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Wang ZQ, Yang Y, Zhang JY, Zeng X, Zhang CC. Global translational control by the transcriptional repressor TrcR in the filamentous cyanobacterium Anabaena sp. PCC 7120. Commun Biol 2023; 6:643. [PMID: 37322092 PMCID: PMC10272220 DOI: 10.1038/s42003-023-05012-9] [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: 02/03/2023] [Accepted: 06/02/2023] [Indexed: 06/17/2023] Open
Abstract
Transcriptional and translational regulations are important mechanisms for cell adaptation to environmental conditions. In addition to house-keeping tRNAs, the genome of the filamentous cyanobacterium Anabaena sp. strain PCC 7120 (Anabaena) has a long tRNA operon (trn operon) consisting of 26 genes present on a megaplasmid. The trn operon is repressed under standard culture conditions, but is activated under translational stress in the presence of antibiotics targeting translation. Using the toxic amino acid analog β-N-methylamino-L-alanine (BMAA) as a tool, we isolated and characterized several BMAA-resistance mutants from Anabaena, and identified one gene of unknown function, all0854, named as trcR, encoding a transcription factor belonging to the ribbon-helix-helix (RHH) family. We provide evidence that TrcR represses the expression of the trn operon and is thus the missing link between the trn operon and translational stress response. TrcR represses the expression of several other genes involved in translational control, and is required for maintaining translational fidelity. TrcR, as well as its binding sites, are highly conserved in cyanobacteria, and its functions represent an important mechanism for the coupling of the transcriptional and translational regulations in cyanobacteria.
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Affiliation(s)
- Zi-Qian Wang
- State Key Laboratory of Freshwater Ecology and Biotechnology and Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, 430072, People's Republic of China.
- University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China.
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
| | - Yiling Yang
- State Key Laboratory of Freshwater Ecology and Biotechnology and Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, 430072, People's Republic of China
| | - Ju-Yuan Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology and Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, 430072, People's Republic of China
| | - Xiaoli Zeng
- State Key Laboratory of Freshwater Ecology and Biotechnology and Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, 430072, People's Republic of China
| | - Cheng-Cai Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology and Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, 430072, People's Republic of China.
- Institute AMU-WUT, Aix-Marseille Université and Wuhan University of Technology, Wuhan, Hubei, People's Republic of China.
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Li A, Liu J, Qiu J, Wang G, Zheng X, Ji Y, Yan G, Zhao P, Wu X, Yan W, Zhang L, Li M, Fu Y. Cell cycle of microalga Isochrysis galbana arrested by neurotoxin β-N-methylamino-l-alanine and corresponding molecular mechanisms. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 874:162445. [PMID: 36848993 DOI: 10.1016/j.scitotenv.2023.162445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Revised: 02/20/2023] [Accepted: 02/20/2023] [Indexed: 06/18/2023]
Abstract
The phycotoxin β-N-methylamino-l-alanine (BMAA) has attracted attention due to its risks to marine organisms and human health. In this study, approximately 85 % of synchronized cells of the marine microalga Isochrysis galbana were arrested at the cell cycle G1 phase by BMAA at 6.5 μM for a 24-h exposure. The concentration of chlorophyll a (Chl a) gradually decreased, while the maximum quantum yield of PSII (Fv/Fm), the maximum relative electron transport rate (rETRmax), light utilization efficiency (α) and half-saturated light irradiance (Ik) reduced early and recovered gradually in I. galbana exposed to BMAA in 96-h batch cultures. Transcriptional expression of I. galbana analyzed at 10, 12, and 16 h disclosed multiple mechanisms of BMAA to suppress the microalgal growth. Production of ammonia and glutamate was limited by the down-regulation of nitrate transporters, glutamate synthase, glutamine synthetase, cyanate hydrolase, and formamidase. Diverse extrinsic proteins related to PSII, PSI, cytochrome b6f complex, and ATPase were influenced by BMAA at transcriptional level. Suppression of the DNA replication and mismatch repair pathways increased the accumulation of misfolded proteins, which was reflected by the up-regulated expression of proteasome to accelerate proteolysis. This study improves our understanding of the chemical ecology impacts of BMAA in marine ecosystems.
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Affiliation(s)
- Aifeng Li
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China; Key Laboratory of Marine Environment and Ecology, Ocean University of China, Ministry of Education, Qingdao 266100, China.
| | - Jianwei Liu
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Jiangbing Qiu
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China; Key Laboratory of Marine Environment and Ecology, Ocean University of China, Ministry of Education, Qingdao 266100, China
| | - Guixiang Wang
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Xianyao Zheng
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Ying Ji
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Guowang Yan
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Peng Zhao
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Xizhen Wu
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Wenhui Yan
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Lei Zhang
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Min Li
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Yilei Fu
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
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Li A, Yan Y, Qiu J, Yan G, Zhao P, Li M, Ji Y, Wang G, Meng F, Li Y, Metcalf JS, Banack SA. Putative biosynthesis mechanism of the neurotoxin β-N-methylamino-L-alanine in marine diatoms based on a transcriptomics approach. JOURNAL OF HAZARDOUS MATERIALS 2023; 441:129953. [PMID: 36116313 DOI: 10.1016/j.jhazmat.2022.129953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 08/29/2022] [Accepted: 09/06/2022] [Indexed: 06/15/2023]
Abstract
The neurotoxin β-N-methylamino-L-alanine (BMAA) has been presumed as an environmental cause of human neurodegenerative disorders, such as Alzheimer's disease. Marine diatoms Thalassiosira minima are demonstrated here to produce BMAA-containing proteins in axenic culture while the isomer diaminobutyric acid was bacterially produced. In the co-culture with Cyanobacterium aponinum, diatom growth was inhibited but the biosynthesis of BMAA-containing proteins was stimulated up to seven times higher than that of the control group by cell-cell interactions. The stimulation effect was not caused by the cyanobacterial filtrate. Nitrogen deprivation also doubled the BMAA content of T. minima cells. Transcriptome analysis of the diatom in mixed culture revealed that pathways involved in T. minima metabolism and cellular functions were mainly influenced, including KEGG pathways valine and leucine/isoleucine degradation, endocytosis, pantothenate and CoA biosynthesis, and SNARE interactions in vesicular transport. Based on the expression changes of genes related to protein biosynthesis, it was hypothesized that ubiquitination and autophagy suppression, and limited COPII vesicles transport accuracy and efficiency were responsible for biosynthesis of BMAA-containing proteins in T. minima. This study represents a first application of transcriptomics to investigate the biological processes associated with BMAA biosynthesis in diatoms.
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Affiliation(s)
- Aifeng Li
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China; Key Laboratory of Marine Environment and Ecology, Ocean University of China, Ministry of Education, Qingdao 266100, China.
| | - Yeju Yan
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Jiangbing Qiu
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China; Key Laboratory of Marine Environment and Ecology, Ocean University of China, Ministry of Education, Qingdao 266100, China
| | - Guowang Yan
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Peng Zhao
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Min Li
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Ying Ji
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Guixiang Wang
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Fanping Meng
- College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China; Key Laboratory of Marine Environment and Ecology, Ocean University of China, Ministry of Education, Qingdao 266100, China
| | - Yang Li
- Guangdong Provincial Key Laboratory of Healthy and Safe Aquaculture, College of Life Science, South China Normal University, West 55 of Zhongshan Avenue, Guangzhou 510631, China
| | - James S Metcalf
- Brain Chemistry Labs, Institute for Ethnomedicine, PO Box 3464, Jackson, WY 83001, USA
| | - Sandra A Banack
- Brain Chemistry Labs, Institute for Ethnomedicine, PO Box 3464, Jackson, WY 83001, USA
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Non-Proteinogenic Amino Acid β-N-Methylamino-L-Alanine (BMAA): Bioactivity and Ecological Significance. Toxins (Basel) 2022; 14:toxins14080539. [PMID: 36006201 PMCID: PMC9414260 DOI: 10.3390/toxins14080539] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Revised: 07/28/2022] [Accepted: 08/04/2022] [Indexed: 11/21/2022] Open
Abstract
Research interest in a non-protein amino acid β-N-methylamino-L-alanine (BMAA) arose due to the discovery of a connection between exposure to BMAA and the occurrence of neurodegenerative diseases. Previous reviews on this topic either considered BMAA as a risk factor for neurodegenerative diseases or focused on the problems of detecting BMAA in various environmental samples. Our review is devoted to a wide range of fundamental biological problems related to BMAA, including the molecular mechanisms of biological activity of BMAA and the complex relationships between producers of BMAA and the environment in various natural ecosystems. At the beginning, we briefly recall the most important facts about the producers of BMAA (cyanobacteria, microalgae, and bacteria), the pathways of BMAA biosynthesis, and reliable methods of identification of BMAA. The main distinctive feature of our review is a detailed examination of the molecular mechanisms underlying the toxicity of BMAA to living cells. A brand new aspect, not previously discussed in any reviews, is the effect of BMAA on cyanobacterial cells. These recent studies, conducted using transcriptomics and proteomics, revealed potent regulatory effects of BMAA on the basic metabolism and cell development of these ancient photoautotrophic prokaryotes. Exogenous BMAA strongly influences cell differentiation and primary metabolic processes in cyanobacteria, such as nitrogen fixation, photosynthesis, carbon fixation, and various biosynthetic processes involving 2-oxoglutarate and glutamate. Cyanobacteria were found to be more sensitive to exogenous BMAA under nitrogen-limited growth conditions. We suggest a hypothesis that this toxic diaminoacid can be used by phytoplankton organisms as a possible allelopathic tool for controlling the population of cyanobacterial cells during a period of intense competition for nitrogen and other resources in various ecosystems.
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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: 0.5] [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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Koksharova OA, Butenko IO, Pobeguts OV, Safronova NA, Govorun VM. β-N-Methylamino-L-Alanine (BMAA) Causes Severe Stress in Nostoc sp. PCC 7120 Cells under Diazotrophic Conditions: A Proteomic Study. Toxins (Basel) 2021; 13:325. [PMID: 33946501 PMCID: PMC8147232 DOI: 10.3390/toxins13050325] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 04/07/2021] [Accepted: 04/28/2021] [Indexed: 12/24/2022] Open
Abstract
Non-proteinogenic neurotoxic amino acid β-N-methylamino-L-alanine (BMAA) is synthesized by cyanobacteria, diatoms, and dinoflagellates, and is known to be a causative agent of human neurodegenerative diseases. Different phytoplankton organisms' ability to synthesize BMAA could indicate the importance of this molecule in the interactions between microalgae in nature. We were interested in the following: what kinds of mechanisms underline BMAA's action on cyanobacterial cells in different nitrogen supply conditions. Herein, we present a proteomic analysis of filamentous cyanobacteria Nostoc sp. PCC 7120 cells that underwent BMAA treatment in diazotrophic conditions. In diazotrophic growth conditions, to survive, cyanobacteria can use only biological nitrogen fixation to obtain nitrogen for life. Note that nitrogen fixation is an energy-consuming process. In total, 1567 different proteins of Nostoc sp. PCC 7120 were identified by using LC-MS/MS spectrometry. Among them, 123 proteins belonging to different functional categories were selected-due to their notable expression differences-for further functional analysis and discussion. The presented proteomic data evidences that BMAA treatment leads to very strong (up to 80%) downregulation of α (NifD) and β (NifK) subunits of molybdenum-iron protein, which is known to be a part of nitrogenase. This enzyme is responsible for catalyzing nitrogen fixation. The genes nifD and nifK are under transcriptional control of a global nitrogen regulator NtcA. In this study, we have found that BMAA impacts in a total of 22 proteins that are under the control of NtcA. Moreover, BMAA downregulates 18 proteins that belong to photosystems I or II and light-harvesting complexes; BMAA treatment under diazotrophic conditions also downregulates five subunits of ATP synthase and enzyme NAD(P)H-quinone oxidoreductase. Therefore, we can conclude that the disbalance in energy and metabolite amounts leads to severe intracellular stress that induces the upregulation of stress-activated proteins, such as starvation-inducible DNA-binding protein, four SOS-response enzymes, and DNA repair enzymes, nine stress-response enzymes, and four proteases. The presented data provide new leads into the ecological impact of BMAA on microalgal communities that can be used in future investigations.
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Affiliation(s)
- Olga A. Koksharova
- Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, Leninskie Gory, 1-40, 119991 Moscow, Russia;
- Institute of Molecular Genetics of National Research Center “Kurchatov Institute”, Kurchatov Square, 2, 123182 Moscow, Russia
| | - Ivan O. Butenko
- Scientific-Research Institute of Physical-Chemical Medicine, 119435 Moscow, Russia; (I.O.B.); (O.V.P.); (V.M.G.)
| | - Olga V. Pobeguts
- Scientific-Research Institute of Physical-Chemical Medicine, 119435 Moscow, Russia; (I.O.B.); (O.V.P.); (V.M.G.)
| | - Nina A. Safronova
- Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, Leninskie Gory, 1-40, 119991 Moscow, Russia;
| | - Vadim M. Govorun
- Scientific-Research Institute of Physical-Chemical Medicine, 119435 Moscow, Russia; (I.O.B.); (O.V.P.); (V.M.G.)
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