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Piccini C, Martínez de la Escalera G, Segura AM, Croci C, Kruk C. The Microcystis-microbiome interactions: origins of the colonial lifestyle. FEMS Microbiol Ecol 2024; 100:fiae035. [PMID: 38499447 PMCID: PMC10996927 DOI: 10.1093/femsec/fiae035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Revised: 02/21/2024] [Accepted: 03/16/2024] [Indexed: 03/20/2024] Open
Abstract
Species of the Microcystis genus are the most common bloom-forming toxic cyanobacteria worldwide. They belong to a clade of unicellular cyanobacteria whose ability to reach high biomasses during blooms is linked to the formation of colonies. Colonial lifestyle provides several advantages under stressing conditions of light intensity, ultraviolet light, toxic substances and grazing. The progression from a single-celled organism to multicellularity in Microcystis has usually been interpreted as individual phenotypic responses of the cyanobacterial cells to the environment. Here, we synthesize current knowledge about Microcystis colonial lifestyle and its role in the organism ecology. We then briefly review the available information on Microcystis microbiome and propose that changes leading from single cells to colonies are the consequence of specific and tightly regulated signals between the cyanobacterium and its microbiome through a biofilm-like mechanism. The resulting colony is a multi-specific community of interdependent microorganisms.
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Affiliation(s)
- Claudia Piccini
- Departamento de Microbiología, Centro de Investigación en Ciencias Ambientales, Instituto de Investigaciones Biológicas Clemente Estable. Av. Italia 3318, Montevideo 11600, Uruguay
| | - Gabriela Martínez de la Escalera
- Departamento de Microbiología, Centro de Investigación en Ciencias Ambientales, Instituto de Investigaciones Biológicas Clemente Estable. Av. Italia 3318, Montevideo 11600, Uruguay
| | - Angel M Segura
- Modelización Estadística de Datos e Inteligencia Artificial, Centro Universitario Regional del Este, Universidad de la República. Ruta nacional Nº9 intersección con ruta Nº15, Uruguay
| | - Carolina Croci
- Departamento de Microbiología, Centro de Investigación en Ciencias Ambientales, Instituto de Investigaciones Biológicas Clemente Estable. Av. Italia 3318, Montevideo 11600, Uruguay
| | - Carla Kruk
- Modelización Estadística de Datos e Inteligencia Artificial, Centro Universitario Regional del Este, Universidad de la República. Ruta nacional Nº9 intersección con ruta Nº15, Uruguay
- Sección Limnología, Instituto de Ecología y Ciencias Ambientales, Facultad de Ciencias, Universidad de la República. Iguá 4225, Montevideo 11400, Uruguay
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2
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Conradi FD, Mullineaux CW, Wilde A. The Role of the Cyanobacterial Type IV Pilus Machinery in Finding and Maintaining a Favourable Environment. Life (Basel) 2020; 10:life10110252. [PMID: 33114175 PMCID: PMC7690835 DOI: 10.3390/life10110252] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 10/18/2020] [Accepted: 10/21/2020] [Indexed: 12/11/2022] Open
Abstract
Type IV pili (T4P) are proteinaceous filaments found on the cell surface of many prokaryotic organisms and convey twitching motility through their extension/retraction cycles, moving cells across surfaces. In cyanobacteria, twitching motility is the sole mode of motility properly characterised to date and is the means by which cells perform phototaxis, the movement towards and away from directional light sources. The wavelength and intensity of the light source determine the direction of movement and, sometimes in concert with nutrient conditions, act as signals for some cyanobacteria to form mucoid multicellular assemblages. Formation of such aggregates or flocs represents an acclimation strategy to unfavourable environmental conditions and stresses, such as harmful light conditions or predation. T4P are also involved in natural transformation by exogenous DNA, secretion processes, and in cellular adaptation and survival strategies, further cementing the role of cell surface appendages. In this way, cyanobacteria are finely tuned by external stimuli to either escape unfavourable environmental conditions via phototaxis, exchange genetic material, and to modify their surroundings to fit their needs by forming multicellular assemblies.
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Affiliation(s)
- Fabian D. Conradi
- School of Biological and Chemical Sciences, Queen Mary University of London, London E1 4NS, UK; (F.D.C.); (C.W.M.)
| | - Conrad W. Mullineaux
- School of Biological and Chemical Sciences, Queen Mary University of London, London E1 4NS, UK; (F.D.C.); (C.W.M.)
| | - Annegret Wilde
- Institute of Biology III, University of Freiburg, Schänzlestr. 1, 79104 Freiburg; Germany
- Correspondence:
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3
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Esteves-Ferreira AA, Inaba M, Obata T, Fort A, Fleming GTA, Araújo WL, Fernie AR, Sulpice R. A Novel Mechanism, Linked to Cell Density, Largely Controls Cell Division in Synechocystis. PLANT PHYSIOLOGY 2017; 174:2166-2182. [PMID: 28646084 PMCID: PMC5543973 DOI: 10.1104/pp.17.00729] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 06/20/2017] [Indexed: 05/28/2023]
Abstract
Many studies have investigated the various genetic and environmental factors regulating cyanobacterial growth. Here, we investigated the growth and metabolism of Synechocystis sp. PCC 6803 under different nitrogen sources, light intensities, and CO2 concentrations. Cells grown on urea showed the highest growth rates. However, for all conditions tested, the daily growth rates in batch cultures decreased steadily over time, and stationary phase was obtained with similar cell densities. Unexpectedly, metabolic and physiological analyses showed that growth rates during log phase were not controlled primarily by the availability of photoassimilates. Further physiological investigations indicated that nutrient limitation, quorum sensing, light quality, and light intensity (self-shading) were not the main factors responsible for the decrease in the growth rate and the onset of the stationary phase. Moreover, cell division rates in fed-batch cultures were positively correlated with the dilution rates. Hence, not only light, CO2, and nutrients can affect growth but also a cell-cell interaction. Accordingly, we propose that cell-cell interaction may be a factor responsible for the gradual decrease of growth rates in batch cultures during log phase, culminating with the onset of stationary phase.
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Affiliation(s)
- Alberto A Esteves-Ferreira
- National University of Ireland-Galway, Plant Systems Biology Laboratory, Plant and AgriBiosciences Research Centre, School of Natural Sciences, Galway, Ireland
- CAPES Foundation, Ministry of Education of Brazil, Brasilia DF 70040 020, Brazil
| | - Masami Inaba
- National University of Ireland-Galway, Plant Systems Biology Laboratory, Plant and AgriBiosciences Research Centre, School of Natural Sciences, Galway, Ireland
| | - Toshihiro Obata
- Central Metabolism Laboratory, Department of Molecular Physiology, Max Planck Institute of Molecular Plant Physiology, Max Planck Society, 14476 Potsdam-Golm, Germany
| | - Antoine Fort
- National University of Ireland-Galway, Genetics and Biotechnology Research Laboratory, Plant and AgriBiosciences Research Centre, School of Natural Sciences, Galway, Ireland
| | - Gerard T A Fleming
- National University of Ireland-Galway, Microbiology, School of Natural Sciences, Galway, Ireland
| | - Wagner L Araújo
- Max-Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-900 Vicosa, Minas Gerais, Brazil
| | - Alisdair R Fernie
- Central Metabolism Laboratory, Department of Molecular Physiology, Max Planck Institute of Molecular Plant Physiology, Max Planck Society, 14476 Potsdam-Golm, Germany
| | - Ronan Sulpice
- National University of Ireland-Galway, Plant Systems Biology Laboratory, Plant and AgriBiosciences Research Centre, School of Natural Sciences, Galway, Ireland
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4
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Sure S, Torriero AAJ, Gaur A, Li LH, Chen Y, Tripathi C, Adholeya A, Ackland ML, Kochar M. Identification and topographical characterisation of microbial nanowires in Nostoc punctiforme. Antonie Van Leeuwenhoek 2016; 109:475-80. [PMID: 26754102 DOI: 10.1007/s10482-015-0644-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 12/30/2015] [Indexed: 11/28/2022]
Abstract
Extracellular pili-like structures (PLS) produced by cyanobacteria have been poorly explored. We have done detailed topographical and electrical characterisation of PLS in Nostoc punctiforme PCC 73120 using transmission electron microscopy (TEM) and conductive atomic force microscopy (CAFM). TEM analysis showed that N. punctiforme produces two separate types of PLS differing in their length and diameter. The first type of PLS are 6-7.5 nm in diameter and 0.5-2 µm in length (short/thin PLS) while the second type of PLS are ~20-40 nm in diameter and more than 10 µm long (long/thick PLS). This is the first study to report long/thick PLS in N. punctiforme. Electrical characterisation of these two different PLS by CAFM showed that both are electrically conductive and can act as microbial nanowires. This is the first report to show two distinct PLS and also identifies microbial nanowires in N. punctiforme. This study paves the way for more detailed investigation of N. punctiforme nanowires and their potential role in cell physiology and symbiosis with plants.
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Affiliation(s)
- Sandeep Sure
- TERI-Deakin Nanobiotechnology Centre, TERI Gram, The Energy and Resources Institute, Gual Pahari, Gurgaon-Faridabad Road, Gurgaon, Haryana, 122 001, India
| | - Angel A J Torriero
- Centre for Cellular & Molecular Biology, Deakin University, 221 Burwood Highway, Burwood, Melbourne, VIC, 3125, Australia
| | - Aditya Gaur
- TERI-Deakin Nanobiotechnology Centre, TERI Gram, The Energy and Resources Institute, Gual Pahari, Gurgaon-Faridabad Road, Gurgaon, Haryana, 122 001, India
| | - Lu Hua Li
- Institute for Frontier Materials, Deakin University, Geelong Waurn Ponds Campus, Geelong, VIC, 3216, Australia
| | - Ying Chen
- Institute for Frontier Materials, Deakin University, Geelong Waurn Ponds Campus, Geelong, VIC, 3216, Australia
| | - Chandrakant Tripathi
- TERI-Deakin Nanobiotechnology Centre, TERI Gram, The Energy and Resources Institute, Gual Pahari, Gurgaon-Faridabad Road, Gurgaon, Haryana, 122 001, India
| | - Alok Adholeya
- TERI-Deakin Nanobiotechnology Centre, TERI Gram, The Energy and Resources Institute, Gual Pahari, Gurgaon-Faridabad Road, Gurgaon, Haryana, 122 001, India
| | - M Leigh Ackland
- Centre for Cellular & Molecular Biology, Deakin University, 221 Burwood Highway, Burwood, Melbourne, VIC, 3125, Australia
| | - Mandira Kochar
- TERI-Deakin Nanobiotechnology Centre, TERI Gram, The Energy and Resources Institute, Gual Pahari, Gurgaon-Faridabad Road, Gurgaon, Haryana, 122 001, India.
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5
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Kolman MA, Salerno GL. Sucrose in bloom-forming cyanobacteria: loss and gain of genes involved in its biosynthesis. Environ Microbiol 2015; 18:439-49. [PMID: 26913819 DOI: 10.1111/1462-2920.13071] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Revised: 09/19/2015] [Accepted: 09/24/2015] [Indexed: 11/30/2022]
Abstract
Bloom-forming cyanobacteria are widely distributed in freshwater ecosystems. To cope with salinity fluctuations, cyanobacteria synthesize compatible solutes, such as sucrose, to maintain the intracellular osmotic balance. The screening of cyanobacterial genomes revealed that homologues to sucrose metabolism-related genes only occur in few bloom-forming strains, mostly belonging to Nostocales and Stigonematales orders. Remarkably, among Chroococcales and Oscillatoriales strains, homologues were only found in M. aeruginosa PCC 7806 and Leptolyngbya boryana PCC 6306, suggesting a massive loss of sucrose metabolism in bloom-forming strains of these orders. After a complete functional characterization of sucrose genes in M. aeruginosa PCC 7806, we showed that sucrose metabolism depends on the expression of a gene cluster that defines a transcriptional unit, unique among all sucrose-containing cyanobacteria. It was also demonstrated that the expression of the encoding genes of sucrose-related proteins is stimulated by salt. In view of its ancestral origin in cyanobacteria, the fact that most bloom-forming strains lack sucrose metabolism indicates that the genes involved might have been lost during evolution. However, in a particular strain, like M. aeruginosa PCC 7806, sucrose synthesis genes were probably regained by horizontal gene transfer, which could be hypothesized as a response to salinity fluctuations.
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Affiliation(s)
- María A Kolman
- Instituto de Investigaciones en Biodiversidad y Biotecnología (INBIOTEC-CONICET), Fundación para Investigaciones Biológicas Aplicadas (FIBA), Vieytes 3103, Mar del Plata, 7600, Argentina
| | - Graciela L Salerno
- Instituto de Investigaciones en Biodiversidad y Biotecnología (INBIOTEC-CONICET), Fundación para Investigaciones Biológicas Aplicadas (FIBA), Vieytes 3103, Mar del Plata, 7600, Argentina
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Sure S, Torriero AAJ, Gaur A, Li LH, Chen Y, Tripathi C, Adholeya A, Ackland ML, Kochar M. Inquisition of Microcystis aeruginosa and Synechocystis nanowires: characterization and modelling. Antonie van Leeuwenhoek 2015; 108:1213-25. [PMID: 26319534 DOI: 10.1007/s10482-015-0576-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 08/24/2015] [Indexed: 10/23/2022]
Abstract
Identification of extracellular conductive pilus-like structures (PLS) i.e. microbial nanowires has spurred great interest among scientists due to their potential applications in the fields of biogeochemistry, bioelectronics, bioremediation etc. Using conductive atomic force microscopy, we identified microbial nanowires in Microcystis aeruginosa PCC 7806 which is an aerobic, photosynthetic microorganism. We also confirmed the earlier finding that Synechocystis sp. PCC 6803 produces microbial nanowires. In contrast to the use of highly instrumented continuous flow reactors for Synechocystis reported earlier, we identified simple and optimum culture conditions which allow increased production of nanowires in both test cyanobacteria. Production of these nanowires in Synechocystis and Microcystis were found to be sensitive to the availability of carbon source and light intensity. These structures seem to be proteinaceous in nature and their diameter was found to be 4.5-7 and 8.5-11 nm in Synechocystis and M. aeruginosa, respectively. Characterization of Synechocystis nanowires by transmission electron microscopy and biochemical techniques confirmed that they are type IV pili (TFP) while nanowires in M. aeruginosa were found to be similar to an unnamed protein (GenBank : CAO90693.1). Modelling studies of the Synechocystis TFP subunit i.e. PilA1 indicated that strategically placed aromatic amino acids may be involved in electron transfer through these nanowires. This study identifies PLS from Microcystis which can act as nanowires and supports the earlier hypothesis that microbial nanowires are widespread in nature and play diverse roles.
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Affiliation(s)
- Sandeep Sure
- TERI-Deakin Nanobiotechnology Centre, TERI Gram, The Energy and Resources Institute, Gual Pahari, Gurgaon Faridabad Road, Gurgaon, 122 001, Haryana, India
| | - Angel A J Torriero
- Centre for Cellular and Molecular Biology, Deakin University, 221 Burwood Highway, Burwood, Melbourne, VIC, 3125, Australia
| | - Aditya Gaur
- TERI-Deakin Nanobiotechnology Centre, TERI Gram, The Energy and Resources Institute, Gual Pahari, Gurgaon Faridabad Road, Gurgaon, 122 001, Haryana, India
| | - Lu Hua Li
- Institute for Frontier Materials, Deakin University, Geelong Waurn Ponds Campus, Geelong, VIC, 3216, Australia
| | - Ying Chen
- Institute for Frontier Materials, Deakin University, Geelong Waurn Ponds Campus, Geelong, VIC, 3216, Australia
| | - Chandrakant Tripathi
- TERI-Deakin Nanobiotechnology Centre, TERI Gram, The Energy and Resources Institute, Gual Pahari, Gurgaon Faridabad Road, Gurgaon, 122 001, Haryana, India
| | - Alok Adholeya
- TERI-Deakin Nanobiotechnology Centre, TERI Gram, The Energy and Resources Institute, Gual Pahari, Gurgaon Faridabad Road, Gurgaon, 122 001, Haryana, India
| | - M Leigh Ackland
- Centre for Cellular and Molecular Biology, Deakin University, 221 Burwood Highway, Burwood, Melbourne, VIC, 3125, Australia
| | - Mandira Kochar
- TERI-Deakin Nanobiotechnology Centre, TERI Gram, The Energy and Resources Institute, Gual Pahari, Gurgaon Faridabad Road, Gurgaon, 122 001, Haryana, India.
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7
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Schuergers N, Wilde A. Appendages of the cyanobacterial cell. Life (Basel) 2015; 5:700-15. [PMID: 25749611 PMCID: PMC4390875 DOI: 10.3390/life5010700] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2015] [Revised: 02/12/2015] [Accepted: 02/25/2015] [Indexed: 12/29/2022] Open
Abstract
Extracellular non-flagellar appendages, called pili or fimbriae, are widespread in gram-negative bacteria. They are involved in many different functions, including motility, adhesion, biofilm formation, and uptake of DNA. Sequencing data for a large number of cyanobacterial genomes revealed that most of them contain genes for pili synthesis. However, only for a very few cyanobacteria structure and function of these appendages have been analyzed. Here, we review the structure and function of type IV pili in Synechocystis sp. PCC 6803 and analyze the distribution of type IV pili associated genes in other cyanobacteria. Further, we discuss the role of the RNA-chaperone Hfq in pilus function and the presence of genes for the chaperone-usher pathway of pilus assembly in cyanobacteria.
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Affiliation(s)
- Nils Schuergers
- University of Freiburg, Institute of Biology III, Schänzlestr. 1, 79104 Freiburg, Germany.
| | - Annegret Wilde
- University of Freiburg, Institute of Biology III, Schänzlestr. 1, 79104 Freiburg, Germany.
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8
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Penn K, Wang J, Fernando SC, Thompson JR. Secondary metabolite gene expression and interplay of bacterial functions in a tropical freshwater cyanobacterial bloom. THE ISME JOURNAL 2014; 8:1866-78. [PMID: 24646695 PMCID: PMC4139720 DOI: 10.1038/ismej.2014.27] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Revised: 01/08/2014] [Accepted: 01/17/2014] [Indexed: 11/09/2022]
Abstract
Cyanobacterial harmful algal blooms (cyanoHABs) appear to be increasing in frequency on a global scale. The Cyanobacteria in blooms can produce toxic secondary metabolites that make freshwater dangerous for drinking and recreation. To characterize microbial activities in a cyanoHAB, transcripts from a eutrophic freshwater reservoir in Singapore were sequenced for six samples collected over one day-night period. Transcripts from the Cyanobacterium Microcystis dominated all samples and were accompanied by at least 533 genera primarily from the Cyanobacteria, Proteobacteria, Bacteroidetes and Actinobacteria. Within the Microcystis population, abundant transcripts were from genes for buoyancy, photosynthesis and synthesis of the toxin microviridin, suggesting that these are necessary for competitive dominance in the Reservoir. During the day, Microcystis transcripts were enriched in photosynthesis and energy metabolism while at night enriched pathways included DNA replication and repair and toxin biosynthesis. Microcystis was the dominant source of transcripts from polyketide and non-ribosomal peptide synthase (PKS and NRPS, respectively) gene clusters. Unexpectedly, expression of all PKS/NRPS gene clusters, including for the toxins microcystin and aeruginosin, occurred throughout the day-night cycle. The most highly expressed PKS/NRPS gene cluster from Microcystis is not associated with any known product. The four most abundant phyla in the reservoir were enriched in different functions, including photosynthesis (Cyanobacteria), breakdown of complex organic molecules (Proteobacteria), glycan metabolism (Bacteroidetes) and breakdown of plant carbohydrates, such as cellobiose (Actinobacteria). These results provide the first estimate of secondary metabolite gene expression, functional partitioning and functional interplay in a freshwater cyanoHAB.
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Affiliation(s)
- Kevin Penn
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Jia Wang
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Samodha C Fernando
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Janelle R Thompson
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
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Harel M, Weiss G, Daniel E, Wilenz A, Hadas O, Sukenik A, Sedmak B, Dittmann E, Braun S, Kaplan A. Casting a net: fibres produced by Microcystis sp. in field and laboratory populations. ENVIRONMENTAL MICROBIOLOGY REPORTS 2012; 4:342-349. [PMID: 23760798 DOI: 10.1111/j.1758-2229.2012.00339.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The reasons for the apparent dominance of the toxic cyanobacterium Microcystis sp., reflected by its massive blooms in many fresh water bodies, are poorly understood. We show that in addition to a large array of secondary metabolites, some of which are toxic to eukaryotes, Microcystis sp. secretes large amounts of fibrous exopolysaccharides that form extremely long fibres several millimetres in length. This phenomenon was detected in field and laboratory cultures of various Microcystis strains. In addition, we have identified and characterized three of the proteins associated with the fibres and the genes encoding them in Microcystis sp. PCC 7806 but were unable to completely delete them from its genome. Phylogenetic analysis of the most abundant one, designated IPF-469, showed its presence only in cyanobacteria. Its closest relatives were detected in Synechocystis sp. PCC 6803 and in Cyanothece sp. strains; in the latter the genomic organization of the IPF-469 was highly conserved. IPF-469 and the other two proteins identified here, a haloperoxidase and a haemolysin-type calcium-binding protein, may be part of the fibres secretion pathway. The biological role of the fibres in Microcystis sp. is discussed.
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Affiliation(s)
- Moshe Harel
- The Alexander Silberman Institute of Life Sciences, Edmond J. Safra Campus, Givat Ram, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel The Yigal Allon Kinneret Limnological Laboratory, Israel Oceanographic and Limnological Research, PO Box 447, Migdal 14950, Israel Department of Genetic Toxicology and Cancer Biology, National Institute of Biology, Ljubljana, Slovenia Institute of Biochemistry and Biology, University of Potsdam, 14476 Golm, Germany
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10
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Nakasugi K, Svenson CJ, Neilan BA. The competence gene, comF, from Synechocystis sp. strain PCC 6803 is involved in natural transformation, phototactic motility and piliation. MICROBIOLOGY-SGM 2007; 152:3623-3631. [PMID: 17159215 DOI: 10.1099/mic.0.29189-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The gene slr0388 was previously annotated to encode a hypothetical protein in Synechocystis sp. strain PCC 6803. When a positively phototactic strain of this cyanobacterium was insertionally inactivated at slr0388, the mutants were not transformable, and appeared to aggregate as a result of increased bundling of type IV pili. Also, these mutants were rendered non-phototactic compared to the wild-type. Quantitative real-time PCR revealed a 3.5-fold increase in pilA1 transcript levels in the mutant over wild-type cells, while there were no changes in the level of pilT1 and comA transcripts. Supernatant from mutant liquid culture contained more PilA1 protein, confirmed by mass spectrometric analysis, compared to the wild-type cells, which corresponded to the increase in pilA1 transcripts. The increase in PilA1 subunits may contribute to the bundling morphology of pili that was observed, which in turn may act to retard DNA uptake by hindering the retraction of pili. This gene is therefore proposed to be designated comF, as it possesses a phosphoribosyltransferase domain, a distinguishing feature of other ComF proteins of naturally transformable heterotrophic bacteria. This report is the second of a competence-related gene from Synechocystis sp. strain PCC 6803, the product of which does not show homology to other well-studied type IV pili proteins.
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MESH Headings
- Amino Acid Sequence
- Bacterial Proteins/genetics
- Bacterial Proteins/physiology
- DNA Transposable Elements
- Fimbriae Proteins/biosynthesis
- Fimbriae, Bacterial/genetics
- Fimbriae, Bacterial/physiology
- Fimbriae, Bacterial/ultrastructure
- Light
- Microscopy, Electron, Scanning
- Microscopy, Electron, Transmission
- Molecular Sequence Data
- Movement
- Mutagenesis, Insertional
- RNA, Bacterial/biosynthesis
- RNA, Messenger/biosynthesis
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Alignment
- Synechocystis/genetics
- Synechocystis/physiology
- Synechocystis/ultrastructure
- Transformation, Bacterial
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Affiliation(s)
- Kenlee Nakasugi
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Charles J Svenson
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Brett A Neilan
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia
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11
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Nakasugi K, Alexova R, Svenson CJ, Neilan BA. Functional analysis of PilT from the toxic cyanobacterium Microcystis aeruginosa PCC 7806. J Bacteriol 2006; 189:1689-97. [PMID: 17172325 PMCID: PMC1855755 DOI: 10.1128/jb.01640-06] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The evolution of the microcystin toxin gene cluster in phylogenetically distant cyanobacteria has been attributed to recombination, inactivation, and deletion events, although gene transfer may also be involved. Since the microcystin-producing Microcystis aeruginosa PCC 7806 is naturally transformable, we have initiated the characterization of its type IV pilus system, involved in DNA uptake in many bacteria, to provide a physiological focus for the influence of gene transfer in microcystin evolution. The type IV pilus genes pilA, pilB, pilC, and pilT were shown to be expressed in M. aeruginosa PCC 7806. The purified PilT protein yielded a maximal ATPase activity of 37.5 +/- 1.8 nmol P(i) min(-1) mg protein(-1), with a requirement for Mg(2+). Heterologous expression indicated that it could complement the pilT mutant of Pseudomonas aeruginosa, but not that of the cyanobacterium Synechocystis sp. strain PCC 6803, which was unexpected. Differences in two critical residues between the M. aeruginosa PCC 7806 PilT (7806 PilT) and the Synechocystis sp. strain PCC 6803 PilT proteins affected their theoretical structural models, which may explain the nonfunctionality of 7806 PilT in its cyanobacterial counterpart. Screening of the pilT gene in toxic and nontoxic strains of Microcystis was also performed.
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Affiliation(s)
- Kenlee Nakasugi
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia
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