging agent can be engineered at the level of its constituent proteins. Here, we demonstrate that genetic engineering of gas vesicles results in nanostructures with new mechanical, acoustic, surface, and functional properties to enable harmonic, multiplexed, and multimodal ultrasound imaging as well as cell-specific molecular targeting. These results establish a biomolecular platform for the engineering of acoustic nanomaterials.
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Affiliation(s)
- Anupama Lakshmanan
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA-91125, USA
| | - Arash Farhadi
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA-91125, USA
| | - Suchita P. Nety
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA-91125, USA
| | - Audrey Lee-Gosselin
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA-91125, USA
| | - Raymond W. Bourdeau
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA-91125, USA
| | - David Maresca
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA-91125, USA
| | - Mikhail G. Shapiro
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA-91125, USA
- Correspondence should be addressed to MGS: , Phone: 626-395-8588 or 617-835-0878, 1200 E. California Blvd, MC 210-41, Pasadena, CA 91125
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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: 29] [Impact Index Per Article: 3.6] [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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Becker S, Hayes PK, Walsby AE. Different gvpC length variants are transcribed within single filaments of the cyanobacterium Planktothrix rubescens. MICROBIOLOGY-SGM 2005; 151:59-67. [PMID: 15632425 DOI: 10.1099/mic.0.27402-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Transcripts of the gas vesicle genes gvpA and gvpC were detected in single filaments of the cyanobacterium Planktothrix rubescens using reverse transcription and quantitative real-time PCR. Primers were designed to amplify short sequences within gvpA and three length variants of gvpC. With genomic template DNA, and using Sybr Green to monitor product accumulation, similar amplification efficiencies were observed for each of these genes. The relative copy numbers of gvpC length variants in genomic DNA from five Planktothrix gas vesicle genotypes determined by real-time PCR were similar to those indicated by sequencing the gas vesicle gene clusters. The precipitation of gvp cDNA reverse-transcribed from cellular RNA from single filaments was required before amplification of the gene fragments; without this step it was not possible to detect the accumulation of the expected amplicons by dissociation analysis. Precipitation was also necessary to ensure the generation of product curves that allowed linear regression in an early stage of PCR, a prerequisite for the quantification of low-input cDNA amounts without the need for standard curves. This report shows that different gvpC length variants are transcribed within single Planktothrix filaments, both from laboratory cultures and from natural samples taken from Lake Zurich. This has implications for the efficiency of buoyancy provision by the possible production of gas vesicles of different strengths within individual cyanobacterial filaments. The hypothesis that post-transcriptional regulation may influence the type of protein (GvpC) present in gas vesicles is presented.
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Affiliation(s)
- Sven Becker
- School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK
| | - Paul K Hayes
- School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK
| | - Anthony E Walsby
- School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK
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8
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Mlouka A, Comte K, Castets AM, Bouchier C, Tandeau de Marsac N. The gas vesicle gene cluster from Microcystis aeruginosa and DNA rearrangements that lead to loss of cell buoyancy. J Bacteriol 2004; 186:2355-65. [PMID: 15060038 PMCID: PMC412153 DOI: 10.1128/jb.186.8.2355-2365.2004] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Microcystis aeruginosa is a planktonic unicellular cyanobacterium often responsible for seasonal mass occurrences at the surface of freshwater environments. An abundant production of intracellular structures, the gas vesicles, provides cells with buoyancy. A 8.7-kb gene cluster that comprises twelve genes involved in gas vesicle synthesis was identified. Ten of these are organized in two operons, gvpA(I)A(II)A(III)CNJX and gvpKFG, and two, gvpV and gvpW, are individually expressed. In an attempt to elucidate the basis for the frequent occurrence of nonbuoyant mutants in laboratory cultures, four gas vesicle-deficient mutants from two strains of M. aeruginosa, PCC 7806 and PCC 9354, were isolated and characterized. Their molecular analysis unveiled DNA rearrangements due to four different insertion elements that interrupted gvpN, gvpV, or gvpW or led to the deletion of the gvpA(I)-A(III) region. While gvpA, encoding the major gas vesicle structural protein, was expressed in the gvpN, gvpV, and gvpW mutants, immunodetection revealed no corresponding GvpA protein. Moreover, the absence of a gas vesicle structure was confirmed by electron microscopy. This study brings out clues concerning the process driving loss of buoyancy in M. aeruginosa and reveals the requirement for gas vesicle synthesis of two newly described genes, gvpV and gvpW.
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Affiliation(s)
- Alyssa Mlouka
- Unité des Cyanobactéries (URA-CNRS 2172), Département de Microbiologie fondamentale et médicale, Institut Pasteur, 75724 Paris Cedex 15, France
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9
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Lim WJ, Park SR, Kim MK, An CL, Yun HJ, Hong SY, Kim EJ, Shin EC, Lee SW, Lim YP, Yun HD. Cloning and characterization of the glycogen branching enzyme gene existing in tandem with the glycogen debranching enzyme from Pectobacterium chrysanthemi PY35. Biochem Biophys Res Commun 2003; 300:93-101. [PMID: 12480526 DOI: 10.1016/s0006-291x(02)02763-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The glycogen branching enzyme gene (glgB) from Pectobacterium chrysanthemi PY35 was cloned, sequenced, and expressed in Escherichia coli. The glgB gene consisted of an open reading frame of 2196bp encoding a protein of 731 amino acids (calculated molecular weight of 83,859Da). The glgB gene is upstream of glgX and the ORF starts the ATG initiation codon and ends with the TGA stop codon at 2bp upstream of glgX. The enzyme was 43-69% sequence identical with other glycogen branching enzymes. The enzyme is the most similar to GlgB of E. coli and contained the four regions conserved among the alpha-amylase family. The glycogen branching enzyme (GlgB) was purified and the molecular weight of the enzyme was estimated to be 84kDa by SDS-PAGE. The glycogen branching enzyme was optimally active at pH 7 and 30 degrees C.
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Affiliation(s)
- Woo Jin Lim
- Division of Applied Life Science, Gyeongsang National University, Chinju 660-701, Republic of Korea
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Beard SJ, Handley BA, Walsby AE. Spontaneous mutations in gas vesicle genes of Planktothrix spp. affect gas vesicle production and critical pressure. FEMS Microbiol Lett 2002; 215:189-95. [PMID: 12399034 DOI: 10.1111/j.1574-6968.2002.tb11390.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Wild-type strains of the cyanobacterium Planktothrix rubescens have a cluster of gas vesicle (gvp) genes with repeats of alternating gvpA and gvpC. The gvpC occurs in three length variants, all with the same 3'-sequence, OmegaC. Spontaneous non-buoyant mutants had lost some of the alternating gvpAC copies and their gvpC genes had a novel 3'-end sequence, PsiC; additional gvpC genes terminating in this sequence were also found in the wild-type and representatives of other GV genotypes. Alleles of gvpC terminating in PsiC occurred only at the downstream ends of the gvpAC clusters investigated; all other gvpCs terminated in OmegaC. Mutants of strains with the GV3 genotype produced only 30-50% of the gas vesicles present in the wild-type; their gas vesicles had lower mean critical pressures (0.70-0.78 MPa) than those in the wild-type (1.05-1.10 MPa).
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Affiliation(s)
- Steven J Beard
- School of Biological Sciences, University of Bristol, Woodland Road, UK
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Albouy D, Castets AM, De Marsac NT. The gas vesicle gene (gvp) cluster of the cyanobacterium Pseudanabaena sp. strain PCC 6901. DNA SEQUENCE : THE JOURNAL OF DNA SEQUENCING AND MAPPING 2001; 12:337-44. [PMID: 11913779 DOI: 10.3109/10425170109084457] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
A gene cluster located downstream from gvpA in the cyanobacterium Pseudanabaena sp. strain PCC 6901 has been cloned and sequenced. The three genes, orf1, gvpN and gvpJ, are consecutive with no intergenic region. In contrast to GvpN and GvpJ, which share high similarity at the amino acid level with their counterparts in other cyanobacteria and halophilic archaea, Orf1 is only 29% identical to the C-terminal part of GvpC from Anabaena flos-aquae and its sequence organization is reminiscent of the halophilic archaeal GvpC.
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Affiliation(s)
- D Albouy
- Departement de Biochimie et Génétique Moléculaire, Unité des Cyanobactéries Microbienne, Paris, France
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12
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Offner S, Hofacker A, Wanner G, Pfeifer F. Eight of fourteen gvp genes are sufficient for formation of gas vesicles in halophilic archaea. J Bacteriol 2000; 182:4328-36. [PMID: 10894744 PMCID: PMC101952 DOI: 10.1128/jb.182.15.4328-4336.2000] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The minimal number of genes required for the formation of gas vesicles in halophilic archaea has been determined. Single genes of the 14 gvp genes present in the p-vac region on plasmid pHH1 of Halobacterium salinarum (p-gvpACNO and p-gvpDEFGHIJKLM) were deleted, and the remaining genes were tested for the formation of gas vesicles in Haloferax volcanii transformants. The deletion of six gvp genes (p-gvpCN, p-gvpDE, and p-gvpHI) still enabled the production of gas vesicles in H. volcanii. The gas vesicles formed in some of these gvp gene deletion transformants were altered in shape (Delta I, Delta C) or strength (Delta H) but still functioned as flotation devices. A minimal p-vac region (minvac) containing the eight remaining genes (gvpFGJKLM-gvpAO) was constructed and tested for gas vesicle formation in H. volcanii. The minvac transformants did not form gas vesicles; however, minvac/gvpJKLM double transformants contained gas vesicles seen as light refractile bodies by phase-contrast microscopy. Transcript analyses demonstrated that minvac transformants synthesized regular amounts of gvpA mRNA, but the transcripts derived from gvpFGJKLM were mainly short and encompassed only gvpFG(J), suggesting that the gvpJKLM genes were not sufficiently expressed. Since gvpAO and gvpFGJKLM are the only gvp genes present in minvac/JKLM transformants containing gas vesicles, these gvp genes represent the minimal set required for gas vesicle formation in halophilic archaea. Homologs of six of these gvp genes are found in Anabaena flos-aquae, and homologs of all eight minimal halobacterial gvp genes are present in Bacillus megaterium and in the genome of Streptomyces coelicolor.
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Affiliation(s)
- S Offner
- Institut für Mikrobiologie und Genetik, Technische Universität Darmstadt, D-64287 Darmstadt, Germany
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Beard SJ, Davis PA, Iglesias-Rodrı Guez D, Skulberg OM, Walsby AE. Gas vesicle genes in Planktothrix spp. from Nordic lakes: strains with weak gas vesicles possess a longer variant of gvpC. MICROBIOLOGY (READING, ENGLAND) 2000; 146 ( Pt 8):2009-2018. [PMID: 10931905 DOI: 10.1099/00221287-146-8-2009] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In cyanobacteria of the genus Planktothrix:, there are three length variants of gvpC, the gene that encodes the outer protein of the gas vesicle. Sequence analyses indicated that the three allelic variants of gvpC differ principally in the presence or absence of a 99 nt and a 213 nt section. Strains with the new variant, gvpC(28), which encodes a 28 kDa form of GvpC, produce gas vesicles that collapse at the relatively low critical pressure (p(c)) of 0.61-0.75 MPa. The authors have identified 12 classes of gvp genotypes that differ in the number and arrangement of alternating gvpA-gvpC genes and in the presence of OmegaC, a fragment of gvpC. The gvpC(28) gene was found to be the most common variant of gvpC amongst 71 strains of Planktothrix: isolated from Nordic lakes: 34 strains contained only gvpC(28); 22 strains, which possessed only the shorter gvpC(20) gene, produced gas vesicles with a higher p(c) of 0.76-0.91 MPa; and 15 strains, which possessed both gvpC(20) and gvpC(28), also produced the stronger gas vesicles. Genotypes with only the gvpC(28) genes were more common amongst green Planktothrix: strains (33 out of 38) than red strains (one out of 33). It is suggested that there is competition between the strains producing the two types of gas vesicles, with the stronger forms favoured in lakes deeper than 60 m, in which the combination of cell turgor pressure and hydrostatic pressure can collapse the weaker gas vesicles. The fact that none of the Nordic lakes are deeper than 67 m would explain the absence of the gvpC(16)-containing strains that produce even narrower gas vesicles of p(c) 1.0-1.2 MPa, which are common in the much deeper Lake Zürich.
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Affiliation(s)
- S J Beard
- School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK1
| | - P A Davis
- School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK1
| | - D Iglesias-Rodrı Guez
- School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK1
| | - O M Skulberg
- Norwegian Institute for Water Research, PO Box 173 Kjelsas, N-0411 Oslo, Norway2
| | - A E Walsby
- School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK1
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Beard SJ, Handley BA, Hayes PK, Walsby AE. The diversity of gas vesicle genes in Planktothrix rubescens from Lake Zürich. MICROBIOLOGY (READING, ENGLAND) 1999; 145 ( Pt 10):2757-68. [PMID: 10537197 DOI: 10.1099/00221287-145-10-2757] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Part of the gas vesicle gene cluster was amplified by PCR from three strains of Planktothrix rubescens isolated from Lake Zürich, Switzerland. Each contains multiple alternating copies of gvpA and gvpC. All of the gvpA sequences in the different strains are identical. There are two types of gvpC: gvpC20, of length 516 bp, encodes a 20 kDa protein of 172 amino acid residues (whose N-terminal amino acid sequence is homologous with the sequence of GvpC in Planktothrix [Oscillatoria] agardhii); gvpC16, of length 417 bp, encodes a 16 kDa protein of 139 amino acid residues that differs in lacking an internal 33-residue section. An untranslated 72 bp fragment from the 3' end of gvpC, designated omegaC, is also present in some strains. The two types of gvpC and presence of omegaC could be distinguished by the different lengths of PCR amplification products obtained using pairs of oligonucleotide primers homologous to internal sequences in gvpC and gvpA. Three genotype classes were found: GV1, containing only gvpC20; GV2, containing gvpC20 and omegaC; and GV3, containing gvpC16, gvpC20 and omegaC. Subclasses of GV2 and GV3 contained either one or two copies of omegaC. The accompanying paper by D. I. Bright & A. E. Walsby (Microbiology 145, 2769-2775) shows that strains of the GV3 genotype produce gas vesicles with a higher critical pressure than those of GV1 and GV2. A PCR survey of 185 clonal cultures of P. rubescens isolated from Lake Zürich revealed that 3 isolates were of genotype GV1, 73 were of GV2 and 109 were of GV3. The PCR technique was used to distinguish the gas vesicle genotype, and thence the associated critical-pressure phenotype, of single filaments selected from lakewater samples. Sequence analysis of the 16S rDNA and of regions within the operons encoding phycoerythrin, phycocyanin and Rubisco confirmed that these strains of Planktothrix form a tight phylogenetic group.
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Affiliation(s)
- S J Beard
- School of Biological Sciences, University of Bristol, UK
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15
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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: 46] [Impact Index Per Article: 1.8] [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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Li N, Cannon MC. Gas vesicle genes identified in Bacillus megaterium and functional expression in Escherichia coli. J Bacteriol 1998; 180:2450-8. [PMID: 9573198 PMCID: PMC107188 DOI: 10.1128/jb.180.9.2450-2458.1998] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Gas vesicles are intracellular, protein-coated, and hollow organelles found in cyanobacteria and halophilic archaea. They are permeable to ambient gases by diffusion and provide buoyancy, enabling cells to move upwards in liquid to access oxygen and/or light. In halobacteria, gas vesicle production is encoded in a 9-kb cluster of 14 genes (4 of known function). In cyanobacteria, the number of genes involved has not been determined. We now report the cloning and sequence analysis of an 8,142-bp cluster of 15 putative gas vesicle genes (gvp) from Bacillus megaterium VT1660 and their functional expression in Escherichia coli. Evidence includes homologies by sequence analysis to known gas vesicle genes, the buoyancy phenotype of E. coli strains that carry this gvp gene cluster, the presence of pressure-sensitive, refractile bodies in phase-contrast microscopy, structural details in phase-contrast microscopy, structural details in direct interference-contrast microscopy, and shape and size revealed by transmission electron microscopy. In B. megaterium, the gvp region carries a cluster of 15 putative genes arranged in one orientation; they are open reading frame 1 and gvpA, -P, -Q, -B, -R, -N, -F, -G, -L, -S, -K, -J, -T, and -U, of which the last 11 genes, in a 5.7-kb gene cluster, are the maximum required for gas vesicle synthesis and function in E. coli. To our knowledge, this is the first example of a functional gas vesicle gene cluster in nonaquatic bacteria and the first example of the interspecies transfer of genes resulting in the synthesis of a functional organelle.
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Affiliation(s)
- N Li
- Department of Microbiology, University of Massachusetts, Amherst 01003, USA
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Kinsman R, Hayes PK. Genes encoding proteins homologous to halobacterial Gvps N, J, K, F & L are located downstream of gvpC in the cyanobacterium Anabaena flos-aquae. DNA SEQUENCE : THE JOURNAL OF DNA SEQUENCING AND MAPPING 1997; 7:97-106. [PMID: 9063646 DOI: 10.3109/10425179709020156] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Only two gas vesicle genes have been previously identified in the cyanobacteria, gvpA and gvpC, both of which encode structural gas vesicle proteins. Analysis of the nucleotide sequence immediately downstream of gvpC in the cyanobacterium Anabaena flos-aquae has revealed the presence of 4 ORFs (open reading frames) the products of which share significant homology with a number of the gene products derived from halobacterial gvp gene clusters. In halobacteria the gas vesicle gene clusters consist of 14 genes involved in gas vesicle synthesis and assembly. The product of Anabaena ORF 1, located immediately downstream of gvpC is homologous to halobacterial GvpNs. For the remaining ORFs the predicted gene products show homology to both GvpJ and GvpA for ORF 2, to GvpK and GvpA for ORF 3, and to both GvpF and GvpL for ORF 4.
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Affiliation(s)
- R Kinsman
- School of Biological Sciences, University of Bristol, U.K
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Offner S, Wanner G, Pfeifer F. Functional studies of the gvpACNO operon of Halobacterium salinarium reveal that the GvpC protein shapes gas vesicles. J Bacteriol 1996; 178:2071-8. [PMID: 8606186 PMCID: PMC177907 DOI: 10.1128/jb.178.7.2071-2078.1996] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Gas vesicle (Vac) synthesis in Halobacterium salinarium PHH1 involves the expression of the plasmid pHH1-encoded vac (p-vac) region consisting of 14 different gvp genes that are arranged in two clusters, p-gvpACNO and, oriented in the direction opposite to that of gvpA, p-gvpDEFGHIJKLM. The p-gvpACNO region was analyzed at the transcriptional and functional levels in H. salinarium and in Haloferax volcanii transformants containing subfragments of the p-vac region. The p-gvpACNO genes were transcribed as several mRNAs: the 270-nucleotide (nt) p-gvpA transcript, encoding the major structural protein, occurred in large amounts, and minor amounts of three different readthrough transcripts (p-gvpACN, and p-gvpACNO mRNA) were found. In addition, the p-gvpO gene gave rise to two separate mRNA species: a 550-nt mRNA starting at the ATG and spanning the entire reading frame and a 420-nt RNA encompassing the second half of the p-gvpO gene. The requirement of p-gvpC, p-gvpN, and p-gvpO gene expression for gas vesicle synthesis was assessed by transformation experiments using the VAC- species Haloferax volcanii as the recipient. A delta C transformant, harboring the p-vac region with a deletion of the p-gvpC gene, produced large amounts of irregularly shaped gas vesicles. A shape-forming function of p-GvpC was demonstrated by complementation of the delta C transformant with the p-gvpC gene, resulting in wild-type-shaped gas vesicles. In the delta N transformant, the level of gas vesicle synthesis was very low, indicating that the p-GvpN protein is not required for gas vesicle assembly but may enhance gas vesicle synthesis. The p-gvpN deletion did not affect accumulation of p-gvpACO mRNA but reduced the separate p-gvpO transcription. The delta O transformant was Vac- and had a strongly decreased level of p-gvpACN mRNAs, demonstrating that the p-GvpO protein is required for gas vesicle synthesis and may affect transcription of this DNA region.
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Affiliation(s)
- S Offner
- Institut für Mikrobiologie und Genetik, Technische Hochschule Darmstadt, Germany
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