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Zhou Z, Li Z, Zhong Y, Xu S, Li Z. Engineering of the Lrp/AsnC-type transcriptional regulator DecR as a genetically encoded biosensor for multilevel optimization of L-cysteine biosynthesis pathway in Escherichia coli. Biotechnol Bioeng 2024; 121:2133-2146. [PMID: 38634289 DOI: 10.1002/bit.28716] [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: 01/11/2024] [Revised: 03/27/2024] [Accepted: 04/08/2024] [Indexed: 04/19/2024]
Abstract
L-cysteine is an important sulfur-containing amino acid being difficult to produce by microbial fermentation. Due to the lack of high-throughput screening methods, existing genetically engineered bacteria have been developed by simply optimizing the expression of L-cysteine-related genes one by one. To overcome this limitation, in this study, a biosensor-based approach for multilevel biosynthetic pathway optimization of L-cysteine from the DecR regulator variant of Escherichia coli was applied. Through protein engineering, we obtained the DecRN29Y/C81E/M90Q/M99E variant-based biosensor with improved specificity and an 8.71-fold increase in dynamic range. Using the developed biosensor, we performed high-throughput screening of the constructed promoter and RBS combination library, and successfully obtained the optimized strain, which resulted in a 6.29-fold increase in L-cysteine production. Molecular dynamics (MD) simulations and electrophoretic mobility shift analysis (EMSA) showed that the N29Y/C81E/M90Q/M99E variant had enhanced induction activity. This enhancement may be due to the increased binding of the variant to DNA in the presence of L-cysteine, which enhances transcriptional activation. Overall, our biosensor-based strategy provides a promising approach for optimizing biosynthetic pathways at multiple levels. The successful implementation of this strategy demonstrates its potential for screening improved recombinant strains.
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Affiliation(s)
- Zhiyou Zhou
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Zonglin Li
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Yahui Zhong
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Shuai Xu
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Zhimin Li
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
- Shanghai Collaborative Innovation Center for Biomanufacturing Technology, Shanghai, China
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Zhou Z, Li Z, Li Z. Exploring the molecular mechanisms of Lrp/AsnC-type transcription regulator DecR, an L-cysteine-responsive feast/famine regulatory protein. Int J Biol Macromol 2024; 270:132519. [PMID: 38768919 DOI: 10.1016/j.ijbiomac.2024.132519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Revised: 05/16/2024] [Accepted: 05/17/2024] [Indexed: 05/22/2024]
Abstract
The Lrp/AsnC family of transcriptional regulators is commonly found in prokaryotes and is associated with the regulation of amino acid metabolism. However, it remains unclear how the L-cysteine-responsive Lrp/AsnC family regulator perceives and responds to L-cysteine. Here, we try to elucidate the molecular mechanism of the L-cysteine-responsive transcriptional regulator. Through 5'RACE and EMSA, we discovered a 15 bp incompletely complementary pair palindromic sequence essential for DecR binding, which differed slightly from the binding sequence of other Lrp/AsnC transcription regulators. Using alanine scanning, we identified the L-cysteine binding site on DecR and found that different Lrp/AsnC regulators adjust their binding pocket's side-chain residues to accommodate their specific effector. MD simulations were then conducted to explore how ligand binding influences the allosteric behavior of the protein. PCA and in silico docking revealed that ligand binding induced perturbations in the linker region, triggering conformational alterations and leading to the relocalization of the DNA-binding domains, enabling the embedding of the DNA-binding region of DecR into the DNA molecule, thereby enhancing DNA-binding affinity. Our findings can broaden the understanding of the recognition and regulatory mechanisms of the Lrp/AsnC-type transcription factors, providing a theoretical basis for further investigating the molecular mechanisms of other transcription factors.
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Affiliation(s)
- Zhiyou Zhou
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Zonglin Li
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China.
| | - Zhimin Li
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China; Shanghai Collaborative Innovation Center for Biomanufacturing Technology, 130 Meilong Road, Shanghai 200237, China.
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Trouillon J, Doubleday PF, Sauer U. Genomic footprinting uncovers global transcription factor responses to amino acids in Escherichia coli. Cell Syst 2023; 14:860-871.e4. [PMID: 37820729 DOI: 10.1016/j.cels.2023.09.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 09/01/2023] [Accepted: 09/19/2023] [Indexed: 10/13/2023]
Abstract
Our knowledge of transcriptional responses to changes in nutrient availability comes primarily from few well-studied transcription factors (TFs), often lacking an unbiased genome-wide perspective. Leveraging recent advances allowing bacterial genomic footprinting, we comprehensively mapped the genome-wide regulatory responses of Escherichia coli to exogenous leucine, methionine, alanine, and lysine. The global TF Lrp was found to individually sense three amino acids and mount three different target gene responses. Overall, 531 genes had altered RNA polymerase occupancy, and 32 TFs responded directly or indirectly to the presence of amino acids, including regulators of membrane and osmotic pressure homeostasis. About 70% of the detected TF-DNA interactions had not been reported before. We thus identified 682 previously unknown TF-binding locations, for a subset of which the involved TFs were identified by affinity purification. This comprehensive map of amino acid regulation illustrates the incompleteness of the known transcriptional regulation network, even in E. coli.
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Affiliation(s)
- Julian Trouillon
- Institute of Molecular Systems Biology, ETH Zürich, 8093 Zürich, Switzerland
| | - Peter F Doubleday
- Institute of Molecular Systems Biology, ETH Zürich, 8093 Zürich, Switzerland
| | - Uwe Sauer
- Institute of Molecular Systems Biology, ETH Zürich, 8093 Zürich, Switzerland.
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Krzyżanowska DM, Jabłońska M, Kaczyński Z, Czerwicka-Pach M, Macur K, Jafra S. Host-adaptive traits in the plant-colonizing Pseudomonas donghuensis P482 revealed by transcriptomic responses to exudates of tomato and maize. Sci Rep 2023; 13:9445. [PMID: 37296159 PMCID: PMC10256816 DOI: 10.1038/s41598-023-36494-6] [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: 01/24/2023] [Accepted: 06/05/2023] [Indexed: 06/12/2023] Open
Abstract
Pseudomonads are metabolically flexible and can thrive on different plant hosts. However, the metabolic adaptations required for host promiscuity are unknown. Here, we addressed this knowledge gap by employing RNAseq and comparing transcriptomic responses of Pseudomonas donghuensis P482 to root exudates of two plant hosts: tomato and maize. Our main goal was to identify the differences and the common points between these two responses. Pathways upregulated only by tomato exudates included nitric oxide detoxification, repair of iron-sulfur clusters, respiration through the cyanide-insensitive cytochrome bd, and catabolism of amino and/or fatty acids. The first two indicate the presence of NO donors in the exudates of the test plants. Maize specifically induced the activity of MexE RND-type efflux pump and copper tolerance. Genes associated with motility were induced by maize but repressed by tomato. The shared response to exudates seemed to be affected both by compounds originating from the plants and those from their growth environment: arsenic resistance and bacterioferritin synthesis were upregulated, while sulfur assimilation, sensing of ferric citrate and/or other iron carriers, heme acquisition, and transport of polar amino acids were downregulated. Our results provide directions to explore mechanisms of host adaptation in plant-associated microorganisms.
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Affiliation(s)
- Dorota M Krzyżanowska
- Laboratory of Plant Microbiology, Intercollegiate Faculty of Biotechnology UG and MUG, University of Gdańsk, ul. A. Abrahama 58, 80-307, Gdańsk, Poland
| | - Magdalena Jabłońska
- Laboratory of Plant Microbiology, Intercollegiate Faculty of Biotechnology UG and MUG, University of Gdańsk, ul. A. Abrahama 58, 80-307, Gdańsk, Poland
| | - Zbigniew Kaczyński
- Laboratory of Structural Biochemistry, Faculty of Chemistry, University of Gdańsk, ul. Wita Stwosza 63, 80-308, Gdańsk, Poland
| | - Małgorzata Czerwicka-Pach
- Laboratory of Structural Biochemistry, Faculty of Chemistry, University of Gdańsk, ul. Wita Stwosza 63, 80-308, Gdańsk, Poland
| | - Katarzyna Macur
- Laboratory of Mass Spectrometry, Intercollegiate Faculty of Biotechnology UG and MUG, University of Gdańsk, ul. A. Abrahama 58, 80-307, Gdańsk, Poland
| | - Sylwia Jafra
- Laboratory of Plant Microbiology, Intercollegiate Faculty of Biotechnology UG and MUG, University of Gdańsk, ul. A. Abrahama 58, 80-307, Gdańsk, Poland.
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Matarredona L, Camacho M, Bautista V, Bonete MJ, Esclapez J. Lrp as a potential transcriptional regulator involved in stress response in Haloferax mediterranei. Biochimie 2023; 209:61-72. [PMID: 36708868 DOI: 10.1016/j.biochi.2023.01.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 11/30/2022] [Accepted: 01/17/2023] [Indexed: 01/26/2023]
Abstract
The Archaea domain consists of a heterogeneous group of microorganisms with unique physiological properties that occupy a wide variety of niches in nature. Haloferax mediterranei is an extremely halophilic archaeon classified in the Phylum Euryarchaeota, which requires a high concentration of inorganic salts for optimal growth. In haloarchaea, transcription factors play a fundamental role in an adequate adaptation to environmental and nutritional changes, preserving the survival and integrity of the organism. To deepen knowledge of the Lrp/AsnC transcriptional regulator family, a lrp gene (HFX_RS01210) from this family has been studied. Site-directed mutagenesis has allowed us to identify the TATA-box and two potential sites of the transcriptional factor (TF) to its own promoter and autoregulate itself. Several approaches were carried out to elucidate whether this transcriptional regulator is involved in stresses due to heavy metals and limited nitrogen conditions. Characterization of the lrp deletion mutant and the Lrp overexpressed strain, suggests that the level of lrp expression depends on the nitrogen source and the presence of cobalt. The most striking results were obtained in the presence of nitrate as a nitrogen source due to the inability of the deletion mutant to grow. All these results confirm that Lrp is a powerful candidate for a regulatory role in the stress response, particularly under N-limiting conditions and the presence of cobalt.
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Affiliation(s)
- Laura Matarredona
- Biochemistry and Molecular Biology and Soil and Agricultural Chemistry Department, Biochemistry and Molecular Biology Area, Faculty of Science, University of Alicante, Ap 99, 03080, Alicante, Spain.
| | - Mónica Camacho
- Biochemistry and Molecular Biology and Soil and Agricultural Chemistry Department, Biochemistry and Molecular Biology Area, Faculty of Science, University of Alicante, Ap 99, 03080, Alicante, Spain.
| | - Vanesa Bautista
- Biochemistry and Molecular Biology and Soil and Agricultural Chemistry Department, Biochemistry and Molecular Biology Area, Faculty of Science, University of Alicante, Ap 99, 03080, Alicante, Spain.
| | - María-José Bonete
- Biochemistry and Molecular Biology and Soil and Agricultural Chemistry Department, Biochemistry and Molecular Biology Area, Faculty of Science, University of Alicante, Ap 99, 03080, Alicante, Spain.
| | - Julia Esclapez
- Biochemistry and Molecular Biology and Soil and Agricultural Chemistry Department, Biochemistry and Molecular Biology Area, Faculty of Science, University of Alicante, Ap 99, 03080, Alicante, Spain.
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Gao J, Du M, Zhao J, Yue zhang, Xu N, Du H, Ju J, Wei L, Liu J. Design of a genetically encoded biosensor to establish a high-throughput screening platform for L-cysteine overproduction. Metab Eng 2022; 73:144-157. [DOI: 10.1016/j.ymben.2022.07.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 07/03/2022] [Accepted: 07/21/2022] [Indexed: 11/30/2022]
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7
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Llorca MG, Martínez-Espinosa RM. Assessment of Haloferax mediterranei Genome in Search of Copper-Molecular Machinery With Potential Applications for Bioremediation. Front Microbiol 2022; 13:895296. [PMID: 35783429 PMCID: PMC9240420 DOI: 10.3389/fmicb.2022.895296] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Accepted: 05/27/2022] [Indexed: 11/13/2022] Open
Abstract
Heavy metals are essential micronutrients at low concentrations, serving as cofactors for relevant microbial enzymes (i.e., respiratory nitrate and nitrite reductases NADH dehydrogenase-2, amine oxidase, etc.), but they become harmful cellular intoxicants at significant low concentrations compared to other chemical compounds. The increasing need to incorporate bioremediation in the removal of heavy metals and other contaminants from wastewaters has led extremophiles to the spotlight of research. The haloarchaeon Haloferax mediterranei has promising physiological characteristics regarding bioremediation. However, little is known about how haloarchaea manage to resist high concentrations of heavy metals in the environment. The aim of this work is to develop bioinformatics research as the first step for further omics-based studies to shed light on copper metabolism in haloarchaea by analyzing H. mediterranei genome (strain ATCC 33500). To reach this aim, genome and protein databases have been consulted, and copper-related genes have been identified. BLAST analysis has been carried out to find similarities between copper resistance genes described from other microorganisms and H. mediterranei genes. Plausible copper importer genes, genes coding for siderophores, and copper exporters belonging to P1B-type ATPase group have been found apart from genes encoding copper chaperones, metal-responsive transcriptional regulators, and several proteins belonging to the cupredoxin superfamily: nitrite reductase, nitrous oxide reductases, cytochrome c oxidases, multicopper oxidases, and small blue copper proteins from the amicyanin/pseudoazurin families as halocyanins. As the presence of heavy metals causes oxidative stress, genes coding for proteins involved in antioxidant mechanisms have been also explored: thioredoxin, glutaredoxin, peroxiredoxin, catalase, and γ-glutamylcysteine as an analog of glutathione. Bioinformatic-based analysis of H. mediterranei genome has revealed a set of genes involved in copper metabolism that could be of interest for bioremediation purposes. The analysis of genes involved in antioxidative mechanisms against heavy metals makes it possible to infer the capability of H. mediterranei to synthesize inorganic polyphosphate granules against oxidative stress.
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Affiliation(s)
- Marina García Llorca
- Biochemistry and Molecular Biology Division, Department of Agrochemistry and Biochemistry, Faculty of Sciences, University of Alicante, Alicante, Spain
| | - Rosa María Martínez-Espinosa
- Biochemistry and Molecular Biology Division, Department of Agrochemistry and Biochemistry, Faculty of Sciences, University of Alicante, Alicante, Spain
- Multidisciplinary Institute for Environmental Studies “Ramón Margalef”, University of Alicante, Alicante, Spain
- *Correspondence: Rosa María Martínez-Espinosa,
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Liu R, Wei X, Song W, Wang L, Cao J, Wu J, Thomas T, Jin T, Wang Z, Wei W, Wei Y, Zhai H, Yao C, Shen Z, Du J, Fang J. Novel Chloroflexi genomes from the deepest ocean reveal metabolic strategies for the adaptation to deep-sea habitats. MICROBIOME 2022; 10:75. [PMID: 35538590 PMCID: PMC9088039 DOI: 10.1186/s40168-022-01263-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 03/24/2022] [Indexed: 05/04/2023]
Abstract
BACKGROUND The deep sea harbors the majority of the microbial biomass in the ocean and is a key site for organic matter (OM) remineralization and storage in the biosphere. Microbial metabolism in the deep ocean is greatly controlled by the generally depleted but periodically fluctuating supply of OM. Currently, little is known about metabolic potentials of dominant deep-sea microbes to cope with the variable OM inputs, especially for those living in the hadal trenches-the deepest part of the ocean. RESULTS In this study, we report the first extensive examination of the metabolic potentials of hadal sediment Chloroflexi, a dominant phylum in hadal trenches and the global deep ocean. In total, 62 metagenome-assembled-genomes (MAGs) were reconstructed from nine metagenomic datasets derived from sediments of the Mariana Trench. These MAGs represent six novel species, four novel genera, one novel family, and one novel order within the classes Anaerolineae and Dehalococcoidia. Fragment recruitment showed that these MAGs are globally distributed in deep-sea waters and surface sediments, and transcriptomic analysis indicated their in situ activities. Metabolic reconstruction showed that hadal Chloroflexi mainly had a heterotrophic lifestyle, with the potential to degrade a wide range of organic carbon, sulfur, and halogenated compounds. Our results revealed for the first time that hadal Chloroflexi harbor pathways for the complete hydrolytic or oxidative degradation of various recalcitrant OM, including aromatic compounds (e.g., benzoate), polyaromatic hydrocarbons (e.g., fluorene), polychlorobiphenyl (e.g., 4-chlorobiphenyl), and organochlorine compounds (e.g., chloroalkanes, chlorocyclohexane). Moreover, these organisms showed the potential to synthesize energy storage compounds (e.g., trehalose) and had regulatory modules to respond to changes in nutrient conditions. These metabolic traits suggest that Chloroflexi may follow a "feast-or-famine" metabolic strategy, i.e., preferentially consume labile OM and store the energy intracellularly under OM-rich conditions, and utilize the stored energy or degrade recalcitrant OM for survival under OM-limited condition. CONCLUSION This study expands the current knowledge on metabolic strategies in deep-ocean Chlorolfexi and highlights their significance in deep-sea carbon, sulfur, and halogen cycles. The metabolic plasticity likely provides Chloroflexi with advantages for survival under variable and heterogenic OM inputs in the deep ocean. Video Abstract.
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Affiliation(s)
- Rulong Liu
- Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai, China.
- National Engineering Research Center for Oceanic Fisheries, Shanghai Ocean University, Shanghai, China.
| | - Xing Wei
- Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai, China
- National Engineering Research Center for Oceanic Fisheries, Shanghai Ocean University, Shanghai, China
| | - Weizhi Song
- Centre for Marine Science & Innovation and School of Biological Earth and Environmental Science, University of New South Wales, Kensington, Australia
| | - Li Wang
- Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai, China
- National Engineering Research Center for Oceanic Fisheries, Shanghai Ocean University, Shanghai, China
| | - Junwei Cao
- Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai, China
- National Engineering Research Center for Oceanic Fisheries, Shanghai Ocean University, Shanghai, China
| | - Jiaxin Wu
- Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai, China
- National Engineering Research Center for Oceanic Fisheries, Shanghai Ocean University, Shanghai, China
| | - Torsten Thomas
- Centre for Marine Science & Innovation and School of Biological Earth and Environmental Science, University of New South Wales, Kensington, Australia
| | - Tao Jin
- BGI-Shenzhen, Shenzhen, Guangdong, China
| | - Zixuan Wang
- Tidal Flat Research Center of Jiangsu Province, Nanjing, Jiangsu, China
| | - Wenxia Wei
- Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai, China
- National Engineering Research Center for Oceanic Fisheries, Shanghai Ocean University, Shanghai, China
| | - Yuli Wei
- Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai, China
- National Engineering Research Center for Oceanic Fisheries, Shanghai Ocean University, Shanghai, China
| | - Haofeng Zhai
- Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai, China
- National Engineering Research Center for Oceanic Fisheries, Shanghai Ocean University, Shanghai, China
| | - Cheng Yao
- Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai, China
- National Engineering Research Center for Oceanic Fisheries, Shanghai Ocean University, Shanghai, China
| | - Ziyi Shen
- Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai, China
- National Engineering Research Center for Oceanic Fisheries, Shanghai Ocean University, Shanghai, China
| | - Jiangtao Du
- Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai, China
- National Engineering Research Center for Oceanic Fisheries, Shanghai Ocean University, Shanghai, China
| | - Jiasong Fang
- Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai, China.
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.
- Department of Natural Sciences, Hawaii Pacific University, Honolulu, HI, USA.
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Selvaraj C, Rudhra O, Alothaim AS, Alkhanani M, Singh SK. Structure and chemistry of enzymatic active sites that play a role in the switch and conformation mechanism. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2022; 130:59-83. [PMID: 35534116 DOI: 10.1016/bs.apcsb.2022.02.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Enzymes, which are biological molecules, are constructed from polypeptide chains, and these molecules are activated through reaction mechanisms. It is the role of enzymes to speed up chemical reactions that are used to build or break down cell structures. Activation energy is reduced by the enzymes' selective binding of substrates in a protected environment. In enzyme tertiary structures, the active sites are commonly situated in a "cleft," which necessitates the diffusion of substrates and products. The amino acid residues of the active site may be far apart in the primary structure owing to the folding required for tertiary structure. Due to their critical role in substrate binding and attraction, changes in amino acid structure at or near the enzyme's active site usually alter enzyme activity. At the enzyme's active site, or where the chemical reactions occur, the substrate is bound. Enzyme substrates are the primary targets of the enzyme's active site, which is designed to assist in the chemical reaction. This chapter elucidates the summary of structure and chemistry of enzymes, their active site features, charges and role of water in the structures to clarify the biochemistry of the enzymes in the depth of atomic features.
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Affiliation(s)
- Chandrabose Selvaraj
- Computer Aided Drug Design and Molecular Modelling Lab, Department of Bioinformatics, Science Block, Alagappa University, Karaikudi, Tamil Nadu, India.
| | - Ondipilliraja Rudhra
- Computer Aided Drug Design and Molecular Modelling Lab, Department of Bioinformatics, Science Block, Alagappa University, Karaikudi, Tamil Nadu, India
| | - Abdulaziz S Alothaim
- Department of Biology, College of Science in Zulfi, Majmaah University, Majmaah, Saudi Arabia
| | - Mustfa Alkhanani
- Emergency Service Department, College of Applied Sciences, Al Maarefa University, Riyadh, Saudi Arabia
| | - Sanjeev Kumar Singh
- Computer Aided Drug Design and Molecular Modelling Lab, Department of Bioinformatics, Science Block, Alagappa University, Karaikudi, Tamil Nadu, India.
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Hermann L, Dempwolff F, Steinchen W, Freibert SA, Smits SHJ, Seubert A, Bremer E. The MocR/GabR Ectoine and Hydroxyectoine Catabolism Regulator EnuR: Inducer and DNA Binding. Front Microbiol 2022; 12:764731. [PMID: 35003002 PMCID: PMC8739950 DOI: 10.3389/fmicb.2021.764731] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 12/01/2021] [Indexed: 11/26/2022] Open
Abstract
The compatible solutes ectoine and 5-hydroxyectoine are widely synthesized by bacteria as osmostress protectants. These nitrogen-rich tetrahydropyrimidines can also be exploited as nutrients by microorganisms. Many ectoine/5-hydroxyectoine catabolic gene clusters are associated with a regulatory gene (enuR: ectoine nutrient utilization regulator) encoding a repressor protein belonging to the MocR/GabR sub-family of GntR-type transcription factors. Focusing on EnuR from the marine bacterium Ruegeria pomeroyi, we show that the dimerization of EnuR is mediated by its aminotransferase domain. This domain can fold independently from its amino-terminal DNA reading head and can incorporate pyridoxal-5′-phosphate (PLP) as cofactor. The covalent attachment of PLP to residue Lys302 of EnuR was proven by mass-spectrometry. PLP interacts with system-specific, ectoine and 5-hydroxyectoine-derived inducers: alpha-acetyldiaminobutyric acid (alpha-ADABA), and hydroxy-alpha-acetyldiaminobutyric acid (hydroxy-alpha-ADABA), respectively. These inducers are generated in cells actively growing with ectoines as sole carbon and nitrogen sources, by the EutD hydrolase and targeted metabolic analysis allowed their detection. EnuR binds these effector molecules with affinities in the low micro-molar range. Studies addressing the evolutionary conservation of EnuR, modelling of the EnuR structure, and docking experiments with the inducers provide an initial view into the cofactor and effector binding cavity. In this cavity, the two high-affinity inducers for EnuR, alpha-ADABA and hydroxy-alpha-ADABA, are positioned such that their respective primary nitrogen group can chemically interact with PLP. Purified EnuR bound with micro-molar affinity to a 48 base pair DNA fragment containing the sigma-70 type substrate-inducible promoter for the ectoine/5-hydroxyectoine importer and catabolic gene cluster. Consistent with the function of EnuR as a repressor, the core elements of the promoter overlap with two predicted EnuR operators. Our data lend themselves to a straightforward regulatory model for the initial encounter of EnuR-possessing ectoine/5-hydroxyectoine consumers with environmental ectoines and for the situation when the external supply of these compounds has been exhausted by catabolism.
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Affiliation(s)
- Lucas Hermann
- Faculty of Biology, Philipps-University Marburg, Marburg, Germany.,Department of Biochemistry and Synthetic Metabolism, Max-Planck-Institute for Terrestrial Microbiology, Marburg, Germany
| | - Felix Dempwolff
- SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany
| | - Wieland Steinchen
- SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany
| | - Sven-Andreas Freibert
- Department of Medicine, Institute for Cytobiology and Cytopathology, and SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany
| | - Sander H J Smits
- Institute of Biochemistry, Heinrich-Heine-University, Düsseldorf, Germany.,Center for Structural Studies (CSS), Faculty of Biochemistry, Heinrich-Heine-University, Düsseldorf, Germany
| | - Andreas Seubert
- Faculty of Chemistry, Philipps-University Marburg, Marburg, Germany
| | - Erhard Bremer
- Faculty of Biology, Philipps-University Marburg, Marburg, Germany.,SYNMIKRO Research Center, Philipps-University Marburg, Marburg, Germany
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11
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Modrzejewska M, Kawalek A, Bartosik AA. The Lrp/AsnC-Type Regulator PA2577 Controls the EamA-like Transporter Gene PA2576 in Pseudomonas aeruginosa. Int J Mol Sci 2021; 22:13340. [PMID: 34948137 PMCID: PMC8707732 DOI: 10.3390/ijms222413340] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 12/04/2021] [Accepted: 12/10/2021] [Indexed: 11/16/2022] Open
Abstract
The regulatory network of gene expression in Pseudomonas aeruginosa, an opportunistic human pathogen, is very complex. In the PAO1 reference strain, about 10% of genes encode transcriptional regulators, many of which have undefined regulons and unknown functions. The aim of this study is the characterization of PA2577 protein, a representative of the Lrp/AsnC family of transcriptional regulators. This family encompasses proteins involved in the amino acid metabolism, regulation of transport processes or cell morphogenesis. The transcriptome profiling of P. aeruginosa cells with mild PA2577 overproduction revealed a decreased expression of the PA2576 gene oriented divergently to PA2577 and encoding an EamA-like transporter. A gene expression analysis showed a higher mRNA level of PA2576 in P. aeruginosa ΔPA2577, indicating that PA2577 acts as a repressor. Concomitantly, ChIP-seq and EMSA assays confirmed strong interactions of PA2577 with the PA2577/PA2576 intergenic region. Additionally, phenotype microarray analyses indicated an impaired metabolism of ΔPA2576 and ΔPA2577 mutants in the presence of polymyxin B, which suggests disturbances of membrane functions in these mutants. We show that PA2576 interacts with two proteins, PA5006 and PA3694, with a predicted role in lipopolysaccharide (LPS) and membrane biogenesis. Overall, our results indicate that PA2577 acts as a repressor of the PA2576 gene coding for the EamA-like transporter and may play a role in the modulation of the cellular response to stress conditions, including antimicrobial peptides, e.g., polymyxin B.
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Affiliation(s)
| | | | - Aneta Agnieszka Bartosik
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland; (M.M.); (A.K.)
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12
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Mirzaei R, Dehkhodaie E, Bouzari B, Rahimi M, Gholestani A, Hosseini-Fard SR, Keyvani H, Teimoori A, Karampoor S. Dual role of microbiota-derived short-chain fatty acids on host and pathogen. Biomed Pharmacother 2021; 145:112352. [PMID: 34840032 DOI: 10.1016/j.biopha.2021.112352] [Citation(s) in RCA: 62] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Revised: 10/15/2021] [Accepted: 10/19/2021] [Indexed: 12/12/2022] Open
Abstract
A growing body of documents shows microbiota produce metabolites such as short-chain fatty acids (SCFAs) as crucial executors of diet-based microbial influence the host and bacterial pathogens. The production of SCFAs depends on the metabolic activity of intestinal microflora and is also affected by dietary changes. SCFAs play important roles in maintaining colonic health as an energy source, as a regulator of gene expression and cell differentiation, and as an anti-inflammatory agent. Additionally, the regulated expression of virulence genes is critical for successful infection by an intestinal pathogen. Bacteria rely on sensing environmental signals to find preferable niches and reach the infectious state. This review will present data supporting the diverse functional roles of microbiota-derived butyrate, propionate, and acetate on host cellular activities such as immune modulation, energy metabolism, nervous system, inflammation, cellular differentiation, and anti-tumor effects, among others. On the other hand, we will discuss and summarize data about the role of these SCFAs on the virulence factor of bacterial pathogens. In this regard, receptors and signaling routes for SCFAs metabolites in host and pathogens will be introduced.
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Affiliation(s)
- Rasoul Mirzaei
- Department of Microbiology, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran; Venom and Biotherapeutics Molecules Lab, Medical Biotechnology Department, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran.
| | - Elahe Dehkhodaie
- Department of Biology, Science and Research Branch, Islamic Azad University Tehran, Iran
| | - Behnaz Bouzari
- Department of Pathology, Firouzgar Hospital, Iran University of Medical Sciences, Tehran, Iran
| | - Mandana Rahimi
- Department of Pathology, School of Medicine, Hasheminejad Kidney Center, Iran University of Medical Sciences, Tehran, Iran
| | - Abolfazl Gholestani
- Department of Biochemistry, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Seyed Reza Hosseini-Fard
- Department of Biochemistry, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Hossein Keyvani
- Gastrointestinal and Liver Diseases Research Center, Iran University of Medical Sciences, Tehran, Iran; Department of Virology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran.
| | - Ali Teimoori
- Department of Virology, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran.
| | - Sajad Karampoor
- Gastrointestinal and Liver Diseases Research Center, Iran University of Medical Sciences, Tehran, Iran; Department of Virology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran.
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13
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Intelligent host engineering for metabolic flux optimisation in biotechnology. Biochem J 2021; 478:3685-3721. [PMID: 34673920 PMCID: PMC8589332 DOI: 10.1042/bcj20210535] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2021] [Revised: 09/22/2021] [Accepted: 09/24/2021] [Indexed: 12/13/2022]
Abstract
Optimising the function of a protein of length N amino acids by directed evolution involves navigating a 'search space' of possible sequences of some 20N. Optimising the expression levels of P proteins that materially affect host performance, each of which might also take 20 (logarithmically spaced) values, implies a similar search space of 20P. In this combinatorial sense, then, the problems of directed protein evolution and of host engineering are broadly equivalent. In practice, however, they have different means for avoiding the inevitable difficulties of implementation. The spare capacity exhibited in metabolic networks implies that host engineering may admit substantial increases in flux to targets of interest. Thus, we rehearse the relevant issues for those wishing to understand and exploit those modern genome-wide host engineering tools and thinking that have been designed and developed to optimise fluxes towards desirable products in biotechnological processes, with a focus on microbial systems. The aim throughput is 'making such biology predictable'. Strategies have been aimed at both transcription and translation, especially for regulatory processes that can affect multiple targets. However, because there is a limit on how much protein a cell can produce, increasing kcat in selected targets may be a better strategy than increasing protein expression levels for optimal host engineering.
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14
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Leucine-Responsive Regulatory Protein in Acetic Acid Bacteria Is Stable and Functions at a Wide Range of Intracellular pH Levels. J Bacteriol 2021; 203:e0016221. [PMID: 34228496 DOI: 10.1128/jb.00162-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Acetic acid bacteria grow while producing acetic acid, resulting in acidification of the culture. Limited reports elucidate the effect of changes in intracellular pH on transcriptional factors. In the present study, the intracellular pH of Komagataeibacter europaeus was monitored with a pH-sensitive green fluorescent protein, showing that the intracellular pH decreased from 6.3 to 4.7 accompanied by acetic acid production during cell growth. The leucine-responsive regulatory protein of K. europaeus (KeLrp) was used as a model to examine pH-dependent effects, and its properties were compared with those of the Escherichia coli ortholog (EcLrp) at different pH levels. The DNA-binding activities of EcLrp and KeLrp with the target DNA (Ec-ilvI and Ke-ilvI) were examined by gel mobility shift assays under various pH conditions. EcLrp showed the highest affinity with the target at pH 8.0 (Kd [dissociation constant], 0.7 μM), decreasing to a minimum of 3.4 μM at pH 4.0. Conversely, KeLrp did not show significant differences in binding affinity between pH 4 and 7 (Kd, 1.0 to 1.5 μM), and the highest affinity was at pH 5.0 (Kd, 1.0 μM). Circular dichroism spectroscopy revealed that the α-helical content of KeLrp was the highest at pH 5.0 (49%) and was almost unchanged while being maintained at >45% over a range of pH levels examined, while that of EcLrp decreased from its maximum (49% at pH 7.0) to its minimum (36% at pH 4.0). These data indicate that KeLrp is stable and functions over a wide range of intracellular pH levels. IMPORTANCE Lrp is a highly conserved transcriptional regulator found in bacteria and archaea and regulates transcriptions of various genes. The intracellular pH of acetic acid bacteria (AAB) changes accompanied by acetic acid production during cell growth. The Lrp of AAB K. europaeus (KeLrp) was structurally stable over a wide range of pH and maintained DNA-binding activity even at low pH compared with Lrp from E. coli living in a neutral environment. An in vitro experiment showed DNA-binding activity of KeLrp to the target varied with changes in pH. In AAB, change of the intracellular pH during a cell growth would be an important trigger in controlling the activity of Lrp in vivo.
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15
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Activation of the type VI secretion system in the squid symbiont Vibrio fischeri requires the transcriptional regulator TasR and the structural proteins TssM and TssA. J Bacteriol 2021; 203:e0039921. [PMID: 34370559 PMCID: PMC8508121 DOI: 10.1128/jb.00399-21] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacteria have evolved diverse strategies to compete for a niche, including the type VI secretion system (T6SS), a contact-dependent killing mechanism. T6SSs are common in bacterial pathogens, commensals, and beneficial symbionts, where they affect the diversity and spatial structure of host-associated microbial communities. Although T6SS gene clusters are often located on genomic islands (GIs), which may be transferred as a unit, the regulatory strategies that promote gene expression once the T6SS genes are transferred into a new cell are not known. We used the squid symbiont, Vibrio fischeri, to identify essential regulatory factors that control expression of a strain-specific T6SS encoded on a GI. We found that a transcriptional reporter for this T6SS is active only in strains that contain the T6SS-encoding GI, suggesting the GI encodes at least one essential regulator. A transposon screen identified seven mutants that could not activate the reporter. These mutations mapped exclusively to three genes on the T6SS-containing GI that encode two essential structural proteins (a TssA-like protein and TssM) and a transcriptional regulator (TasR). Using T6SS reporters, RT-PCR, competition assays, and differential proteomics, we found that all three genes are required for expression of many T6SS components, except for the TssA-like protein and TssM, which are constitutively expressed. Based on these findings, we propose a model whereby T6SS expression requires conserved structural proteins, in addition to the essential regulator TasR, and this ability to self-regulate may be a strategy to activate T6SS expression upon transfer of T6SS-encoding elements into a new bacterial host. Importance Interbacterial weapons like the T6SS are often located on mobile genetic elements and their expression is highly regulated. We found that two conserved structural proteins are required for T6SS expression in Vibrio fischeri. These structural proteins also contain predicted GTPase and GTP binding domains, suggesting their role in promoting T6SS expression may involve sensing the energetic state of the cell. Such a mechanism would provide a direct link between T6SS activation and cellular energy levels, providing a "checkpoint" to ensure the cell has sufficient energy to build such a costly weapon. Because these regulatory factors are encoded within the T6SS gene cluster, they are predicted to move with the genetic element to activate T6SS expression in a new host cell.
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16
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Hermann L, Mais CN, Czech L, Smits SHJ, Bange G, Bremer E. The ups and downs of ectoine: structural enzymology of a major microbial stress protectant and versatile nutrient. Biol Chem 2021; 401:1443-1468. [PMID: 32755967 DOI: 10.1515/hsz-2020-0223] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 07/22/2020] [Indexed: 12/13/2022]
Abstract
Ectoine and its derivative 5-hydroxyectoine are compatible solutes and chemical chaperones widely synthesized by Bacteria and some Archaea as cytoprotectants during osmotic stress and high- or low-growth temperature extremes. The function-preserving attributes of ectoines led to numerous biotechnological and biomedical applications and fostered the development of an industrial scale production process. Synthesis of ectoines requires the expenditure of considerable energetic and biosynthetic resources. Hence, microorganisms have developed ways to exploit ectoines as nutrients when they are no longer needed as stress protectants. Here, we summarize our current knowledge on the phylogenomic distribution of ectoine producing and consuming microorganisms. We emphasize the structural enzymology of the pathways underlying ectoine biosynthesis and consumption, an understanding that has been achieved only recently. The synthesis and degradation pathways critically differ in the isomeric form of the key metabolite N-acetyldiaminobutyric acid (ADABA). γ-ADABA serves as preferred substrate for the ectoine synthase, while the α-ADABA isomer is produced by the ectoine hydrolase as an intermediate in catabolism. It can serve as internal inducer for the genetic control of ectoine catabolic genes via the GabR/MocR-type regulator EnuR. Our review highlights the importance of structural enzymology to inspire the mechanistic understanding of metabolic networks at the biological scale.
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Affiliation(s)
- Lucas Hermann
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von Frisch Str. 8, D-35043 Marburg, Germany.,Biochemistry and Synthetic Biology of Microbial Metabolism Group, Max Planck Institute for Terrestrial Microbiology, Karl-von Frisch Str. 10, D-35043 Marburg, Germany
| | - Christopher-Nils Mais
- Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Chemistry, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
| | - Laura Czech
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von Frisch Str. 8, D-35043 Marburg, Germany.,Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Chemistry, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
| | - Sander H J Smits
- Center for Structural Studies, Heinrich Heine University Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf, Germany.,Institute of Biochemistry, Heinrich Heine University Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf, Germany
| | - Gert Bange
- Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Chemistry, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
| | - Erhard Bremer
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von Frisch Str. 8, D-35043 Marburg, Germany.,Center for Synthetic Microbiology (SYNMIKRO), Philipps University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
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17
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Solano-Collado V, Ruiz-Cruz S, Lorenzo-Díaz F, Pluta R, Espinosa M, Bravo A. Recognition of Streptococcal Promoters by the Pneumococcal SigA Protein. Front Mol Biosci 2021; 8:666504. [PMID: 34250014 PMCID: PMC8264293 DOI: 10.3389/fmolb.2021.666504] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 06/14/2021] [Indexed: 11/13/2022] Open
Abstract
Promoter recognition by RNA polymerase is a key step in the regulation of gene expression. The bacterial RNA polymerase core enzyme is a complex of five subunits that interacts transitory with one of a set of sigma factors forming the RNA polymerase holoenzyme. The sigma factor confers promoter specificity to the RNA polymerase. In the Gram-positive pathogenic bacterium Streptococcus pneumoniae, most promoters are likely recognized by SigA, a poorly studied housekeeping sigma factor. Here we present a sequence conservation analysis and show that SigA has similar protein architecture to Escherichia coli and Bacillus subtilis homologs, namely the poorly conserved N-terminal 100 residues and well-conserved rest of the protein (domains 2, 3, and 4). Further, we have purified the native (untagged) SigA protein encoded by the pneumococcal R6 strain and reconstituted an RNA polymerase holoenzyme composed of the E. coli core enzyme and the sigma factor SigA (RNAP-SigA). By in vitro transcription, we have found that RNAP-SigA was able to recognize particular promoters, not only from the pneumococcal chromosome but also from the S. agalactiae promiscuous antibiotic-resistance plasmid pMV158. Specifically, SigA was able to direct the RNA polymerase to transcribe genes involved in replication and conjugative mobilization of plasmid pMV158. Our results point to the versatility of SigA in promoter recognition and its contribution to the promiscuity of plasmid pMV158.
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Affiliation(s)
| | - Sofía Ruiz-Cruz
- School of Microbiology, University College Cork, Cork, Ireland
| | - Fabián Lorenzo-Díaz
- Departamento de Bioquímica, Microbiología, Biología Celular y Genética, Universidad de La Laguna, Tenerife, Spain
| | - Radoslaw Pluta
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Manuel Espinosa
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Alicia Bravo
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
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18
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Ziegler CA, Freddolino PL. The leucine-responsive regulatory proteins/feast-famine regulatory proteins: an ancient and complex class of transcriptional regulators in bacteria and archaea. Crit Rev Biochem Mol Biol 2021; 56:373-400. [PMID: 34151666 DOI: 10.1080/10409238.2021.1925215] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Since the discovery of the Escherichia coli leucine-responsive regulatory protein (Lrp) almost 50 years ago, hundreds of Lrp homologs have been discovered, occurring in 45% of sequenced bacteria and almost all sequenced archaea. Lrp-like proteins are often referred to as the feast/famine regulatory proteins (FFRPs), reflecting their common regulatory roles. Acting as either global or local transcriptional regulators, FFRPs detect the environmental nutritional status by sensing small effector molecules (usually amino acids) and regulate the expression of genes involved in metabolism, virulence, motility, nutrient transport, stress tolerance, and antibiotic resistance to implement appropriate behaviors for the specific ecological niche of each organism. Despite FFRPs' complexity, a significant role in gene regulation, and prevalence throughout prokaryotes, the last comprehensive review on this family of proteins was published about a decade ago. In this review, we integrate recent notable findings regarding E. coli Lrp and other FFRPs across bacteria and archaea with previous observations to synthesize a more complete view on the mechanistic details and biological roles of this ancient class of transcription factors.
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Affiliation(s)
- Christine A Ziegler
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Peter L Freddolino
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, USA.,Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI, USA
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19
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Mariadasse R, Rajmichael R, Dwivedy A, Amala M, Ahmad M, Mutharasappan N, Biswal BK, Jeyakanthan J. Characterization of putative transcriptional regulator (PH0140) and its distal homologue. Cell Signal 2021; 84:110031. [PMID: 33932498 DOI: 10.1016/j.cellsig.2021.110031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 04/13/2021] [Accepted: 04/26/2021] [Indexed: 11/28/2022]
Abstract
In this study, a phylogenetic tree was constructed using 1854 sequences of various Lrp/AnsC (FFRPs) and ArsR proteins from pathogenic and non-pathogenic organisms. Despite having sequence similarities, FFRPs and ArsR proteins functioning differently as a transcriptional regulator and de-repressor in the presence of exogenous amino acids and metal ions, respectively. To understand these functional differences, the structures of various FFRPs and ArsR proteins (134 sequences) were modeled. Several ArsR proteins exhibited high similarity to the FFRPs while in few proteins, unusual structural folds were observed. However, the Helix-turn-Helix (HTH) domains are common among them and the ligand-binding domains are structurally dissimilar suggest the differences in their binding preferences. Despite low sequence conservation, most of these proteins revealed negatively charged surfaces in the active site pockets. Representative structures (PH0140 and TtArsR protein) from FFRPs and ArsR protein families were considered and evaluated for their functional differences using molecular modeling studies. Our earlier study has explained the binding preference of exogenous Tryptophan and the related transcriptional regulatory mechanism of PH0140 protein. In this study, a Cu2+ ion-induced de-repression mechanism of the TtArsR-DNA complex was characterized through docking and molecular dynamics. Further, the proteins were purified and their efficiency for sensing Tryptophan and Cu2+ ions were analyzed using cyclic voltammetry. Overall, the study explores the structural evolution and functional difference of FFRPs and ArsR proteins that present the possibilities of PH0140 and TtArsR as potential bio-sensory molecules.
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Affiliation(s)
- Richard Mariadasse
- Structural Biology and Bio-Computing Lab, Department of Bioinformatics, Science Block, Alagappa University, Karaikudi 630 004, India
| | - Raji Rajmichael
- Structural Biology and Bio-Computing Lab, Department of Bioinformatics, Science Block, Alagappa University, Karaikudi 630 004, India
| | | | - Mathimaran Amala
- Structural Biology and Bio-Computing Lab, Department of Bioinformatics, Science Block, Alagappa University, Karaikudi 630 004, India
| | | | - Nachiappan Mutharasappan
- Structural Biology and Bio-Computing Lab, Department of Bioinformatics, Science Block, Alagappa University, Karaikudi 630 004, India
| | | | - Jeyaraman Jeyakanthan
- Structural Biology and Bio-Computing Lab, Department of Bioinformatics, Science Block, Alagappa University, Karaikudi 630 004, India.
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20
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Pastor-Soler S, Camacho M, Bautista V, Bonete MJ, Esclapez J. Towards the Elucidation of Assimilative nasABC Operon Transcriptional Regulation in Haloferax mediterranei. Genes (Basel) 2021; 12:genes12050619. [PMID: 33921943 PMCID: PMC8143581 DOI: 10.3390/genes12050619] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Revised: 04/14/2021] [Accepted: 04/20/2021] [Indexed: 11/22/2022] Open
Abstract
The assimilatory pathway of the nitrogen cycle in the haloarchaeon Haloferax mediterranei has been well described and characterized in previous studies. However, the regulatory mechanisms involved in the gene expression of this pathway remain unknown in haloarchaea. This work focuses on elucidating the regulation at the transcriptional level of the assimilative nasABC operon (HFX_2002 to HFX_2004) through different approaches. Characterization of its promoter region using β-galactosidase as a reporter gene and site-directed mutagenesis has allowed us to identify possible candidate binding regions for a transcriptional factor. The identification of a potential transcriptional regulator related to nitrogen metabolism has become a real challenge due to the lack of information on haloarchaea. The investigation of protein–DNA binding by streptavidin bead pull-down analysis combined with mass spectrometry resulted in the in vitro identification of a transcriptional regulator belonging to the Lrp/AsnC family, which binds to the nasABC operon promoter (p.nasABC). To our knowledge, this study is the first report to suggest the AsnC transcriptional regulator as a powerful candidate to play a regulatory role in nasABC gene expression in Hfx. mediterranei and, in general, in the assimilatory nitrogen pathway.
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21
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Rauf A, Khalil AA, Rahman UU, Khalid A, Naz S, Shariati MA, Rebezov M, Urtecho EZ, de Albuquerque RDDG, Anwar S, Alamri A, Saini RK, Rengasamy KRR. Recent advances in the therapeutic application of short-chain fatty acids (SCFAs): An updated review. Crit Rev Food Sci Nutr 2021; 62:6034-6054. [PMID: 33703960 DOI: 10.1080/10408398.2021.1895064] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Over the past decade, the gut microbiota has emerged as an important frontier in understanding the human body's homeostasis and the development of diseases. Gut flora in human beings regulates various metabolic functionalities, including enzymes, amino acid synthesis, bio-transformation of bile acid, fermentation of non-digestible carbohydrates (NDCs), generation of indoles and polyamines (PAs), and production of short-chain fatty acids (SCFAs). Among all the metabolites produced by gut microbiota, SCFAs, the final product of fermentation of dietary fibers by gut microbiota, receive lots of attention from scientists due to their pharmacological and physiological characteristics. However, the molecular mechanisms underlying the role of SCFAs in the interaction between diet, gut microbiota, and host energy metabolism is still needed in-depth research. This review highlights the recent biotechnological advances in applying SCFAs as important metabolites to treat various diseases and maintain colonic health.
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Affiliation(s)
- Abdur Rauf
- Department of Chemistry, University of Swabi, Swabi, Anbar, Khyber Pakhtunkhwa (KP), Pakistan
| | - Anees Ahmed Khalil
- University Institute of Diet and Nutritional Sciences, Faculty of Allied Health Sciences, The University of Lahore, Pakistan
| | - Ubaid-Ur- Rahman
- School of Food and Agricultural Sciences, University of Management and Technology, Lahore, Pakistan
| | - Ahood Khalid
- University Institute of Diet and Nutritional Sciences, Faculty of Allied Health Sciences, The University of Lahore, Pakistan
| | - Saima Naz
- Deaprtment of Biotechnology, Woman University Mardan, Mardan, Khyber Pakhtunkhwa (KP), Pakistan
| | - Mohammad Ali Shariati
- K.G. Razumovsky, Moscow State University of Technologies and Management (the First Cossack University), Moscow, Russian
| | - Maksim Rebezov
- V.M. Gorbatov Federal Research Center for Food Systems of Russian Academy of Sciences, Moscow, Russian.,Prokhorov General Physics Institute of the, Russian Academy of Science, Moscow, Russian
| | | | | | - Sirajudheen Anwar
- Department of Pharmacology & Toxicology, College of Pharmacy, University of Hail, Hail, KSA
| | - Abdulwahab Alamri
- Department of Pharmacology & Toxicology, College of Pharmacy, University of Hail, Hail, KSA
| | | | - Kannan R R Rengasamy
- Indigenous Knowledge Systems Centre, Faculty of Natural and Agricultural Sciences, North-West University, Mmabatho, North West Province, South Africa
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22
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Cao M, Goodrich-Blair H. Xenorhabdus nematophila bacteria shift from mutualistic to virulent Lrp-dependent phenotypes within the receptacles of Steinernema carpocapsae insect-infective stage nematodes. Environ Microbiol 2020; 22:5433-5449. [PMID: 33078552 DOI: 10.1111/1462-2920.15286] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 10/03/2020] [Accepted: 10/18/2020] [Indexed: 01/06/2023]
Abstract
Xenorhabdus nematophila bacteria are mutualists of Steinernema carpocapsae nematodes and pathogens of insects. Xenorhabdus nematophila exhibits phenotypic variation between insect virulence (V) and the mutualistic (M) support of nematode reproduction and colonization initiation in the infective juvenile (IJ) stage nematode that carries X. nematophila between insect hosts. The V and M phenotypes occur reciprocally depending on levels of the transcription factor Lrp: high-Lrp expressors are M+V- while low-Lrp expressors are V+M-. We report here that variable (wild type) or fixed high-Lrp expressors also are optimized, relative to low- or no-Lrp expressors, for colonization of additional nematode stages: juvenile, adult and pre-transmission infective juvenile (IJ). In contrast, we found that after the bacterial population had undergone outgrowth in mature IJs, the advantage for colonization shifted to low-Lrp expressors: fixed low-Lrp expressors (M-V+) and wild type (M+V+) exhibited higher average bacterial CFU per IJ than did high-Lrp (M+V-) or no-Lrp (M-V-) strains. Further, the bacterial population becomes increasingly low-Lrp expressing, based on expression of an Lrp-dependent fluorescent reporter, as IJs age. These data support a model that virulent X. nematophila have a selective advantage and accumulate in aging IJs in advance of exposure to insect hosts in which this phenotype is necessary.
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Affiliation(s)
- Mengyi Cao
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Heidi Goodrich-Blair
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, 53706, USA.,Department of Microbiology, University of Tennessee, Knoxville, TN, 37996, USA
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Sivakumar R, Gunasekaran P, Rajendhran J. Functional characterization of asnC family transcriptional regulator in Pseudomonas aeruginosa PGPR2 during root colonization. Mol Biol Rep 2020; 47:7941-7957. [PMID: 33011891 DOI: 10.1007/s11033-020-05872-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 09/28/2020] [Indexed: 12/18/2022]
Abstract
Transcriptional regulators in bacteria are the crucial players in mediating communication between environmental cues and DNA transcription through a complex network process. Pseudomonas aeruginosa PGPR2 is an efficient root colonizer and a biocontrol strain. Previously, we identified that the transcriptional regulator, asnC, negatively regulates the corn root colonization of P. aeruginosa PGPR2. In a transposon insertion sequencing (INSeq) screen, the asnC insertion mutant was positively selected during root colonization, meaning the disruption of asnC improves the fitness of the P. aeruginosa PGPR2 strain for the root colonization. In this study, we constructed isogenic mutant of asnC family transcriptional regulator encoded by PGPR2_17510 by allele exchange mutagenesis. The ΔasnC mutant was able to efficiently colonize corn roots with a twofold increase in population when compared to the wild-type strain. Similarly, the mutant strain outcompeted the wild-type strain in a competition assay, where the mutant strain represented 90% of the total population recovered from the root. We compared the whole transcriptome of the wild-type and the ΔasnC mutant of P. aeruginosa PGPR2 when exposed to the corn root exudates. The RNA-Seq revealed that a total of 360 genes were differentially expressed in the ΔasnC strain of P. aeruginosa PGPR2. Inactivation of asnC transcriptional regulator resulted in the up-regulation of several genetic factors implicated in metabolism, uptake of nutrients, motility, stress response, and signal transduction, which could play crucial roles in root colonization. This notion was further validated by phenotypic characterization and quantification of transcription pattern of selected genes associated with metabolism, motility, and carbon catabolite repression between wild type and mutant strain, which was in agreement with transcriptome data. Similarly, ΔasnC strain formed increased biofilm on abiotic surface validating our RNA-seq analysis, where transcript levels of several genes associated with biofilm formation were up-regulated in the mutant strain. We report that the inactivation of an asnC family transcriptional regulator encoded by PGPR2_17510 enhances the root colonization and biofilm-forming ability of P. aeruginosa PGPR2. Together, our results provide evidence for the molecular adaptations that enable ΔasnC mutant strain to colonize on the corn roots and to form a biofilm.
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Affiliation(s)
- Ramamoorthy Sivakumar
- Department of Genetics, School of Biological Sciences, Madurai Kamaraj University, Madurai, 625 021, India
| | | | - Jeyaprakash Rajendhran
- Department of Genetics, School of Biological Sciences, Madurai Kamaraj University, Madurai, 625 021, India.
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Bylino OV, Ibragimov AN, Shidlovskii YV. Evolution of Regulated Transcription. Cells 2020; 9:E1675. [PMID: 32664620 PMCID: PMC7408454 DOI: 10.3390/cells9071675] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 07/07/2020] [Accepted: 07/10/2020] [Indexed: 12/12/2022] Open
Abstract
The genomes of all organisms abound with various cis-regulatory elements, which control gene activity. Transcriptional enhancers are a key group of such elements in eukaryotes and are DNA regions that form physical contacts with gene promoters and precisely orchestrate gene expression programs. Here, we follow gradual evolution of this regulatory system and discuss its features in different organisms. In eubacteria, an enhancer-like element is often a single regulatory element, is usually proximal to the core promoter, and is occupied by one or a few activators. Activation of gene expression in archaea is accompanied by the recruitment of an activator to several enhancer-like sites in the upstream promoter region. In eukaryotes, activation of expression is accompanied by the recruitment of activators to multiple enhancers, which may be distant from the core promoter, and the activators act through coactivators. The role of the general DNA architecture in transcription control increases in evolution. As a whole, it can be seen that enhancers of multicellular eukaryotes evolved from the corresponding prototypic enhancer-like regulatory elements with the gradually increasing genome size of organisms.
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Affiliation(s)
- Oleg V. Bylino
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., 119334 Moscow, Russia; (O.V.B.); (A.N.I.)
| | - Airat N. Ibragimov
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., 119334 Moscow, Russia; (O.V.B.); (A.N.I.)
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., 119334 Moscow, Russia
| | - Yulii V. Shidlovskii
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., 119334 Moscow, Russia; (O.V.B.); (A.N.I.)
- I.M. Sechenov First Moscow State Medical University, 8, bldg. 2 Trubetskaya St., 119048 Moscow, Russia
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Prathiviraj R, Chellapandi P. Modeling a global regulatory network of Methanothermobacter thermautotrophicus strain ∆H. ACTA ACUST UNITED AC 2020. [DOI: 10.1007/s13721-020-0223-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Comparative genomics analysis of Nitriliruptoria reveals the genomic differences and salt adaptation strategies. Extremophiles 2019; 24:249-264. [PMID: 31820112 DOI: 10.1007/s00792-019-01150-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Accepted: 11/25/2019] [Indexed: 12/22/2022]
Abstract
The group Nitriliruptoria, recently classified as a separate class of phylum Actinobacteria, has five members at present, which belong to halophilic or halotolerant Actinobacteria. Here, we sequenced the genomes of Egicoccus halophilus EGI 80432T and Egibacter rhizosphaerae EGI 80759T, and performed a comparative genomics approach to analyze the genomic differences and salt adaptation mechanisms in Nitriliruptoria. Phylogenetic analysis suggested that Euzebya tangerina F10T has a closer phylogenetic relationship to Euzebya rosea DSW09T, while genomic analysis revealed highest genomic similarity with Nitriliruptor alkaliphilus ANL-iso2T and E. halophilus EGI 80432T. Genomic differences of Nitriliruptoria were mainly observed in genome size, gene contents, and the amounts of gene in per functional categories. Furthermore, our analysis also revealed that Nitriliruptoria possess similar synthesis systems of solutes, such as trehalose, glutamine, glutamate, and proline. On the other hand, each member of Nitriliruptoria species possesses specific mechanisms, K+ influx and efflux, betaine and ectoine synthesis, and compatible solutes transport to survive in various high-salt environments.
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Mariadasse R, Choubey SK, Jeyakanthan J. Insights into Exogenous Tryptophan-Mediated Allosteric Communication and Helical Transition of TRP Protein for Transcription Regulation. J Chem Inf Model 2019; 60:175-191. [DOI: 10.1021/acs.jcim.9b00755] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Richard Mariadasse
- Structural Biology and Bio-Computing Lab, Department of Bioinformatics, Science Block, Alagappa University, Karaikudi, 630 004 Tamil Nadu, India
| | - Sanjay Kumar Choubey
- Structural Biology and Bio-Computing Lab, Department of Bioinformatics, Science Block, Alagappa University, Karaikudi, 630 004 Tamil Nadu, India
| | - Jeyaraman Jeyakanthan
- Structural Biology and Bio-Computing Lab, Department of Bioinformatics, Science Block, Alagappa University, Karaikudi, 630 004 Tamil Nadu, India
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28
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Transcription Regulators in Archaea: Homologies and Differences with Bacterial Regulators. J Mol Biol 2019; 431:4132-4146. [DOI: 10.1016/j.jmb.2019.05.045] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 05/08/2019] [Accepted: 05/24/2019] [Indexed: 11/17/2022]
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Bischof LF, Haurat MF, Albers SV. Two membrane-bound transcription factors regulate expression of various type-IV-pili surface structures in Sulfolobus acidocaldarius. PeerJ 2019; 7:e6459. [PMID: 30828487 PMCID: PMC6396743 DOI: 10.7717/peerj.6459] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 01/15/2019] [Indexed: 11/20/2022] Open
Abstract
In Archaea and Bacteria, gene expression is tightly regulated in response to environmental stimuli. In the thermoacidophilic crenarchaeon Sulfolobus acidocaldarius nutrient limitation induces expression of the archaellum, the archaeal motility structure. This expression is orchestrated by a complex hierarchical network of positive and negative regulators-the archaellum regulatory network (arn). The membrane-bound one-component system ArnR and its paralog ArnR1 were recently described as main activators of archaellum expression in S. acidocaldarius. They regulate gene expression of the archaellum operon by targeting the promoter of flaB, encoding the archaellum filament protein. Here we describe a strategy for the isolation and biochemical characterization of these two archaellum regulators. Both regulators are capable of forming oligomers and are phosphorylated by the Ser/Thr kinase ArnC. Apart from binding to pflaB, ArnR but not ArnR1 bound to promoter sequences of aapF and upsX, which encode components of the archaeal adhesive pilus and UV-inducible pili system, demonstrating a regulatory connection between different surface appendages of S. acidocaldarius.
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Affiliation(s)
- Lisa Franziska Bischof
- Institute of Biology II, Molecular Biology of Archaea, University of Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine (SGBM), Freiburg, Germany
| | - Maria Florencia Haurat
- Department of Molecular Microbiology, Washington University, School of Medicine in St. Louis, St. Louis, MO, USA
| | - Sonja-Verena Albers
- Institute of Biology II, Molecular Biology of Archaea, University of Freiburg, Freiburg, Germany
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Wu B, Qin H, Yang Y, Duan G, Yang S, Xin F, Zhao C, Shao H, Wang Y, Zhu Q, Tan F, Hu G, He M. Engineered Zymomonas mobilis tolerant to acetic acid and low pH via multiplex atmospheric and room temperature plasma mutagenesis. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:10. [PMID: 30627218 PMCID: PMC6321654 DOI: 10.1186/s13068-018-1348-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 12/24/2018] [Indexed: 05/19/2023]
Abstract
BACKGROUND Cellulosic biofuels are sustainable compared to fossil fuels. However, inhibitors, such as acetic acid generated during lignocellulose pretreatment and hydrolysis, would significantly inhibit microbial fermentation efficiency. Microbial mutants able to tolerate high concentration of acetic acid are needed urgently to alleviate this inhibition. RESULTS Zymomonas mobilis mutants AQ8-1 and AC8-9 with enhanced tolerance against acetic acid were generated via a multiplex atmospheric and room temperature plasma (mARTP) mutagenesis. The growth and ethanol productivity of AQ8-1 and AC8-9 were both improved in the presence of 5.0-8.0 g/L acetic acid. Ethanol yield reached 84% of theoretical value in the presence of 8.0 g/L acetic acid (~ pH 4.0). Furthermore, a mutant tolerant to pH 3.5, named PH1-29, was generated via the third round of ARTP mutagenesis. PH1-29 showed enhanced growth and ethanol production under both sterilized/unsterilized conditions at pH 4.0 or 3.5. Intracellular NAD levels revealed that mARTP mutants could modulate NADH/NAD+ ratio to respond to acetic acid and low pH stresses. Moreover, genomic re-sequencing revealed that eleven single nucleic variations (SNVs) were likely related to acetic acid and low pH tolerance. Most SNVs were targeted in regions between genes ZMO0952 and ZMO0956, ZMO0152 and ZMO0153, and ZMO0373 and ZMO0374. CONCLUSIONS The multiplex mutagenesis strategy mARTP was efficient for enhancing the tolerance in Z. mobilis. The ARTP mutants generated in this study could serve as potential cellulosic ethanol producers.
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Affiliation(s)
- Bo Wu
- Biomass Energy Technology Research Centre, Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Rd. South, Chengdu, 610041 China
| | - Han Qin
- Biomass Energy Technology Research Centre, Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Rd. South, Chengdu, 610041 China
| | - Yiwei Yang
- Biomass Energy Technology Research Centre, Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Rd. South, Chengdu, 610041 China
| | - Guowei Duan
- Biomass Energy Technology Research Centre, Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Rd. South, Chengdu, 610041 China
| | - Shihui Yang
- Hubei Collaborative Innovation Center for Green Transformation of Bio-resources, Environmental Microbial Technology Center of Hubei Province, Hubei Key Laboratory of Industrial Biotechnology, College of Life Sciences, Hubei University, Wuhan, 430062 China
| | - Fengxue Xin
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30 Puzhu Rd, Pukou District, Nanjing, 211816 China
| | - Chunyan Zhao
- College of Life Science, Sichuan Normal University, Section 2-1819, Chenglong Avenue, Chengdu, 610101 China
| | - Huanhuan Shao
- College of Life Science, Sichuan Normal University, Section 2-1819, Chenglong Avenue, Chengdu, 610101 China
| | - Yanwei Wang
- Biomass Energy Technology Research Centre, Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Rd. South, Chengdu, 610041 China
| | - Qili Zhu
- Biomass Energy Technology Research Centre, Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Rd. South, Chengdu, 610041 China
| | - Furong Tan
- Biomass Energy Technology Research Centre, Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Rd. South, Chengdu, 610041 China
| | - Guoquan Hu
- Biomass Energy Technology Research Centre, Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Rd. South, Chengdu, 610041 China
| | - Mingxiong He
- Biomass Energy Technology Research Centre, Key Laboratory of Development and Application of Rural Renewable Energy (Ministry of Agriculture), Biogas Institute of Ministry of Agriculture, Section 4-13, Renmin Rd. South, Chengdu, 610041 China
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31
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Redox, amino acid, and fatty acid metabolism intersect with bacterial virulence in the gut. Proc Natl Acad Sci U S A 2018; 115:E10712-E10719. [PMID: 30348782 DOI: 10.1073/pnas.1813451115] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The gut metabolic landscape is complex and is influenced by the microbiota, host physiology, and enteric pathogens. Pathogens have to exquisitely monitor the biogeography of the gastrointestinal tract to find a suitable niche for colonization. To dissect the important metabolic pathways that influence virulence of enterohemorrhagic Escherichia coli (EHEC), we conducted a high-throughput screen. We generated a dataset of regulatory pathways that control EHEC virulence expression under anaerobic conditions. This unraveled that the cysteine-responsive regulator, CutR, converges with the YhaO serine import pump and the fatty acid metabolism regulator FadR to optimally control virulence expression in EHEC. CutR activates expression of YhaO to increase activity of the YhaJ transcription factor that has been previously shown to directly activate the EHEC virulence genes. CutR enhances FadL, which is a pump for fatty acids that represses inhibition of virulence expression by FadR, unmasking a feedback mechanism responsive to metabolite fluctuations. Moreover, CutR and FadR also augment murine infection by Citrobacter rodentium, which is a murine pathogen extensively employed as a surrogate animal model for EHEC. This high-throughput approach proved to be a powerful tool to map the web of cellular circuits that allows an enteric pathogen to monitor the gut environment and adjust the levels of expression of its virulence repertoire toward successful infection of the host.
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VqsA, a Novel LysR-Type Transcriptional Regulator, Coordinates Quorum Sensing (QS) and Is Controlled by QS To Regulate Virulence in the Pathogen Vibrio alginolyticus. Appl Environ Microbiol 2018; 84:AEM.00444-18. [PMID: 29625990 DOI: 10.1128/aem.00444-18] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 03/30/2018] [Indexed: 12/12/2022] Open
Abstract
The quorum sensing (QS) system controls bacterial group behaviors in response to cell density. In vibrios, LuxR and AphA are two master QS regulators (MQSRs) controlling gene expression in response to high or low cell density. Other regulators involved in the regulation of these two MQSRs and QS pathways remain to be determined. Here, we performed bacterial one-hybrid (B1H)-assay-based screens of transcriptional factors (TFs) to identify TFs that can directly regulate the expression of luxR and aphA from a library of 285 TFs encoded by the fish pathogen Vibrio alginolyticus A total of 7 TFs were identified to bind to the promoters of both luxR and aphA Among these TFs, the novel LysR-type transcriptional regulator (LTTR) VqsA could activate LuxR and repress AphA transcription. Meanwhile, LuxR and AphA exerted feedback inhibition and activation of vqsA expression, respectively, indicating that VqsA coordinates QS and is also regulated by QS. In addition, VqsA inhibited its own expression by directly binding to its own promoter region. The VqsA-binding sites in the promoter regions of luxR and aphA as well as the binding sites of LuxR, AphA, and VqsA in the vqsA gene were uncovered by electrophoretic mobility shift assays (EMSAs) and DNase I footprinting analysis. Finally, VqsA was verified to play essential roles in QS-regulated phenotypes, i.e., type VI secretion system 2 (T6SS2)-dependent interbacterial competition, biofilm formation, exotoxin production, and in vivo virulence of V. alginolyticus Collectively, our data showed that VqsA is an important QS regulator in V. alginolyticusIMPORTANCE Investigation of the mechanism of regulation of quorum sensing (QS) systems will facilitate an understanding of bacterial pathogenesis and the identification of effective QS interference (QSI) targets. Here, we systematically screened transcriptional factors (TFs) that modulate the expression of the master QS regulators (MQSRs) LuxR and AphA, and a novel LysR-type transcriptional regulator, VqsA, was identified. Our data illuminated the mechanisms mediating the interaction among LuxR, AphA, and VqsA as well as the effects of these regulators on the expression and output of QS. The impaired expression of virulence genes as a result of vqsA disruption demonstrated that VqsA is an important player in QS regulation and pathogenesis and may be the third MQSR involved in sensing environmental signals by vibrios to coordinate QS responses. This study will facilitate the development of strategies to interfere with QS and effectively control this pathogen that plagues the aquaculture industry.
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Czech L, Hermann L, Stöveken N, Richter AA, Höppner A, Smits SHJ, Heider J, Bremer E. Role of the Extremolytes Ectoine and Hydroxyectoine as Stress Protectants and Nutrients: Genetics, Phylogenomics, Biochemistry, and Structural Analysis. Genes (Basel) 2018; 9:genes9040177. [PMID: 29565833 PMCID: PMC5924519 DOI: 10.3390/genes9040177] [Citation(s) in RCA: 119] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Revised: 03/13/2018] [Accepted: 03/15/2018] [Indexed: 01/26/2023] Open
Abstract
Fluctuations in environmental osmolarity are ubiquitous stress factors in many natural habitats of microorganisms, as they inevitably trigger osmotically instigated fluxes of water across the semi-permeable cytoplasmic membrane. Under hyperosmotic conditions, many microorganisms fend off the detrimental effects of water efflux and the ensuing dehydration of the cytoplasm and drop in turgor through the accumulation of a restricted class of organic osmolytes, the compatible solutes. Ectoine and its derivative 5-hydroxyectoine are prominent members of these compounds and are synthesized widely by members of the Bacteria and a few Archaea and Eukarya in response to high salinity/osmolarity and/or growth temperature extremes. Ectoines have excellent function-preserving properties, attributes that have led to their description as chemical chaperones and fostered the development of an industrial-scale biotechnological production process for their exploitation in biotechnology, skin care, and medicine. We review, here, the current knowledge on the biochemistry of the ectoine/hydroxyectoine biosynthetic enzymes and the available crystal structures of some of them, explore the genetics of the underlying biosynthetic genes and their transcriptional regulation, and present an extensive phylogenomic analysis of the ectoine/hydroxyectoine biosynthetic genes. In addition, we address the biochemistry, phylogenomics, and genetic regulation for the alternative use of ectoines as nutrients.
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Affiliation(s)
- Laura Czech
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
| | - Lucas Hermann
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
| | - Nadine Stöveken
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
- LOEWE-Center for Synthetic Microbiology, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany.
| | - Alexandra A Richter
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
| | - Astrid Höppner
- Center for Structural Studies, Heinrich-Heine University Düsseldorf, Universitäts Str. 1, D-40225 Düsseldorf, Germany.
| | - Sander H J Smits
- Center for Structural Studies, Heinrich-Heine University Düsseldorf, Universitäts Str. 1, D-40225 Düsseldorf, Germany.
- Institute of Biochemistry, Heinrich-Heine University Düsseldorf, Universitäts Str. 1, D-40225 Düsseldorf, Germany.
| | - Johann Heider
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
- LOEWE-Center for Synthetic Microbiology, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany.
| | - Erhard Bremer
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
- LOEWE-Center for Synthetic Microbiology, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany.
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Ishii Y, Akasaka N, Sakoda H, Hidese R, Fujiwara S. Leucine responsive regulatory protein is involved in methionine metabolism and polyamine homeostasis in acetic acid bacterium Komagataeibacter europaeus. J Biosci Bioeng 2018; 125:67-75. [DOI: 10.1016/j.jbiosc.2017.07.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 07/03/2017] [Accepted: 07/31/2017] [Indexed: 01/29/2023]
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35
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Schulz A, Hermann L, Freibert SA, Bönig T, Hoffmann T, Riclea R, Dickschat JS, Heider J, Bremer E. Transcriptional regulation of ectoine catabolism in response to multiple metabolic and environmental cues. Environ Microbiol 2017; 19:4599-4619. [PMID: 28892254 DOI: 10.1111/1462-2920.13924] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2017] [Revised: 08/29/2017] [Accepted: 08/31/2017] [Indexed: 01/04/2023]
Abstract
Ectoine and hydroxyectoine are effective microbial osmostress protectants, but can also serve as versatile nutrients for bacteria. We have studied the genetic regulation of ectoine and hydroxyectoine import and catabolism in the marine Roseobacter species Ruegeria pomeroyi and identified three transcriptional regulators involved in these processes: the GabR/MocR-type repressor EnuR, the feast and famine-type regulator AsnC and the two-component system NtrYX. The corresponding genes are widely associated with ectoine and hydroxyectoine uptake and catabolic gene clusters (enuR, asnC), and with microorganisms predicted to consume ectoines (ntrYX). EnuR contains a covalently bound pyridoxal-5'-phosphate as a co-factor and the chemistry underlying the functioning of MocR/GabR-type regulators typically requires a system-specific low molecular mass effector molecule. Through ligand binding studies with purified EnuR, we identified N-(alpha)-L-acetyl-2,4-diaminobutyric acid and L-2,4-diaminobutyric acid as inducers for EnuR that are generated through ectoine catabolism. AsnC/Lrp-type proteins can wrap DNA into nucleosome-like structures, and we found that the asnC gene was essential for use of ectoines as nutrients. Furthermore, we discovered through transposon mutagenesis that the NtrYX two-component system is required for their catabolism. Database searches suggest that our findings have important ramifications for an understanding of the molecular biology of most microbial consumers of ectoines.
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Affiliation(s)
- Annina Schulz
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany
| | - Lucas Hermann
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany
| | - Sven-Andreas Freibert
- Department of Medicine, Institute for Cytobiology and Cytopathology, Philipps-University Marburg, Robert-Koch Str. 6, D-35032 Marburg, Germany
| | - Tobias Bönig
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany
| | - Tamara Hoffmann
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany
| | - Ramona Riclea
- Institute of Organic Chemistry, Technical University Braunschweig, D-38106 Braunschweig, Germany.,Kekulé-Institute for Organic Chemistry and Biochemistry, Friedrich-Wilhelms-Universität Bonn, D-53121 Bonn, Germany
| | - Jeroen S Dickschat
- Institute of Organic Chemistry, Technical University Braunschweig, D-38106 Braunschweig, Germany.,Kekulé-Institute for Organic Chemistry and Biochemistry, Friedrich-Wilhelms-Universität Bonn, D-53121 Bonn, Germany
| | - Johann Heider
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany.,LOEWE-Center for Synthetic Microbiology, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
| | - Erhard Bremer
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von-Frisch-Str. 8, D-35043 Marburg, Germany.,LOEWE-Center for Synthetic Microbiology, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
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Cao M, Goodrich-Blair H. Ready or Not: Microbial Adaptive Responses in Dynamic Symbiosis Environments. J Bacteriol 2017; 199:e00883-16. [PMID: 28484049 PMCID: PMC5512229 DOI: 10.1128/jb.00883-16] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In mutually beneficial and pathogenic symbiotic associations, microbes must adapt to the host environment for optimal fitness. Both within an individual host and during transmission between hosts, microbes are exposed to temporal and spatial variation in environmental conditions. The phenomenon of phenotypic variation, in which different subpopulations of cells express distinctive and potentially adaptive characteristics, can contribute to microbial adaptation to a lifestyle that includes rapidly changing environments. The environments experienced by a symbiotic microbe during its life history can be erratic or predictable, and each can impact the evolution of adaptive responses. In particular, the predictability of a rhythmic or cyclical series of environments may promote the evolution of signal transduction cascades that allow preadaptive responses to environments that are likely to be encountered in the future, a phenomenon known as adaptive prediction. In this review, we summarize environmental variations known to occur in some well-studied models of symbiosis and how these may contribute to the evolution of microbial population heterogeneity and anticipatory behavior. We provide details about the symbiosis between Xenorhabdus bacteria and Steinernema nematodes as a model to investigate the concept of environmental adaptation and adaptive prediction in a microbial symbiosis.
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Affiliation(s)
- Mengyi Cao
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Heidi Goodrich-Blair
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Department of Microbiology, University of Tennessee Knoxville, Knoxville, Tennessee, USA
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High Levels of the Xenorhabdus nematophila Transcription Factor Lrp Promote Mutualism with the Steinernema carpocapsae Nematode Host. Appl Environ Microbiol 2017; 83:AEM.00276-17. [PMID: 28389546 DOI: 10.1128/aem.00276-17] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 04/04/2017] [Indexed: 11/20/2022] Open
Abstract
Xenorhabdus nematophila bacteria are mutualistic symbionts of Steinernema carpocapsae nematodes and pathogens of insects. The X. nematophila global regulator Lrp controls the expression of many genes involved in both mutualism and pathogenic activities, suggesting a role in the transition between the two host organisms. We previously reported that natural populations of X. nematophila exhibit various levels of Lrp expression and that cells expressing relatively low levels of Lrp are optimized for virulence in the insect Manduca sexta The adaptive advantage of the high-Lrp-expressing state was not established. Here we used strains engineered to express constitutively high or low levels of Lrp to test the model in which high-Lrp-expressing cells are adapted for mutualistic activities with the nematode host. We demonstrate that high-Lrp cells form more robust biofilms in laboratory media than do low-Lrp cells, which may reflect adherence to host tissues. Also, our data showed that nematodes cultivated with high-Lrp strains are more frequently colonized than are those associated with low-Lrp strains. Taken together, these data support the idea that high-Lrp cells have an advantage in tissue adherence and colonization initiation. Furthermore, our data show that high-Lrp-expressing strains better support nematode reproduction than do their low-Lrp counterparts under both in vitro and in vivo conditions. Our data indicate that heterogeneity of Lrp expression in X. nematophila populations provides diverse cell populations adapted to both pathogenic (low-Lrp) and mutualistic (high-Lrp) states.IMPORTANCE Host-associated bacteria experience fluctuating conditions during both residence within an individual host and transmission between hosts. For bacteria that engage in evolutionarily stable, long-term relationships with particular hosts, these fluctuations provide selective pressure for the emergence of adaptive regulatory mechanisms. Here we present evidence that the bacterium Xenorhabdus nematophila uses various levels of the transcription factor Lrp to optimize its association with its two animal hosts, nematodes and insects, with which it behaves as a mutualist and a pathogen, respectively. Building on our previous finding that relatively low cellular levels of Lrp are optimal for pathogenesis, we demonstrate that, conversely, high levels of Lrp promote mutualistic activities with the Steinernema carpocapsae nematode host. These data suggest that X. nematophila has evolved to utilize phenotypic variation between high- and low-Lrp-expression states to optimize its alternating behaviors as a mutualist and a pathogen.
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Neisseria meningitidis Uses Sibling Small Regulatory RNAs To Switch from Cataplerotic to Anaplerotic Metabolism. mBio 2017; 8:mBio.02293-16. [PMID: 28325760 PMCID: PMC5362039 DOI: 10.1128/mbio.02293-16] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Neisseria meningitidis (the meningococcus) is primarily a commensal of the human oropharynx that sporadically causes septicemia and meningitis. Meningococci adapt to diverse local host conditions differing in nutrient supply, like the nasopharynx, blood, and cerebrospinal fluid, by changing metabolism and protein repertoire. However, regulatory transcription factors and two-component systems in meningococci involved in adaptation to local nutrient variations are limited. We identified novel sibling small regulatory RNAs ( Neisseriametabolic switch regulators [NmsRs]) regulating switches between cataplerotic and anaplerotic metabolism in this pathogen. Overexpression of NmsRs was tolerated in blood but not in cerebrospinal fluid. Expression of six tricarboxylic acid cycle enzymes was downregulated by direct action of NmsRs. Expression of the NmsRs themselves was under the control of the stringent response through the action of RelA. Small sibling regulatory RNAs of meningococci, controlling general metabolic switches, add an exciting twist to their versatile repertoire in bacterial pathogens.IMPORTANCE Regulatory small RNAs (sRNAs) of pathogens are coming to be recognized as highly important components of riboregulatory networks, involved in the control of essential cellular processes. They play a prominent role in adaptation to physiological changes as represented by different host environments. They can function as posttranscriptional regulators of gene expression to orchestrate metabolic adaptation to nutrient stresses. Here, we identified highly conserved sibling sRNAs in Neisseria meningitidis which are functionally involved in the regulation of gene expression of components of the tricarboxylic acid cycle. These novel sibling sRNAs that function by antisense mechanisms extend the so-called stringent response which connects metabolic status to colonization and possibly virulence as well as pathogenesis in meningococci.
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Transcription Factor-Mediated Gene Regulation in Archaea. RNA METABOLISM AND GENE EXPRESSION IN ARCHAEA 2017. [DOI: 10.1007/978-3-319-65795-0_2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
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Liu H, Wang K, Lindås AC, Peeters E. The genome-scale DNA-binding profile of BarR, a β-alanine responsive transcription factor in the archaeon Sulfolobus acidocaldarius. BMC Genomics 2016; 17:569. [PMID: 27502941 PMCID: PMC4977709 DOI: 10.1186/s12864-016-2890-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2016] [Accepted: 07/06/2016] [Indexed: 01/09/2023] Open
Abstract
Background The Leucine-responsive Regulatory Protein (Lrp) family is a widespread family of regulatory transcription factors in prokaryotes. BarR is an Lrp-like transcription factor in the model archaeon Sulfolobus acidocaldarius that activates the expression of a β-alanine aminotransferase gene, which is involved in β-alanine degradation. In contrast to classical Lrp-like transcription factors, BarR is not responsive to any of the α-amino acids but interacts specifically with β-alanine. Besides the juxtaposed β-alanine aminotransferase gene, other regulatory targets of BarR have not yet been identified although β-alanine is the precursor of coenzyme A and thus an important central metabolite. The aim of this study is to extend the knowledge of the DNA-binding characteristics of BarR and of its corresponding regulon from a local to a genome-wide perspective. Results We characterized the genome-wide binding profile of BarR using chromatin immunoprecipation combined with high-throughput sequencing (ChIP-seq). This revealed 21 genomic binding loci. High-enrichment binding regions were validated to interact with purified BarR protein in vitro using electrophoretic mobility shift assays and almost all targets were also shown to harbour a conserved semi-palindromic binding motif. Only a small subset of enriched genomic sites are located in intergenic regions at a relative short distance to a promoter, and qRT-PCR analysis demonstrated that only one additional operon is under activation of BarR, namely the glutamine synthase operon. The latter is also a target of other Lrp-like transcription factors. Detailed inspection of the BarR ChIP-seq profile at the β-alanine aminotransferase promoter region in combination with binding motif predictions indicate that the operator structure is more complicated than previously anticipated, consisting of multiple (major and auxiliary) operators. Conclusions BarR has a limited regulon, and includes also glutamine synthase genes besides the previously characterized β-alanine aminotransferase. Regulation of glutamine synthase is suggestive of a link between β-alanine and α-amino acid metabolism in S. acidocaldarius. Furthermore, this work reveals that the BarR regulon overlaps with that of other Lrp-like regulators. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2890-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Han Liu
- Department of Bio-Engineering Sciences, Research Group of Microbiology, Vrije Universiteit Brussel, Pleinlaan 2, B-1050, Brussels, Belgium
| | - Kun Wang
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrhenius v. 20C, SE-10691, Stockholm, Sweden
| | - Ann-Christin Lindås
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrhenius v. 20C, SE-10691, Stockholm, Sweden
| | - Eveline Peeters
- Department of Bio-Engineering Sciences, Research Group of Microbiology, Vrije Universiteit Brussel, Pleinlaan 2, B-1050, Brussels, Belgium.
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Unoarumhi Y, Blumenthal RM, Matson JS. Evolution of a global regulator: Lrp in four orders of γ-Proteobacteria. BMC Evol Biol 2016; 16:111. [PMID: 27206730 PMCID: PMC4875751 DOI: 10.1186/s12862-016-0685-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 05/12/2016] [Indexed: 11/11/2022] Open
Abstract
Background Bacterial global regulators each regulate the expression of several hundred genes. In Escherichia coli, the top seven global regulators together control over half of all genes. Leucine-responsive regulatory protein (Lrp) is one of these top seven global regulators. Lrp orthologs are very widely distributed, among both Bacteria and Archaea. Surprisingly, even within the phylum γ-Proteobacteria (which includes E. coli), Lrp is a global regulator in some orders and a local regulator in others. This raises questions about the evolution of Lrp and, more broadly, of global regulators. Results We examined Lrp sequences from four bacterial orders of the γ-Proteobacteria using phylogenetic and Logo analyses. The orders studied were Enterobacteriales and Vibrionales, in which Lrp plays a global role in tested species; Pasteurellales, in which Lrp is a local regulator in the tested species; and Alteromonadales, an order closely related to the other three but in which Lrp has not yet been studied. For comparison, we analyzed the Lrp paralog AsnC, which in all tested cases is a local regulator. The Lrp and AsnC phylogenetic clusters each divided, as expected, into subclusters representing the Enterobacteriales, Vibrionales, and Pasteuralles. However the Alteromonadales did not yield coherent clusters for either Lrp or AsnC. Logo analysis revealed signatures associated with globally- vs. locally- acting Lrp orthologs, providing testable hypotheses for which portions of Lrp are responsible for a global vs. local role. These candidate regions include both ends of the Lrp polypeptide but not, interestingly, the highly-conserved helix-turn-helix motif responsible for DNA sequence specificity. Conclusions Lrp and AsnC have conserved sequence signatures that allow their unambiguous annotation, at least in γ-Proteobacteria. Among Lrp orthologs, specific residues correlated with global vs. local regulatory roles, and can now be tested to determine which are functionally relevant and which simply reflect divergence. In the Alteromonadales, it appears that there are different subgroups of Lrp orthologs, one of which may act globally while the other may act locally. These results suggest experiments to improve our understanding of the evolution of bacterial global regulators. Electronic supplementary material The online version of this article (doi:10.1186/s12862-016-0685-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yvette Unoarumhi
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA.,Program in Bioinformatics and Proteomics/Genomics, University of Toledo College of Medicine and Life Sciences, Toledo, OH, USA
| | - Robert M Blumenthal
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA.,Program in Bioinformatics and Proteomics/Genomics, University of Toledo College of Medicine and Life Sciences, Toledo, OH, USA
| | - Jyl S Matson
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, Ohio, USA.
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Torrey HL, Keren I, Via LE, Lee JS, Lewis K. High Persister Mutants in Mycobacterium tuberculosis. PLoS One 2016; 11:e0155127. [PMID: 27176494 PMCID: PMC4866775 DOI: 10.1371/journal.pone.0155127] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Accepted: 04/25/2016] [Indexed: 11/18/2022] Open
Abstract
Mycobacterium tuberculosis forms drug-tolerant persister cells that are the probable cause of its recalcitrance to antibiotic therapy. While genetically identical to the rest of the population, persisters are dormant, which protects them from killing by bactericidal antibiotics. The mechanism of persister formation in M. tuberculosis is not well understood. In this study, we selected for high persister (hip) mutants and characterized them by whole genome sequencing and transcriptome analysis. In parallel, we identified and characterized clinical isolates that naturally produce high levels of persisters. We compared the hip mutants obtained in vitro with clinical isolates to identify candidate persister genes. Genes involved in lipid biosynthesis, carbon metabolism, toxin-antitoxin systems, and transcriptional regulators were among those identified. We also found that clinical hip isolates exhibited greater ex vivo survival than the low persister isolates. Our data suggest that M. tuberculosis persister formation involves multiple pathways, and hip mutants may contribute to the recalcitrance of the infection.
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Affiliation(s)
- Heather L. Torrey
- Department of Biology, Northeastern University, Boston, Massachusetts, United States of America
| | - Iris Keren
- Department of Biology, Northeastern University, Boston, Massachusetts, United States of America
| | - Laura E. Via
- Tuberculosis Research Section, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Jong Seok Lee
- International Tuberculosis Research Center, Changwon, Republic of Korea
| | - Kim Lewis
- Department of Biology, Northeastern University, Boston, Massachusetts, United States of America
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Bacterial Cysteine-Inducible Cysteine Resistance Systems. J Bacteriol 2016; 198:1384-92. [PMID: 26883827 DOI: 10.1128/jb.01039-15] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2015] [Accepted: 02/12/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Cysteine donates sulfur to macromolecules and occurs naturally in many proteins. Because low concentrations of cysteine are cytotoxic, its intracellular concentration is stringently controlled. In bacteria, cysteine biosynthesis is regulated by feedback inhibition of the activities of serine acetyltransferase (SAT) and 3-phosphoglycerate dehydrogenase (3-PGDH) and is also regulated at the transcriptional level by inducing the cysteine regulon using the master regulator CysB. Here, we describe two novel cysteine-inducible systems that regulate the cysteine resistance of Pantoea ananatis, a member of the family Enterobacteriaceae that shows great potential for producing substances useful for biotechnological, medical, and industrial purposes. One locus, designated ccdA(formerly PAJ_0331), encodes a novel cysteine-inducible cysteine desulfhydrase (CD) that degrades cysteine, and its expression is controlled by the transcriptional regulator encoded byccdR(formerly PAJ_0332 orybaO), located just upstream of ccdA The other locus, designated cefA (formerly PAJ_3026), encodes a novel cysteine-inducible cysteine efflux pump that is controlled by the transcriptional regulator cefR(formerly PAJ_3027), located just upstream of cefA To our knowledge, this is the first example where the expression of CD and an efflux pump is regulated in response to cysteine and is directly involved in imparting resistance to excess levels of cysteine. We propose that ccdA and cefA function as safety valves that maintain homeostasis when the intra- or extracellular cysteine concentration fluctuates. Our findings contribute important insights into optimizing the production of cysteine and related biomaterials by P. ananatis IMPORTANCE Because of its toxicity, the bacterial intracellular cysteine level is stringently regulated at biosynthesis. This work describes the identification and characterization of two novel cysteine-inducible systems that regulate, through degradation and efflux, the cysteine resistance of Pantoea ananatis, a member of the family Enterobacteriaceae that shows great potential for producing substances useful for industrial purposes. We propose that this novel mechanism for sensing and regulating cysteine levels is a safety valve enabling adaptation to sudden changes in intra- or extracellular cysteine levels in bacteria. Our findings provide important insights into optimizing the production of cysteine and related biomaterials by P. ananatis and also a deep understanding of sulfur/cysteine metabolism and regulation in this plant pathogen and related bacteria.
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Song N, Cui Y, Li Z, Chen L, Liu S. New Targets and Cofactors for the Transcription Factor LrpA fromMycobacterium tuberculosis. DNA Cell Biol 2016; 35:167-76. [DOI: 10.1089/dna.2015.3040] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Affiliation(s)
- Ningning Song
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Yingying Cui
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
- College of Animal Science and Technology, Jilin Agricultural University, Changchun, China
| | - Zhaoli Li
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Liping Chen
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Siguo Liu
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
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Dey A, Shree S, Pandey SK, Tripathi RP, Ramachandran R. Crystal Structure of Mycobacterium tuberculosis H37Rv AldR (Rv2779c), a Regulator of the ald Gene: DNA BINDING AND IDENTIFICATION OF SMALL MOLECULE INHIBITORS. J Biol Chem 2016; 291:11967-80. [PMID: 27006398 DOI: 10.1074/jbc.m115.700484] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Indexed: 11/06/2022] Open
Abstract
Here we report the crystal structure of M. tuberculosis AldR (Rv2779c) showing that the N-terminal DNA-binding domains are swapped, forming a dimer, and four dimers are assembled into an octamer through crystal symmetry. The C-terminal domain is involved in oligomeric interactions that stabilize the oligomer, and it contains the effector-binding sites. The latter sites are 30-60% larger compared with homologs like MtbFFRP (Rv3291c) and can consequently accommodate larger molecules. MtbAldR binds to the region upstream to the ald gene that is highly up-regulated in nutrient-starved tuberculosis models and codes for l-alanine dehydrogenase (MtbAld; Rv2780). Further, the MtbAldR-DNA complex is inhibited upon binding of Ala, Tyr, Trp and Asp to the protein. Studies involving a ligand-binding site G131T mutant show that the mutant forms a DNA complex that cannot be inhibited by adding the amino acids. Comparative studies suggest that binding of the amino acids changes the relative spatial disposition of the DNA-binding domains and thereby disrupt the protein-DNA complex. Finally, we identified small molecules, including a tetrahydroquinoline carbonitrile derivative (S010-0261), that inhibit the MtbAldR-DNA complex. The latter molecules represent the very first inhibitors of a feast/famine regulatory protein from any source and set the stage for exploring MtbAldR as a potential anti-tuberculosis target.
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Affiliation(s)
- Abhishek Dey
- From the Molecular and Structural Biology Division and
| | - Sonal Shree
- From the Molecular and Structural Biology Division and
| | - Sarvesh Kumar Pandey
- the Medicinal and Process Chemistry Division, Council of Scientific and Industrial Research-Central Drug Research Institute, Jankipuram Extension, Sitapur Road, Lucknow, Uttar Pradesh 226031, India
| | - Rama Pati Tripathi
- the Medicinal and Process Chemistry Division, Council of Scientific and Industrial Research-Central Drug Research Institute, Jankipuram Extension, Sitapur Road, Lucknow, Uttar Pradesh 226031, India
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Romero-Rodríguez A, Robledo-Casados I, Sánchez S. An overview on transcriptional regulators in Streptomyces. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2015; 1849:1017-39. [PMID: 26093238 DOI: 10.1016/j.bbagrm.2015.06.007] [Citation(s) in RCA: 107] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Revised: 06/09/2015] [Accepted: 06/12/2015] [Indexed: 12/19/2022]
Abstract
Streptomyces are Gram-positive microorganisms able to adapt and respond to different environmental conditions. It is the largest genus of Actinobacteria comprising over 900 species. During their lifetime, these microorganisms are able to differentiate, produce aerial mycelia and secondary metabolites. All of these processes are controlled by subtle and precise regulatory systems. Regulation at the transcriptional initiation level is probably the most common for metabolic adaptation in bacteria. In this mechanism, the major players are proteins named transcription factors (TFs), capable of binding DNA in order to repress or activate the transcription of specific genes. Some of the TFs exert their action just like activators or repressors, whereas others can function in both manners, depending on the target promoter. Generally, TFs achieve their effects by using one- or two-component systems, linking a specific type of environmental stimulus to a transcriptional response. After DNA sequencing, many streptomycetes have been found to have chromosomes ranging between 6 and 12Mb in size, with high GC content (around 70%). They encode for approximately 7000 to 10,000 genes, 50 to 100 pseudogenes and a large set (around 12% of the total chromosome) of regulatory genes, organized in networks, controlling gene expression in these bacteria. Among the sequenced streptomycetes reported up to now, the number of transcription factors ranges from 471 to 1101. Among these, 315 to 691 correspond to transcriptional regulators and 31 to 76 are sigma factors. The aim of this work is to give a state of the art overview on transcription factors in the genus Streptomyces.
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Affiliation(s)
- Alba Romero-Rodríguez
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México, D.F. 04510, Mexico
| | - Ivonne Robledo-Casados
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México, D.F. 04510, Mexico
| | - Sergio Sánchez
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México, D.F. 04510, Mexico.
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Lewis DL, Notey JS, Chandrayan SK, Loder AJ, Lipscomb GL, Adams MWW, Kelly RM. A mutant ('lab strain') of the hyperthermophilic archaeon Pyrococcus furiosus, lacking flagella, has unusual growth physiology. Extremophiles 2014; 19:269-81. [PMID: 25472011 DOI: 10.1007/s00792-014-0712-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Accepted: 11/16/2014] [Indexed: 10/24/2022]
Abstract
A mutant ('lab strain') of the hyperthermophilic archaeon Pyrococcus furiosus DSM3638 exhibited an extended exponential phase and atypical cell aggregation behavior. Genomic DNA from the mutant culture was sequenced and compared to wild-type (WT) DSM3638, revealing 145 genes with one or more insertions, deletions, or substitutions (12 silent, 33 amino acid substitutions, and 100 frame shifts). Approximately, half of the mutated genes were transposases or hypothetical proteins. The WT transcriptome revealed numerous changes in amino acid and pyrimidine biosynthesis pathways coincidental with growth phase transitions, unlike the mutant whose transcriptome reflected the observed prolonged exponential phase. Targeted gene deletions, based on frame-shifted ORFs in the mutant genome, in a genetically tractable strain of P. furiosus (COM1) could not generate the extended exponential phase behavior observed for the mutant. For example, a putative radical SAM family protein (PF2064) was the most highly up-regulated ORF (>25-fold) in the WT between exponential and stationary phase, although this ORF was unresponsive in the mutant; deletion of this gene in P. furiosus COM1 resulted in no apparent phenotype. On the other hand, frame-shifting mutations in the mutant genome negatively impacted transcription of a flagellar biosynthesis operon (PF0329-PF0338).Consequently, cells in the mutant culture lacked flagella and, unlike the WT, showed minimal evidence of exopolysaccharide-based cell aggregation in post-exponential phase. Electron microscopy of PF0331-PF0337 deletions in P. furiosus COM1 showed that absence of flagella impacted normal cell aggregation behavior and, furthermore, indicated that flagella play a key role, beyond motility, in the growth physiology of P. furiosus.
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Affiliation(s)
- Derrick L Lewis
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, EB-1,911 Partners Way, Raleigh, NC, 27695-7905, US
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Akasaka N, Ishii Y, Hidese R, Sakoda H, Fujiwara S. Enhanced production of branched-chain amino acids by Gluconacetobacter europaeus with a specific regional deletion in a leucine responsive regulator. J Biosci Bioeng 2014; 118:607-15. [DOI: 10.1016/j.jbiosc.2014.05.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 05/21/2014] [Accepted: 05/29/2014] [Indexed: 10/25/2022]
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Plaisier CL, Lo FY, Ashworth J, Brooks AN, Beer KD, Kaur A, Pan M, Reiss DJ, Facciotti MT, Baliga NS. Evolution of context dependent regulation by expansion of feast/famine regulatory proteins. BMC SYSTEMS BIOLOGY 2014; 8:122. [PMID: 25394904 PMCID: PMC4236453 DOI: 10.1186/s12918-014-0122-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 10/16/2014] [Indexed: 11/25/2022]
Abstract
Background Expansion of transcription factors is believed to have played a crucial role in evolution of all organisms by enabling them to deal with dynamic environments and colonize new environments. We investigated how the expansion of the Feast/Famine Regulatory Protein (FFRP) or Lrp-like proteins into an eight-member family in Halobacterium salinarum NRC-1 has aided in niche-adaptation of this archaeon to a complex and dynamically changing hypersaline environment. Results We mapped genome-wide binding locations for all eight FFRPs, investigated their preference for binding different effector molecules, and identified the contexts in which they act by analyzing transcriptional responses across 35 growth conditions that mimic different environmental and nutritional conditions this organism is likely to encounter in the wild. Integrative analysis of these data constructed an FFRP regulatory network with conditionally active states that reveal how interrelated variations in DNA-binding domains, effector-molecule preferences, and binding sites in target gene promoters have tuned the functions of each FFRP to the environments in which they act. We demonstrate how conditional regulation of similar genes by two FFRPs, AsnC (an activator) and VNG1237C (a repressor), have striking environment-specific fitness consequences for oxidative stress management and growth, respectively. Conclusions This study provides a systems perspective into the evolutionary process by which gene duplication within a transcription factor family contributes to environment-specific adaptation of an organism. Electronic supplementary material The online version of this article (doi:10.1186/s12918-014-0122-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | - Fang-Yin Lo
- Institute for Systems Biology, Seattle, WA, USA. .,Molecular and Cellular Biology Program, University of Washington, Seattle, WA, USA.
| | | | - Aaron N Brooks
- Institute for Systems Biology, Seattle, WA, USA. .,Molecular and Cellular Biology Program, University of Washington, Seattle, WA, USA.
| | - Karlyn D Beer
- Institute for Systems Biology, Seattle, WA, USA. .,Molecular and Cellular Biology Program, University of Washington, Seattle, WA, USA.
| | | | - Min Pan
- Institute for Systems Biology, Seattle, WA, USA.
| | | | - Marc T Facciotti
- Department of Biomedical Engineering, University of California, Davis, CA, USA. .,Genome Center, University of California, Davis, CA, USA.
| | - Nitin S Baliga
- Institute for Systems Biology, Seattle, WA, USA. .,Molecular and Cellular Biology Program, University of Washington, Seattle, WA, USA. .,Department of Microbiology, University of Washington, Seattle, WA, USA. .,Department of Biology, University of Washington, Seattle, WA, USA.
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Ashworth J, Plaisier CL, Lo FY, Reiss DJ, Baliga NS. Inference of expanded Lrp-like feast/famine transcription factor targets in a non-model organism using protein structure-based prediction. PLoS One 2014; 9:e107863. [PMID: 25255272 PMCID: PMC4177876 DOI: 10.1371/journal.pone.0107863] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 08/16/2014] [Indexed: 11/18/2022] Open
Abstract
Widespread microbial genome sequencing presents an opportunity to understand the gene regulatory networks of non-model organisms. This requires knowledge of the binding sites for transcription factors whose DNA-binding properties are unknown or difficult to infer. We adapted a protein structure-based method to predict the specificities and putative regulons of homologous transcription factors across diverse species. As a proof-of-concept we predicted the specificities and transcriptional target genes of divergent archaeal feast/famine regulatory proteins, several of which are encoded in the genome of Halobacterium salinarum. This was validated by comparison to experimentally determined specificities for transcription factors in distantly related extremophiles, chromatin immunoprecipitation experiments, and cis-regulatory sequence conservation across eighteen related species of halobacteria. Through this analysis we were able to infer that Halobacterium salinarum employs a divergent local trans-regulatory strategy to regulate genes (carA and carB) involved in arginine and pyrimidine metabolism, whereas Escherichia coli employs an operon. The prediction of gene regulatory binding sites using structure-based methods is useful for the inference of gene regulatory relationships in new species that are otherwise difficult to infer.
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Affiliation(s)
- Justin Ashworth
- Institute for Systems Biology, Seattle, Washington, United States of America
- * E-mail: (JA); (NB)
| | | | - Fang Yin Lo
- Institute for Systems Biology, Seattle, Washington, United States of America
| | - David J. Reiss
- Institute for Systems Biology, Seattle, Washington, United States of America
| | - Nitin S. Baliga
- Institute for Systems Biology, Seattle, Washington, United States of America
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
- * E-mail: (JA); (NB)
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