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Kramer BJ, Jankowiak JG, Nanjappa D, Harke MJ, Gobler CJ. Nitrogen and phosphorus significantly alter growth, nitrogen fixation, anatoxin-a content, and the transcriptome of the bloom-forming cyanobacterium, Dolichospermum. Front Microbiol 2022; 13:955032. [PMID: 36160233 PMCID: PMC9490380 DOI: 10.3389/fmicb.2022.955032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 08/19/2022] [Indexed: 11/27/2022] Open
Abstract
While freshwater cyanobacteria are traditionally thought to be limited by the availability of phosphorus (P), fixed nitrogen (N) supply can promote the growth and/or toxin production of some genera. This study characterizes how growth on N2 (control), nitrate (NO3 -), ammonium (NH4 +), and urea as well as P limitation altered the growth, toxin production, N2 fixation, and gene expression of an anatoxin-a (ATX-A) - producing strain of Dolichospermum sp. 54. The transcriptomes of fixed N and P-limited cultures differed significantly from those of fixed N-deplete, P-replete (control) cultures, while the transcriptomes of P-replete cultures amended with either NH4 + or NO3 - were not significantly different relative to those of the control. Growth rates of Dolichospermum (sp. 54) were significantly higher when grown on fixed N relative to without fixed N; growth on NH4 + was also significantly greater than growth on NO3 -. NH4 + and urea significantly lowered N2 fixation and nifD gene transcript abundance relative to the control while cultures amended with NO3 - exhibited N2 fixation and nifD gene transcript abundance that was not different from the control. Cultures grown on NH4 + exhibited the lowest ATX-A content per cell and lower transcript abundance of genes associated ATX-A synthesis (ana), while the abundance of transcripts of several ana genes were highest under fixed N and P - limited conditions. The significant negative correlation between growth rate and cellular anatoxin quota as well as the significantly higher number of transcripts of ana genes in cultures deprived of fixed N and P relative to P-replete cultures amended with NH4 + suggests ATX-A was being actively synthesized under P limitation. Collectively, these findings indicate that management strategies that do not regulate fixed N loading will leave eutrophic water bodies vulnerable to more intense and toxic (due to increased biomass) blooms of Dolichospermum.
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Affiliation(s)
- Benjamin J. Kramer
- School of Marine and Atmospheric Sciences, Stony Brook University, Southampton, NY, United States
| | | | - Deepak Nanjappa
- School of Marine and Atmospheric Sciences, Stony Brook University, Southampton, NY, United States
| | - Matthew J. Harke
- Gloucester Marine Genomics Institute, Gloucester, MA, United States
| | - Christopher J. Gobler
- School of Marine and Atmospheric Sciences, Stony Brook University, Southampton, NY, United States
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Wang ZQ, Zhang CC. A tRNA t 6A modification system contributes to the sensitivity towards the toxin β-N-methylamino-L-alanine (BMAA) in the cyanobacterium Anabaena sp. PCC 7120. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2022; 245:106121. [PMID: 35180454 DOI: 10.1016/j.aquatox.2022.106121] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 01/24/2022] [Accepted: 02/12/2022] [Indexed: 06/14/2023]
Abstract
Cyanobacteria are oxygen-evolving photosynthetic autotrophs essential for nutrient cycling in the environment. They possess multiple control mechanisms for their cellular activities in order to adapt to the environment. While protein translation is essential for cell survival and adaptation, the regulation and the flexibility of this process are poorly understood in cyanobacteria. β-N-methylamino-L-alanine (BMAA), an amino acid analog proposed as an environmental neurotoxin, is highly toxic to the filamentous diazotrophic cyanobacterium Anabaena PCC 7120. In this study, through genetic analysis of BMAA-resistant mutants, we demonstrate that the system responsible for modification of ANN-decoding tRNAs with N(6)-threonylcarbamoyl adenosine (t6A) is involved in BMAA sensitivity through the control of translation. Both BMAA and inactivation of the t6A biosynthesis pathway affect translational fidelity and ribosome assembly. However, the two factors display either additive effects on translational elongation, or attenuate each other over translational fidelity or the resistance/sensitivity to antibiotics that inhibit different steps of the translational process. BMAA has a broad effect on translation and transcription, and once BMAA enters the cells, the presence of the t6A biosynthesis pathway increases the sensitivity of the cells towards this toxin. BMAA-resistant mutants screening is an effective method for getting insight into the toxic mechanisms of BMAA. In addition, BMAA is a useful tool for probing translational flexibility of cyanobacteria, and the characterization of the corresponding resistant mutants should help us to reveal translational mechanism allowing cyanobacteria to adapt to changing environments.
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Affiliation(s)
- Zi-Qian Wang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, Hubei, People's Republic of China; University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Cheng-Cai Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, Hubei, People's Republic of China; Institute WUT-AMU, Aix-Marseille University and Wuhan University of Technology, Wuhan, Hubei, People's Republic of China.
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Pelletier A, Freton C, Gallay C, Trouve J, Cluzel C, Franz-Wachtel M, Macek B, Jault JM, Grangeasse C, Guiral S. The Tyrosine-Autokinase UbK Is Required for Proper Cell Growth and Cell Morphology of Streptococcus pneumoniae. Front Microbiol 2019; 10:1942. [PMID: 31551943 PMCID: PMC6733980 DOI: 10.3389/fmicb.2019.01942] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 08/07/2019] [Indexed: 12/11/2022] Open
Abstract
Protein phosphorylation is a key post-translational modification required for many cellular functions of the bacterial cell. Recently, we identified a new protein-kinase, named UbK, in Bacillus subtilis that belongs to a new family of protein-kinases widespread in bacteria. In this study, we analyze the function of UbK in Streptococcus pneumoniae. We show that UbK displays a tyrosine-kinase activity and autophosphorylates on a unique tyrosine in vivo. To get insights into its cellular role, we constructed a set of pneumococcal ubk mutants. Using conventional and electron microscopy, we show that the ubk deficient strain, as well as an ubk catalytic dead mutant, display both severe cell-growth and cell-morphology defects. The same defects are observed with a mutant mimicking permanent phosphorylation of UbK whereas they are not detected for a mutant mimicking defective autophosphorylation of UbK. Moreover, we find that UbK phosphorylation promotes its ability to hydrolyze ATP. These observations show that the hydrolysis of ATP by UbK serves not only for its autophosphorylation but also for a distinct purpose essential for the optimal cell growth and cell-morphogenesis of the pneumococcus. We thus propose a model in which the autophosphorylation/dephosphorylation of UbK regulates its cellular function through a negative feedback loop.
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Affiliation(s)
- Anaïs Pelletier
- Molecular Microbiology and Structural Biochemistry, UMR 5086 CNRS/Université Lyon 1, Lyon, France
| | - Céline Freton
- Molecular Microbiology and Structural Biochemistry, UMR 5086 CNRS/Université Lyon 1, Lyon, France
| | - Clément Gallay
- Molecular Microbiology and Structural Biochemistry, UMR 5086 CNRS/Université Lyon 1, Lyon, France
| | - Jennyfer Trouve
- Molecular Microbiology and Structural Biochemistry, UMR 5086 CNRS/Université Lyon 1, Lyon, France
| | - Caroline Cluzel
- Laboratoire de Biologie Tissulaire et d'Ingénierie Thérapeutique, UMR 5305 CNRS/Université Lyon 1, Lyon, France
| | | | - Boris Macek
- Proteome Center Tübingen, University of Tübingen, Tübingen, Germany
| | - Jean-Michel Jault
- Molecular Microbiology and Structural Biochemistry, UMR 5086 CNRS/Université Lyon 1, Lyon, France
| | - Christophe Grangeasse
- Molecular Microbiology and Structural Biochemistry, UMR 5086 CNRS/Université Lyon 1, Lyon, France
| | - Sébastien Guiral
- Molecular Microbiology and Structural Biochemistry, UMR 5086 CNRS/Université Lyon 1, Lyon, France
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Abstract
The filamentous cyanobacterium Anabaena can form heterocysts specialized in N2 fixation, mostly through a cascade of transcriptional activation in response to the nitrogen starvation signal 2-oxoglutarate. It is reported now that a transcription repressor, CalA, acts as a safety device to prevent heterocyst development under certain conditions where the 2-oxoglutarate level may touch the threshold to trigger unnecessary initiation of heterocyst development. Such a control may increase the fitness of Anabaena under a constantly changing environment.
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Elhai J, Khudyakov I. Ancient association of cyanobacterial multicellularity with the regulator HetR and an RGSGR pentapeptide-containing protein (PatX). Mol Microbiol 2018; 110:931-954. [PMID: 29885033 DOI: 10.1111/mmi.14003] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/04/2018] [Indexed: 12/14/2022]
Abstract
One simple model to explain biological pattern postulates the existence of a stationary regulator of differentiation that positively affects its own expression, coupled with a diffusible suppressor of differentiation that inhibits the regulator's expression. The first has been identified in the filamentous, heterocyst-forming cyanobacterium, Anabaena PCC 7120 as the transcriptional regulator, HetR and the second as the small protein, PatS, which contains a critical RGSGR motif that binds to HetR. HetR is present in almost all filamentous cyanobacteria, but only a subset of heterocyst-forming strains carry proteins similar to PatS. We identified a third protein, PatX that also carries the RGSGR motif and is coextensive with HetR. Amino acid sequences of PatX contain two conserved regions: the RGSGR motif and a hydrophobic N-terminus. Within 69 nt upstream from all instances of the gene is a DIF1 motif correlated in Anabaena with promoter induction in developing heterocysts, preceded in heterocyst-forming strains by an apparent NtcA-binding site, associated with regulation by nitrogen-status. Consistent with a role in the simple model, PatX is expressed dependent on HetR and acts to inhibit differentiation. The acquisition of the PatX/HetR pair preceded the appearance of both PatS and heterocysts, dating back to the beginnings of multicellularity.
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Affiliation(s)
- Jeff Elhai
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, VA, 23284, USA
| | - Ivan Khudyakov
- All-Russia Research Institute for Agricultural Microbiology, Saint-Petersburg, 196608, Russia
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Handford JI, Ize B, Buchanan G, Butland GP, Greenblatt J, Emili A, Palmer T. Conserved network of proteins essential for bacterial viability. J Bacteriol 2009; 191:4732-49. [PMID: 19376873 PMCID: PMC2715707 DOI: 10.1128/jb.00136-09] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2009] [Accepted: 04/07/2009] [Indexed: 12/28/2022] Open
Abstract
The yjeE, yeaZ, and ygjD genes are highly conserved in the genomes of eubacteria, and ygjD orthologs are also found throughout the Archaea and eukaryotes. In this study, we have constructed conditional expression strains for each of these genes in the model organism Escherichia coli K12. We show that each gene is essential for the viability of E. coli under laboratory growth conditions. Growth of the conditional strains under nonpermissive conditions results in dramatic changes in cell ultrastructure. Deliberate repression of the expression of yeaZ results in cells with highly condensed nucleoids, while repression of yjeE and ygjD expression results in at least a proportion of very enlarged cells with an unusual peripheral distribution of DNA. Each of the three conditional expression strains can be complemented by multicopy clones harboring the rstA gene, which encodes a two-component-system response regulator, strongly suggesting that these proteins are involved in the same essential cellular pathway. The results of bacterial two-hybrid experiments show that YeaZ can interact with both YjeE and YgjD but that YgjD is the preferred interaction partner. The results of in vitro experiments indicate that YeaZ mediates the proteolysis of YgjD, suggesting that YeaZ and YjeE act as regulators to control the activity of this protein. Our results are consistent with these proteins forming a link between DNA metabolism and cell division.
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Affiliation(s)
- Jennifer I Handford
- Department of Molecular Microbiology, John Innes Centre, Norwich, United Kingdom
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Ni S, Benning MM, Smola MJ, Feldmann EA, Kennedy MA. Crystal structure of Npun_R1517, a putative negative regulator of heterocyst differentiation fromNostoc punctiformePCC 73102. Proteins 2009; 74:794-8. [DOI: 10.1002/prot.22308] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Known Bioactive Small Molecules Probe the Function of a Widely Conserved but Enigmatic Bacterial ATPase, YjeE. ACTA ACUST UNITED AC 2008; 15:1287-95. [DOI: 10.1016/j.chembiol.2008.10.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2008] [Revised: 09/30/2008] [Accepted: 10/14/2008] [Indexed: 11/22/2022]
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