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Pizzoni A, Zhang X, Altschuler DL. From membrane to nucleus: A three-wave hypothesis of cAMP signaling. J Biol Chem 2024; 300:105497. [PMID: 38016514 PMCID: PMC10788541 DOI: 10.1016/j.jbc.2023.105497] [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: 09/18/2023] [Revised: 11/14/2023] [Accepted: 11/19/2023] [Indexed: 11/30/2023] Open
Abstract
For many decades, our understanding of G protein-coupled receptor (GPCR) activity and cyclic AMP (cAMP) signaling was limited exclusively to the plasma membrane. However, a growing body of evidence has challenged this view by introducing the concept of endocytosis-dependent GPCR signaling. This emerging paradigm emphasizes not only the sustained production of cAMP but also its precise subcellular localization, thus transforming our understanding of the spatiotemporal organization of this process. Starting from this alternative point of view, our recent work sheds light on the role of an endocytosis-dependent calcium release from the endoplasmic reticulum in the control of nuclear cAMP levels. This is achieved through the activation of local soluble adenylyl cyclase, which in turn regulates the activation of local protein kinase A (PKA) and downstream transcriptional events. In this review, we explore the dynamic evolution of research on cyclic AMP signaling, including the findings that led us to formulate the novel three-wave hypothesis. We delve into how we abandoned the paradigm of cAMP generation limited to the plasma membrane and the changing perspectives on the rate-limiting step in nuclear PKA activation.
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Affiliation(s)
- Alejandro Pizzoni
- Department of Pharmacology and Chemical Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Xuefeng Zhang
- Department of Pharmacology and Chemical Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Daniel L Altschuler
- Department of Pharmacology and Chemical Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
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2
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Lang M, Carvalho A, Baharoglu Z, Mazel D. Aminoglycoside uptake, stress, and potentiation in Gram-negative bacteria: new therapies with old molecules. Microbiol Mol Biol Rev 2023; 87:e0003622. [PMID: 38047635 PMCID: PMC10732077 DOI: 10.1128/mmbr.00036-22] [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] [Indexed: 12/05/2023] Open
Abstract
SUMMARYAminoglycosides (AGs) are long-known molecules successfully used against Gram-negative pathogens. While their use declined with the discovery of new antibiotics, they are now classified as critically important molecules because of their effectiveness against multidrug-resistant bacteria. While they can efficiently cross the Gram-negative envelope, the mechanism of AG entry is still incompletely understood, although this comprehension is essential for the development of new therapies in the face of the alarming increase in antibiotic resistance. Increasing antibiotic uptake in bacteria is one strategy to enhance effective treatments. This review aims, first, to consolidate old and recent knowledge about AG uptake; second, to explore the connection between AG-dependent bacterial stress and drug uptake; and finally, to present new strategies of potentiation of AG uptake for more efficient antibiotic therapies. In particular, we emphasize on the connection between sugar transport and AG potentiation.
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Affiliation(s)
- Manon Lang
- Institut Pasteur, Université Paris Cité, CNRS UMR3525, Unité Plasticité du Génome Bactérien, Paris, France
| | - André Carvalho
- Institut Pasteur, Université Paris Cité, CNRS UMR3525, Unité Plasticité du Génome Bactérien, Paris, France
| | - Zeynep Baharoglu
- Institut Pasteur, Université Paris Cité, CNRS UMR3525, Unité Plasticité du Génome Bactérien, Paris, France
| | - Didier Mazel
- Institut Pasteur, Université Paris Cité, CNRS UMR3525, Unité Plasticité du Génome Bactérien, Paris, France
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3
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Fan Z, Fu T, Liu H, Li Z, Du B, Cui X, Zhang R, Feng Y, Zhao H, Xue G, Cui J, Yan C, Gan L, Feng J, Xu Z, Yu Z, Tian Z, Ding Z, Chen J, Chen Y, Yuan J. Glucose Induces Resistance to Polymyxins in High-Alcohol-Producing Klebsiella pneumoniae via Increasing Capsular Polysaccharide and Maintaining Intracellular ATP. Microbiol Spectr 2023; 11:e0003123. [PMID: 37338347 PMCID: PMC10434286 DOI: 10.1128/spectrum.00031-23] [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: 01/10/2023] [Accepted: 05/31/2023] [Indexed: 06/21/2023] Open
Abstract
High-alcohol-producing K. pneumoniae (HiAlc Kpn) causes nonalcoholic fatty liver disease (NAFLD) by producing excess endogenous alcohol in the gut of patients with NAFLD, using glucose as the main carbon source. The role of glucose in the response of HiAlc Kpn to environmental stresses such as antibiotics remains unclear. In this study, we found that glucose could enhance the resistance of HiAlc Kpn to polymyxins. First, glucose inhibited the expression of crp in HiAlc Kpn and promoted the increase of capsular polysaccharide (CPS), which promoted the drug resistance of HiAlc Kpn. Second, glucose maintained high ATP levels in HiAlc Kpn cells under the pressure of polymyxins, enhancing the resistance of the cells to the killing effect of antibiotics. Notably, the inhibition of CPS formation and the decrease of intracellular ATP levels could both effectively reverse glucose-induced polymyxins resistance. Our work demonstrated the mechanism by which glucose induces polymyxins resistance in HiAlc Kpn, thereby laying the foundation for developing effective treatments for NAFLD caused by HiAlc Kpn. IMPORTANCE HiAlc Kpn can use glucose to produce excess endogenous alcohol for promoting the development of NAFLD. Polymyxins are the last line of antibiotics and are commonly used to treat infections caused by carbapenem-resistant K. pneumoniae. In this study, we found that glucose increased bacterial resistance to polymyxins via increasing CPS and maintaining intracellular ATP; this increases the risk of failure to treat NAFLD caused by multidrug-resistant HiAlc Kpn infection. Further research revealed the important roles of glucose and the global regulator, CRP, in bacterial resistance and found that inhibiting CPS formation and decreasing intracellular ATP levels could effectively reverse glucose-induced polymyxins resistance. Our work reveals that glucose and the regulatory factor CRP can affect the resistance of bacteria to polymyxins, laying a foundation for the treatment of infections caused by multidrug-resistant bacteria.
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Affiliation(s)
- Zheng Fan
- Department of Bacteriology, Capital Institute of Pediatrics, Beijing, China
| | - Tongtong Fu
- Department of Bacteriology, Capital Institute of Pediatrics, Beijing, China
| | - Hongbo Liu
- School of Pharmaceutical Sciences, Jilin University, Changchun, China
| | - Zhoufei Li
- Department of Bacteriology, Capital Institute of Pediatrics, Beijing, China
| | - Bing Du
- University of Edinburgh, Edinburgh, United Kingdom
| | - Xiaohu Cui
- Department of Bacteriology, Capital Institute of Pediatrics, Beijing, China
| | - Rui Zhang
- Department of Bacteriology, Capital Institute of Pediatrics, Beijing, China
- Graduate School, Peking Union Medical College, Beijing, China
| | - Yanling Feng
- Department of Bacteriology, Capital Institute of Pediatrics, Beijing, China
| | - Hanqing Zhao
- Department of Bacteriology, Capital Institute of Pediatrics, Beijing, China
| | - Guanhua Xue
- Department of Bacteriology, Capital Institute of Pediatrics, Beijing, China
| | - Jinghua Cui
- Department of Bacteriology, Capital Institute of Pediatrics, Beijing, China
| | - Chao Yan
- Department of Bacteriology, Capital Institute of Pediatrics, Beijing, China
| | - Lin Gan
- Department of Bacteriology, Capital Institute of Pediatrics, Beijing, China
| | - Junxia Feng
- Department of Bacteriology, Capital Institute of Pediatrics, Beijing, China
| | - Ziying Xu
- Department of Bacteriology, Capital Institute of Pediatrics, Beijing, China
| | - Zihui Yu
- Department of Bacteriology, Capital Institute of Pediatrics, Beijing, China
| | - Ziyan Tian
- Department of Bacteriology, Capital Institute of Pediatrics, Beijing, China
| | - Zanbo Ding
- Department of Bacteriology, Capital Institute of Pediatrics, Beijing, China
| | - Jinfeng Chen
- Department of Bacteriology, Capital Institute of Pediatrics, Beijing, China
| | - Yujie Chen
- Department of Bacteriology, Capital Institute of Pediatrics, Beijing, China
| | - Jing Yuan
- Department of Bacteriology, Capital Institute of Pediatrics, Beijing, China
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4
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Zakrzewska M, Burmistrz M. Mechanisms regulating the CRISPR-Cas systems. Front Microbiol 2023; 14:1060337. [PMID: 36925473 PMCID: PMC10013973 DOI: 10.3389/fmicb.2023.1060337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 02/10/2023] [Indexed: 03/08/2023] Open
Abstract
The CRISPR-Cas (Clustered Regularly Interspaced Short Palindromic Repeats- CRISPR associated proteins) is a prokaryotic system that enables sequence specific recognition and cleavage of nucleic acids. This is possible due to cooperation between CRISPR array which contains short fragments of DNA called spacers that are complimentary to the targeted nucleic acid and Cas proteins, which take part in processes of: acquisition of new spacers, processing them into their functional form as well as recognition and cleavage of targeted nucleic acids. The primary role of CRISPR-Cas systems is to provide their host with an adaptive and hereditary immunity against exogenous nucleic acids. This system is present in many variants in both Bacteria and Archea. Due to its modular structure, and programmability CRISPR-Cas system become attractive tool for modern molecular biology. Since their discovery and implementation, the CRISPR-Cas systems revolutionized areas of gene editing and regulation of gene expression. Although our knowledge on how CRISPR-Cas systems work has increased rapidly in recent years, there is still little information on how these systems are controlled and how they interact with other cellular mechanisms. Such regulation can be the result of both auto-regulatory mechanisms as well as exogenous proteins of phage origin. Better understanding of these interaction networks would be beneficial for optimization of current and development of new CRISPR-Cas-based tools. In this review we summarize current knowledge on the various molecular mechanisms that affect activity of CRISPR-Cas systems.
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Affiliation(s)
- Marta Zakrzewska
- Department of Environmental Microbiology and Biotechnology, Faculty of Biology, Institute of Microbiology, University of Warsaw, Warsaw, Poland.,Department of Molecular Microbiology, Biological and Chemical Research Centre, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Michal Burmistrz
- Department of Molecular Microbiology, Biological and Chemical Research Centre, Faculty of Biology, University of Warsaw, Warsaw, Poland.,Centre of New Technologies, University of Warsaw, Warsaw, Poland
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Lauritsen I, Frendorf PO, Capucci S, Heyde SAH, Blomquist SD, Wendel S, Fischer EC, Sekowska A, Danchin A, Nørholm MHH. Temporal evolution of master regulator Crp identifies pyrimidines as catabolite modulator factors. Nat Commun 2021; 12:5880. [PMID: 34620864 PMCID: PMC8497467 DOI: 10.1038/s41467-021-26098-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 09/07/2021] [Indexed: 12/19/2022] Open
Abstract
The evolution of microorganisms often involves changes of unclear relevance, such as transient phenotypes and sequential development of multiple adaptive mutations in hotspot genes. Previously, we showed that ageing colonies of an E. coli mutant unable to produce cAMP when grown on maltose, accumulated mutations in the crp gene (encoding a global transcription factor) and in genes involved in pyrimidine metabolism such as cmk; combined mutations in both crp and cmk enabled fermentation of maltose (which usually requires cAMP-mediated Crp activation for catabolic pathway expression). Here, we study the sequential generation of hotspot mutations in those genes, and uncover a regulatory role of pyrimidine nucleosides in carbon catabolism. Cytidine binds to the cytidine regulator CytR, modifies the expression of sigma factor 32 (RpoH), and thereby impacts global gene expression. In addition, cytidine binds and activates a Crp mutant directly, thus modulating catabolic pathway expression, and could be the catabolite modulating factor whose existence was suggested by Jacques Monod and colleagues in 1976. Therefore, transcription factor Crp appears to work in concert with CytR and RpoH, serving a dual role in sensing both carbon availability and metabolic flux towards DNA and RNA. Our findings show how certain alterations in metabolite concentrations (associated with colony ageing and/or due to mutations in metabolic or regulatory genes) can drive the evolution in non-growing cells. Microbial evolution often involves transient phenotypes and sequential development of multiple mutations of unclear relevance. Here, the authors show that the evolution of non-growing E. coli cells can be driven by alterations in pyrimidine nucleoside levels associated with colony ageing and/or due to mutations in metabolic or regulatory genes.
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Affiliation(s)
- Ida Lauritsen
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark
| | - Pernille Ott Frendorf
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark
| | - Silvia Capucci
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark
| | - Sophia A H Heyde
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark
| | - Sarah D Blomquist
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark
| | - Sofie Wendel
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark
| | - Emil C Fischer
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark
| | | | | | - Morten H H Nørholm
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark.
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Abstract
Bacteria thrive both in liquids and attached to surfaces. The concentration of bacteria on surfaces is generally much higher than in the surrounding environment, offering bacteria ample opportunity for mutualistic, symbiotic, and pathogenic interactions. To efficiently populate surfaces, they have evolved mechanisms to sense mechanical or chemical cues upon contact with solid substrata. This is of particular importance for pathogens that interact with host tissue surfaces. In this review we discuss how bacteria are able to sense surfaces and how they use this information to adapt their physiology and behavior to this new environment. We first survey mechanosensing and chemosensing mechanisms and outline how specific macromolecular structures can inform bacteria about surfaces. We then discuss how mechanical cues are converted to biochemical signals to activate specific cellular processes in a defined chronological order and describe the role of two key second messengers, c-di-GMP and cAMP, in this process.
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Affiliation(s)
| | - Urs Jenal
- Biozentrum, University of Basel, CH-4056 Basel, Switzerland; ,
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7
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Pan Q, Li Z, Ju X, Hou C, Xiao Y, Shi R, Fu C, Danchin A, You C. Escherichia coli segments its controls on carbon-dependent gene expression into global and specific regulations. Microb Biotechnol 2021; 14:1084-1106. [PMID: 33650807 PMCID: PMC8085971 DOI: 10.1111/1751-7915.13776] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 02/05/2021] [Accepted: 02/05/2021] [Indexed: 01/20/2023] Open
Abstract
How bacteria adjust gene expression to cope with variable environments remains open to question. Here, we investigated the way global gene expression changes in E. coli correlated with the metabolism of seven carbon substrates chosen to trigger a large panel of metabolic pathways. Coarse-grained analysis of gene co-expression identified a novel regulation pattern: we established that the gene expression trend following immediately the reduction of growth rate (GR) was correlated to its initial expression level. Subsequent fine-grained analysis of co-expression demonstrated that the Crp regulator, coupled with a change in GR, governed the response of most GR-dependent genes. By contrast, the Cra, Mlc and Fur regulators governed the expression of genes responding to non-glycolytic substrates, glycolytic substrates or phosphotransferase system transported sugars following an idiosyncratic way. This work allowed us to expand additional genes in the panel of gene complement regulated by each regulator and to elucidate the regulatory functions of each regulator comprehensively. Interestingly, the bulk of genes controlled by Cra and Mlc were, respectively, co-regulated by Crp- or GR-related effect and our quantitative analysis showed that each factor took turns to work as the primary one or contributed equally depending on the conditions.
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Affiliation(s)
- Qing Pan
- Shenzhen Key Laboratory of Microbial Genetic EngineeringCollege of Life Sciences and OceanologyShenzhen UniversityShenzhen, GuangdongChina
- Shandong Provincial Key Laboratory of Energy GeneticsKey Laboratory of BiofuelsQingdao Engineering Research Center of Biomass Resources and EnvironmentQingdao Institute of Bioenergy and Bioprocess TechnologyChinese Academy of SciencesQingdao, ShandongChina
| | - Zongjin Li
- Shenzhen Key Laboratory of Microbial Genetic EngineeringCollege of Life Sciences and OceanologyShenzhen UniversityShenzhen, GuangdongChina
| | - Xian Ju
- Shenzhen Key Laboratory of Microbial Genetic EngineeringCollege of Life Sciences and OceanologyShenzhen UniversityShenzhen, GuangdongChina
| | - Chaofan Hou
- Shenzhen Key Laboratory of Microbial Genetic EngineeringCollege of Life Sciences and OceanologyShenzhen UniversityShenzhen, GuangdongChina
| | - Yunzhu Xiao
- Shenzhen Key Laboratory of Microbial Genetic EngineeringCollege of Life Sciences and OceanologyShenzhen UniversityShenzhen, GuangdongChina
| | - Ruoping Shi
- Shenzhen Key Laboratory of Microbial Genetic EngineeringCollege of Life Sciences and OceanologyShenzhen UniversityShenzhen, GuangdongChina
| | - Chunxiang Fu
- Shandong Provincial Key Laboratory of Energy GeneticsKey Laboratory of BiofuelsQingdao Engineering Research Center of Biomass Resources and EnvironmentQingdao Institute of Bioenergy and Bioprocess TechnologyChinese Academy of SciencesQingdao, ShandongChina
| | - Antoine Danchin
- Kodikos Labs/Stellate TherapeuticsInstitut Cochin24 rue du Faubourg Saint‐JacquesParis75014France
| | - Conghui You
- Shenzhen Key Laboratory of Microbial Genetic EngineeringCollege of Life Sciences and OceanologyShenzhen UniversityShenzhen, GuangdongChina
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8
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Thompson CM, Malone JG. Nucleotide second messengers in bacterial decision making. Curr Opin Microbiol 2020; 55:34-39. [PMID: 32172083 PMCID: PMC7322531 DOI: 10.1016/j.mib.2020.02.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 02/04/2020] [Accepted: 02/10/2020] [Indexed: 12/28/2022]
Abstract
Structural analysis of NSM regulators reveals new mechanisms of NSM signalling. NSM proteins binding multiple ligands support crosstalk between signalling networks. NSM networks control structure and heterogeneity in complex microbial communities. The diversity of bacterial NSM regulators is far higher than previously thought. The (p)ppApp toxin suggests non-signalling roles exist for bacterial NSMs.
Since the initial discovery of bacterial nucleotide second messengers (NSMs), we have made huge progress towards understanding these complex signalling networks. Many NSM networks contain dozens of metabolic enzymes and binding targets, whose activity is tightly controlled at every regulatory level. They function as global regulators and in specific signalling circuits, controlling multiple aspects of bacterial behaviour and development. Despite these advances there is much still to discover, with current research focussing on the molecular mechanisms of signalling circuits, the role of the environment in controlling NSM pathways and attempts to understand signalling at the whole cell/community level. Here we examine recent developments in the NSM signalling field and discuss their implications for understanding this important driver of microbial behaviour.
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Affiliation(s)
- Catriona Ma Thompson
- Molecular Microbiology Department, John Innes Centre, Norwich, UK; School of Biological Sciences, University of East Anglia, Norwich, UK
| | - Jacob G Malone
- Molecular Microbiology Department, John Innes Centre, Norwich, UK; School of Biological Sciences, University of East Anglia, Norwich, UK.
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Li Z, Pan Q, Xiao Y, Fang X, Shi R, Fu C, Danchin A, You C. Deciphering global gene expression and regulation strategy in Escherichia coli during carbon limitation. Microb Biotechnol 2019; 12:360-376. [PMID: 30536863 PMCID: PMC6390033 DOI: 10.1111/1751-7915.13343] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 11/04/2018] [Accepted: 11/07/2018] [Indexed: 12/01/2022] Open
Abstract
Despite decades of studies meant to analyse the bacterial response to carbon limitation, we still miss a high-resolution overview of the situation. All gene expression changes observed in such conditions cannot solely be accounted for by the global regulator Crp either free or bound to its effector, cyclic AMP. Here, for the first time, we evaluated the response of both CDS (protein-coding sequence) and ncRNA (non-coding RNA) genes to carbon limitation, revealed cellular functions of differentially expressed genes systematically, quantified the contribution of Crp-cAMP and other factors to regulation and deciphered regulation strategies at a genomewide scale. Approximately one-third of the differentially expressed genes we identified responded to Crp-cAMP via its direct or indirect control, while the remaining genes were subject to growth rate-dependent control or were controlled by other regulators, especially RpoS. Importantly, gene regulation mechanisms can be established by expression pattern studies. Here, we propose a comprehensive picture of how cells respond to carbon scarcity. The global regulation strategies thus exposed illustrate that the response of cell to carbon scarcity is not limited to maintaining sufficient carbon metabolism via cAMP signalling while the main response is to adjust metabolism to cope with a slow growth rate.
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Affiliation(s)
- Zongjin Li
- Shenzhen Key Laboratory of Microbial Genetic EngineeringCollege of Life Sciences and OceanologyShenzhen University1066 Xueyuan RdShenzhen518055GuangdongP. R. China
| | - Qing Pan
- Shenzhen Key Laboratory of Microbial Genetic EngineeringCollege of Life Sciences and OceanologyShenzhen University1066 Xueyuan RdShenzhen518055GuangdongP. R. China
- Shandong Provincial Key Laboratory of Energy GeneticsKey Laboratory of BiofuelsQingdao Engineering Research Center of Biomass Resources and EnvironmentQingdao Institute of Bioenergy and Bioprocess TechnologyChinese Academy of Sciences189 Songling RdQingdao266101ShandongP. R.China
| | - Yunzhu Xiao
- Shenzhen Key Laboratory of Microbial Genetic EngineeringCollege of Life Sciences and OceanologyShenzhen University1066 Xueyuan RdShenzhen518055GuangdongP. R. China
| | - Xingxing Fang
- Shenzhen Key Laboratory of Microbial Genetic EngineeringCollege of Life Sciences and OceanologyShenzhen University1066 Xueyuan RdShenzhen518055GuangdongP. R. China
| | - Ruoping Shi
- Shenzhen Key Laboratory of Microbial Genetic EngineeringCollege of Life Sciences and OceanologyShenzhen University1066 Xueyuan RdShenzhen518055GuangdongP. R. China
| | - Chunxiang Fu
- Shandong Provincial Key Laboratory of Energy GeneticsKey Laboratory of BiofuelsQingdao Engineering Research Center of Biomass Resources and EnvironmentQingdao Institute of Bioenergy and Bioprocess TechnologyChinese Academy of Sciences189 Songling RdQingdao266101ShandongP. R.China
| | - Antoine Danchin
- IntegromicsInstitute of Cardiometabolism and NutritionHôpital de la Pitié‐Salpêtrière47 Boulevard de l'Hôpital75013ParisFrance
- School of Biomedical SciencesLi KaShing Faculty of MedicineHong Kong University21 Sassoon RoadPokfulamHong Kong
| | - Conghui You
- Shenzhen Key Laboratory of Microbial Genetic EngineeringCollege of Life Sciences and OceanologyShenzhen University1066 Xueyuan RdShenzhen518055GuangdongP. R. China
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10
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Synbiotic combination of Lactobacillus rhamnosus NCDC 298 and short chain fructooligosaccharides prevents enterotoxigenic Escherichia coli infection. Lebensm Wiss Technol 2018. [DOI: 10.1016/j.lwt.2018.08.061] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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11
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Malhotra N, Karthikeyan S, Chakraborti PK. Phosphorylation of mycobacterial phosphodiesterase by eukaryotic-type Ser/Thr kinase controls its two distinct and mutually exclusive functionalities. J Biol Chem 2017; 292:17362-17374. [PMID: 28855253 DOI: 10.1074/jbc.m117.784124] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 08/03/2017] [Indexed: 02/05/2023] Open
Abstract
Phosphorylation-mediated negative feedback regulation of cAMP levels by phosphodiesterase is well-established in eukaryotic cells. However, such a mechanism remains unexplored in prokaryotes. We report here the involvement of eukaryotic-type Ser/Thr kinases, particularly PknA in trans-phosphorylating phosphodiesterase from Mycobacterium tuberculosis (mPDE), that resulted in decreased enzyme turnover rate compared with its unphosphorylated counterpart. To elucidate the role of mPDE phosphorylation in hydrolyzing cellular cAMP, we utilized a phosphodiesterase knock-out Escherichia coli strain, ΔcpdA, where interference of endogenous eukaryotic-type Ser/Thr kinases could be excluded. Interestingly, the mPDE-complemented ΔcpdA strain showed enhanced cAMP levels in the presence of PknA, and this effect was antagonized by PknA-K42N, a kinase-dead variant. Structural analysis of mPDE revealed that four Ser/Thr residues (Ser-20, Thr-22, Thr-182, and Thr-240) were close to the active site, indicating their possible role in phosphorylation-mediated alteration in enzymatic activity. Mutation of these residues one at a time to alanine or a combination of all four (mPDE-4A) affected catalytic activity of mPDE. Moreover, mPDE-4A protein in kinase assays exhibited reduction in its phosphorylation compared with mPDE. In consonance, phosphoproteins obtained after co-expression of PknA with mPDE/S20A/T240A/4A displayed decreased phospho-signal intensities in immunoblotting with anti-phosphoserine/phosphothreonine antibodies. Furthermore, unlike mPDE, phospho-ablated mPDE-T309A protein exhibited impaired cell wall localization in Mycobacterium smegmatis, whereas mPDE-4A behaved similarly as wild type. Taken together, our findings establish mutually exclusive dual functionality of mPDE upon PknA-mediated phosphorylation, where Ser-20/Thr-240 influence enzyme activity and Thr-309 endorses its cell wall localization.
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Affiliation(s)
- Neha Malhotra
- From the Council of Scientific and Industrial Research-Institute of Microbial Technology, Sector 39A, Chandigarh 160 036, India
| | - Subramanian Karthikeyan
- From the Council of Scientific and Industrial Research-Institute of Microbial Technology, Sector 39A, Chandigarh 160 036, India
| | - Pradip K Chakraborti
- From the Council of Scientific and Industrial Research-Institute of Microbial Technology, Sector 39A, Chandigarh 160 036, India
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12
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Patterson AG, Chang JT, Taylor C, Fineran PC. Regulation of the Type I-F CRISPR-Cas system by CRP-cAMP and GalM controls spacer acquisition and interference. Nucleic Acids Res 2015; 43:6038-48. [PMID: 26007654 PMCID: PMC4499141 DOI: 10.1093/nar/gkv517] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 05/06/2015] [Indexed: 12/22/2022] Open
Abstract
The CRISPR-Cas prokaryotic ‘adaptive immune systems’ represent a sophisticated defence strategy providing bacteria and archaea with protection from invading genetic elements, such as bacteriophages or plasmids. Despite intensive research into their mechanism and application, how CRISPR-Cas systems are regulated is less clear, and nothing is known about the regulation of Type I-F systems. We used Pectobacterium atrosepticum, a Gram-negative phytopathogen, to study CRISPR-Cas regulation, since it contains a single Type I-F system. The CRP-cAMP complex activated the cas operon, increasing the expression of the adaptation genes cas1 and cas2–3 in addition to the genes encoding the Csy surveillance complex. Mutation of crp or cyaA (encoding adenylate cyclase) resulted in reductions in both primed spacer acquisition and interference. Furthermore, we identified a galactose mutarotase, GalM, which reduced cas operon expression in a CRP- and CyaA-dependent manner. We propose that the Type I-F system senses metabolic changes, such as sugar availability, and regulates cas genes to initiate an appropriate defence response. Indeed, elevated glucose levels reduced cas expression in a CRP- and CyaA-dependent manner. Taken together, these findings highlight that a metabolite-sensing regulatory pathway controls expression of the Type I-F CRISPR-Cas system to modulate levels of adaptation and interference.
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Affiliation(s)
- Adrian G Patterson
- Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - James T Chang
- Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Corinda Taylor
- Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Peter C Fineran
- Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
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Dey B, Bishai WR. Crosstalk between Mycobacterium tuberculosis and the host cell. Semin Immunol 2014; 26:486-96. [PMID: 25303934 DOI: 10.1016/j.smim.2014.09.002] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 09/02/2014] [Indexed: 11/15/2022]
Abstract
The successful establishment and maintenance of a bacterial infection depend on the pathogen's ability to subvert the host cell's defense response and successfully survive, proliferate, or persist within the infected cell. To circumvent host defense systems, bacterial pathogens produce a variety of virulence factors that potentiate bacterial adherence and invasion and usurp host cell signaling cascades that regulate intracellular microbial survival and trafficking. Mycobacterium tuberculosis, probably one of the most successful pathogens on earth, has coexisted with humanity for centuries, and this intimate and persistent connection between these two organisms suggests that the pathogen has evolved extensive mechanisms to evade the human immune system at multiple levels. While some of these mechanisms are mediated by factors released by M. tuberculosis, others rely on host components that are hijacked to prevent the generation of an effective immune response thus benefiting the survival of M. tuberculosis within the host cell. Here, we describe several of these mechanisms, with an emphasis on the cyclic nucleotide signaling and subversion of host responses that occur at the intracellular level when tubercle bacilli encounter macrophages, a cell that becomes a safe-house for M. tuberculosis although it is specialized to kill most microbes.
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Affiliation(s)
- Bappaditya Dey
- Department of Medicine, Johns Hopkins University, School of Medicine, Baltimore, MD, USA; Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - William R Bishai
- Department of Medicine, Johns Hopkins University, School of Medicine, Baltimore, MD, USA; Howard Hughes Medical Institute, Chevy Chase, MD, USA.
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14
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Coordination of bacterial proteome with metabolism by cyclic AMP signalling. Nature 2013; 500:301-6. [PMID: 23925119 DOI: 10.1038/nature12446] [Citation(s) in RCA: 269] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Accepted: 07/11/2013] [Indexed: 11/08/2022]
Abstract
The cyclic AMP (cAMP)-dependent catabolite repression effect in Escherichia coli is among the most intensely studied regulatory processes in biology. However, the physiological function(s) of cAMP signalling and its molecular triggers remain elusive. Here we use a quantitative physiological approach to show that cAMP signalling tightly coordinates the expression of catabolic proteins with biosynthetic and ribosomal proteins, in accordance with the cellular metabolic needs during exponential growth. The expression of carbon catabolic genes increased linearly with decreasing growth rates upon limitation of carbon influx, but decreased linearly with decreasing growth rate upon limitation of nitrogen or sulphur influx. In contrast, the expression of biosynthetic genes showed the opposite linear growth-rate dependence as the catabolic genes. A coarse-grained mathematical model provides a quantitative framework for understanding and predicting gene expression responses to catabolic and anabolic limitations. A scheme of integral feedback control featuring the inhibition of cAMP signalling by metabolic precursors is proposed and validated. These results reveal a key physiological role of cAMP-dependent catabolite repression: to ensure that proteomic resources are spent on distinct metabolic sectors as needed in different nutrient environments. Our findings underscore the power of quantitative physiology in unravelling the underlying functions of complex molecular signalling networks.
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ANDO T, ITOH S, YAMATO I. Development of Cell Systems Simulator Using Biochemical Data. JOURNAL OF COMPUTER CHEMISTRY-JAPAN 2013. [DOI: 10.2477/jccj.2013-0018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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16
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SMITH JL, BENCIVENGO MM, BUCHANAN RL, KUNSCH CA. EFFECT OF GLUCOSE ANALOGS ON THE SYNTHESIS OF STAPHYLOCOCCAL ENTEROTOXIN A. J Food Saf 2007. [DOI: 10.1111/j.1745-4565.1986.tb00559.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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17
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Deutscher J, Francke C, Postma PW. How phosphotransferase system-related protein phosphorylation regulates carbohydrate metabolism in bacteria. Microbiol Mol Biol Rev 2007; 70:939-1031. [PMID: 17158705 PMCID: PMC1698508 DOI: 10.1128/mmbr.00024-06] [Citation(s) in RCA: 989] [Impact Index Per Article: 58.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The phosphoenolpyruvate(PEP):carbohydrate phosphotransferase system (PTS) is found only in bacteria, where it catalyzes the transport and phosphorylation of numerous monosaccharides, disaccharides, amino sugars, polyols, and other sugar derivatives. To carry out its catalytic function in sugar transport and phosphorylation, the PTS uses PEP as an energy source and phosphoryl donor. The phosphoryl group of PEP is usually transferred via four distinct proteins (domains) to the transported sugar bound to the respective membrane component(s) (EIIC and EIID) of the PTS. The organization of the PTS as a four-step phosphoryl transfer system, in which all P derivatives exhibit similar energy (phosphorylation occurs at histidyl or cysteyl residues), is surprising, as a single protein (or domain) coupling energy transfer and sugar phosphorylation would be sufficient for PTS function. A possible explanation for the complexity of the PTS was provided by the discovery that the PTS also carries out numerous regulatory functions. Depending on their phosphorylation state, the four proteins (domains) forming the PTS phosphorylation cascade (EI, HPr, EIIA, and EIIB) can phosphorylate or interact with numerous non-PTS proteins and thereby regulate their activity. In addition, in certain bacteria, one of the PTS components (HPr) is phosphorylated by ATP at a seryl residue, which increases the complexity of PTS-mediated regulation. In this review, we try to summarize the known protein phosphorylation-related regulatory functions of the PTS. As we shall see, the PTS regulation network not only controls carbohydrate uptake and metabolism but also interferes with the utilization of nitrogen and phosphorus and the virulence of certain pathogens.
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Affiliation(s)
- Josef Deutscher
- Microbiologie et Génétique Moléculaire, INRA-CNRS-INA PG UMR 2585, Thiverval-Grignon, France.
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18
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Morita T, El-Kazzaz W, Tanaka Y, Inada T, Aiba H. Accumulation of glucose 6-phosphate or fructose 6-phosphate is responsible for destabilization of glucose transporter mRNA in Escherichia coli. J Biol Chem 2003; 278:15608-14. [PMID: 12578824 DOI: 10.1074/jbc.m300177200] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Previously we found that a mutation in either pgi or pfkA, encoding phosphoglucose isomerase or phosphofructokinase A, respectively, facilitates degradation of the ptsG mRNA in an RNase E-dependent manner in Escherichia coli (1). In this study, we examined the effects of a series of glycolytic genes on the degradation of ptsG mRNA and how the mutations destabilize the ptsG mRNA. The conditional lethal mutation ts8 in fda, encoding fructose-1,6-P(2) aldolase just downstream of pfkA in the glycolytic pathway, caused the destabilization of ptsG mRNA at the nonpermissive temperature. Mutations in any other gene did not destabilize the ptsG mRNA; rather, they reduced the ptsG transcription mainly by affecting the cAMP level. The rapid degradation of ptsG mRNA in mutant strains was completely dependent upon the presence of glucose or any one of its compounds, which enter the Embden-Meyerhof glycolytic pathway before the block points. A significant increase in the intracellular glucose-6-P level was observed in the presence of glucose in the pgi strain. An overexpression of glucose-6-phosphate dehydrogenase eliminated both the accumulation and the degradation of ptsG mRNA in the pgi strain. In addition, accumulation of fructose-6-P led to the rapid degradation of ptsG mRNA in a pgi pfkA mutant strain lacking glucose-6-P. We conclude that the RNase E-dependent destabilization of ptsG mRNA occurs in response to accumulation of glucose-6-P or fructose-6-P.
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Affiliation(s)
- Teppei Morita
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa, Nagoya 464-8602, Japan
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19
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Hogema BM, Arents JC, Bader R, Eijkemans K, Yoshida H, Takahashi H, Aiba H, Postma PW. Inducer exclusion in Escherichia coli by non-PTS substrates: the role of the PEP to pyruvate ratio in determining the phosphorylation state of enzyme IIAGlc. Mol Microbiol 1998; 30:487-98. [PMID: 9822815 DOI: 10.1046/j.1365-2958.1998.01053.x] [Citation(s) in RCA: 172] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The main mechanism causing catabolite repression in Escherichia coli is the dephosphorylation of enzyme IIAGlc, one of the enzymes of the phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS). The PTS is involved in the uptake of a large number of carbohydrates that are phosphorylated during transport, phosphoenolpyruvate (PEP) being the phosphoryl donor. Dephosphorylation of enzyme IIAGlc causes inhibition of uptake of a number of non-PTS carbon sources, a process called inducer exclusion. In this paper, we show that dephosphorylation of enzyme IIAGlc is not only caused by the transport of PTS carbohydrates, as has always been thought, and that an additional mechanism causing dephosphorylation exists. Direct monitoring of the phosphorylation state of enzyme IIAGlc also showed that many carbohydrates that are not transported by the PTS caused dephosphorylation during growth. In the case of glucose 6-phosphate, it was shown that transport and the first metabolic step are not involved in the dephosphorylation of enzyme IIAGlc, but that later steps in the glycolysis are essential. Evidence is provided that the [PEP]-[pyruvate] ratio, the driving force for the phosphorylation of the PTS proteins, determines the phosphorylation state of enzyme IIAGlc. The implications of these new findings for our view on catabolite repression and inducer exclusion are discussed.
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Affiliation(s)
- B M Hogema
- E.C. Slater Institute, BioCentrum, University of Amsterdam, Plantage Muidergracht 12, 1018 TV Amsterdam, The Netherlands
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20
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Lee DC, Kim GJ, Cha YK, Lee CY, Kim HS. Mass production of thermostable D-hydantoinase by batch culture of recombinantEscherichia coli with a constitutive expression system. Biotechnol Bioeng 1997; 56:449-55. [DOI: 10.1002/(sici)1097-0290(19971120)56:4<449::aid-bit10>3.0.co;2-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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21
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Notley-McRobb L, Death A, Ferenci T. The relationship between external glucose concentration and cAMP levels inside Escherichia coli: implications for models of phosphotransferase-mediated regulation of adenylate cyclase. MICROBIOLOGY (READING, ENGLAND) 1997; 143 ( Pt 6):1909-1918. [PMID: 9202467 DOI: 10.1099/00221287-143-6-1909] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The concentration of glucose in the medium influences the regulation of cAMP levels in Escherichia coli. Growth in minimal medium with micromolar glucose results in 8- to 10-fold higher intracellular cAMP concentrations than observed during growth with excess glucose. Current models would suggest that the difference in cAMP levels between glucose-rich and glucose-limited states is due to altered transport flux through the phosphoenolpyruvate: glucose phosphotransferase system (PTS), which in turn controls adenylate cyclase. A consequence of this model is that cAMP levels should be inversely related to the saturation of the PTS transporter. To test this hypothesis, the relationship between external glucose concentration and cAMP levels inside E. coli were investigated in detail, both through direct cAMP assay and indirectly through measurement of expression of cAMP-regulated genes. Responses were followed in batch, dialysis and glucose-limited continuous culture. A sharp rise in intracellular cAMP occurred when the nutrient concentration in minimal medium dropped to approximately 0.3 mM glucose. Likewise, addition of > 0.3 mM glucose, but not < 0.3 mM glucose, sharply reduced the intracellular cAMP level of starving bacteria. There was no striking shift in growth rate or [14C] glucose assimilation in bacteria passing through the 0.5 to 0.3 mM concentration threshold influencing cAMP levels, suggesting that neither metabolic flux nor transporter saturation influenced the sensing of nutrient levels. The (IIA/IIBC)Glc PTS is 96-97% saturated at 0.3 mM glucose so these results are not easily reconcilable with current models of cAMP regulation. Aside from the transition in cAMP levels initiated above 0.3 mM, a second shift occurred below 1 muM glucose. Approaching starvation, well below saturation of the PTS, cAMP levels either increased or decreased depending on unknown factors that differ between common E. coli K-12 strains.
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Affiliation(s)
- Lucinda Notley-McRobb
- Department of Microbiology G08, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Alison Death
- Department of Microbiology G08, University of Sydney, Sydney, New South Wales 2006, Australia
| | - Thomas Ferenci
- Department of Microbiology G08, University of Sydney, Sydney, New South Wales 2006, Australia
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22
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Affiliation(s)
- M Crasnier
- University of California San Diego, Department of Biology, La Jolla 92093-0116, USA
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23
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Ishizuka H, Hanamura A, Kunimura T, Aiba H. A lowered concentration of cAMP receptor protein caused by glucose is an important determinant for catabolite repression in Escherichia coli. Mol Microbiol 1993; 10:341-50. [PMID: 7934825 DOI: 10.1111/j.1365-2958.1993.tb01960.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A decreased intracellular concentration of cAMP is insufficient to account for catabolite repression in Escherichia coli. We show that glucose lowers the amount of cAMP receptor protein (CRP) in cells. A correlation exists between CRP and beta-galactosidase levels in cells growing under various conditions. Exogenous cAMP completely eliminates catabolite repression in CRP-overproducing cells, while it does not fully reverse the effect of glucose on beta-galactosidase expression in wild-type cells. When the CRP concentration is reduced by manipulating the crp gene, beta-galactosidase expression decreases in proportion to the concentration of CRP. These findings indicate that the lowered concentration of CRP caused by glucose is one of the major factors for catabolite repression. We propose that glucose causes catabolite repression by lowering the intracellular levels of both CRP and cAMP.
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Affiliation(s)
- H Ishizuka
- Department of Molecular Biology, School of Science, Nagoya University, Japan
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24
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Abstract
The relationship between retroviral genes and oncogenes is described
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Affiliation(s)
- H E Varmus
- Department of Microbiology and Immunology, University of California, San Francisco 94143
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25
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26
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Biswas SR, Mishra AK, Nanda G. Induction of xylanase inAspergillus ochraceus. Folia Microbiol (Praha) 1988. [DOI: 10.1007/bf02925844] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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27
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Balke VL, Gralla JD. Changes in the linking number of supercoiled DNA accompany growth transitions in Escherichia coli. J Bacteriol 1987; 169:4499-506. [PMID: 3308843 PMCID: PMC213814 DOI: 10.1128/jb.169.10.4499-4506.1987] [Citation(s) in RCA: 212] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The supercoiling levels of plasmid DNA were determined from Escherichia coli which was grown in ways that are known to alter global patterns of gene expression and metabolism. Changes in DNA supercoiling were shown to occur during several types of these nutrient upshifts and downshifts. The most dramatic change in supercoiling was seen in starved cells, in which two populations of differentially relaxed plasmids were shown to coexist. Thus, some changes in the external nutritional environment that cause the cells to reorganize their global metabolism also cause accompanying changes in DNA supercoiling. Results of experiments with dinitrophenol suggested that the observed relaxations were probably not due to reduced pools of ATP. When rifampin was used to release supercoils restrained by RNA polymerase, the cellular topoisomerases responded by removing these new, unrestrained supercoils. We interpret these results as implying that the cellular topological machinery maintains a constant superhelical energy in the DNA except during certain growth transitions, when changes in metabolism and gene expression are accompanied by changes in DNA supercoiling.
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MESH Headings
- 2,4-Dinitrophenol
- Acetates/metabolism
- Culture Media
- DNA, Bacterial/drug effects
- DNA, Bacterial/genetics
- DNA, Bacterial/metabolism
- DNA, Superhelical/drug effects
- DNA, Superhelical/genetics
- DNA, Superhelical/metabolism
- Dinitrophenols/pharmacology
- Electrophoresis, Agar Gel
- Escherichia coli/genetics
- Escherichia coli/growth & development
- Escherichia coli/metabolism
- Gene Expression Regulation
- Genes, Bacterial
- Genetic Linkage
- Glucose/metabolism
- Nucleic Acid Conformation
- Plasmids
- Rifampin/pharmacology
- Transcription, Genetic
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Affiliation(s)
- V L Balke
- Department of Chemistry and Biochemistry, University of California, Los Angeles 90024
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28
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Mukherjee A, Ghosh S. Regulation of fructose uptake and catabolism by succinate in Azospirillum brasilense. J Bacteriol 1987; 169:4361-7. [PMID: 2957360 PMCID: PMC213753 DOI: 10.1128/jb.169.9.4361-4367.1987] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Fructose uptake and catabolism in Azospirillum brasilense is dependent on three fructose-inducible enzymes (fru-enzymes): (i) enzyme I and (ii) enzyme II of the phosphoenolpyruvate:fructose phosphotransferase system and (iii) 1-phosphofructokinase. In minimal medium containing 3.7 mM succinate and 22 mM fructose as sources of carbon, growth of A. brasilense was diauxic, succinate being utilized in the first phase of growth and fructose in the second phase with a lag period between the two growth phases. None of the fru-enzymes could be detected in cells grown with succinate as the sole source of carbon, but they were detectable toward the end of the first phase of diauxie. All the fru-enzymes were coinduced by fructose and coordinately repressed by succinate. Studies on the effect of succinate on differential rates of syntheses of the fru-enzymes revealed that their induced syntheses in fructose minimal medium were subject to transient as well as permanent (catabolite) repression by succinate. Succinate also caused a similar pattern of transient and permanent repression of the fructose transport system in A. brasilense. However, no inducer (fructose) exclusionlike effect was observed as there was no inhibition of fructose uptake in the presence of succinate with fructose-grown cells even when they were fully induced for succinate uptake activity.
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29
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Hertz R, Bar-Tana J. Reductive repression in Escherichia coli K-12 is mediated by oxygen radicals. Arch Biochem Biophys 1986; 250:54-62. [PMID: 3532957 DOI: 10.1016/0003-9861(86)90701-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Cyclic AMP (cAMP) content and the expression of cAMP-dependent phenotypes were positively correlated with respiration capacity in respiration-deficient mutants of Escherichia coli K-12 ("reductive repression," R. Hertz, and J. Bar-Tana, (1982) Arch. Biochem. Biophys. 213, 193-199). Reductive repression in respiration-deficient mutants could not be accounted for by respective changes in either the energy charge of adenine nucleotides or the redox state of pyridine nucleotides but could be ascribed to an increased formation of oxygen radicals under conditions of limited respiration. Scavengers of superoxide radicals eliminated reductive repression in respiration-deficient mutants with a concomitant increase in cAMP content. Such scavengers also effected a partial escape from permanent glucose catabolite repression, thus indicating a possible role played by oxygen radicals in both repression modes.
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30
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Ray NG, Vieth WR, Venkatasubramanian K. Active inducer transport and regulation of microbial enzyme biosynthesis in chemostat cultures. Ann N Y Acad Sci 1986; 469:212-29. [PMID: 3014976 DOI: 10.1111/j.1749-6632.1986.tb26499.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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31
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Wiame JM, Grenson M, Arst HN. Nitrogen catabolite repression in yeasts and filamentous fungi. Adv Microb Physiol 1985; 26:1-88. [PMID: 2869649 DOI: 10.1016/s0065-2911(08)60394-x] [Citation(s) in RCA: 244] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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32
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Abstract
The control of transcription initiation at the lactose operon promoter was investigated in vitro. We found that an upstream promoter (termed lac P2) interfered with RNA polymerase binding at the principal promoter (termed lac P1). The start site for lac P2 was located at base pair position -22 relative to the P1 start site. The addition of cAMP receptor protein and cAMP was shown to repress lac P2 and to activate lac P1. Abortive initiation reactions for both promoters were used to investigate the coordinate repression-activation elicited by CRP-cAMP. The effects of lac promoter mutations (L8, Ps, and UV5) were consistent with an important RNA polymerase positioning role for CRP-cAMP in the activation of lac operon expression.
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33
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Coleman G. The effect of glucose on the differential rates of extracellular protein and alpha-toxin formation by Staphylococcus aureus (Wood 46). Arch Microbiol 1983; 134:208-11. [PMID: 6615125 DOI: 10.1007/bf00407759] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The differential rates of formation of total extracellular protein and alpha-toxin by Staphylococcus aureus (Wood 46) were determined during aerobic growth, at 37 degrees C, in a complex medium containing 0.0, 0.25 or 1.0% (wt/vol) glucose. Different inocula were employed from 1% (vol/vol) of an overnight culture to 100% where bacterial cells were washed and resuspended in fresh medium without change in density. It was shown that under all conditions examined the differential rates of total extracellular protein formation exhibited a biphasic pattern characteristic of regulation based on 'competition'. This biphasic pattern was maintained even in the presence of a large inoculum and a high glucose concentration, conditions considered to favour the onset of catabolite repression. However, a lowering of the initial rate was observed with increasing glucose suggesting the superimposition of catabolite repression as a modulating effect under extreme conditions. In the case of the specific extracellular protein component, alpha-toxin, its differential rate of formation paralleled total exoprotein in all except the condition most favourable for catabolite accumulation when a deviation consistent with a pronounced catabolite repression of this component was demonstrated which was not pH-dependent.
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34
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Hertz R, Bar-Tana J. Modulation of the 3',5'-cyclic AMP content by the respiration rate in E. coli K-12. Arch Biochem Biophys 1982; 213:193-9. [PMID: 6277251 DOI: 10.1016/0003-9861(82)90455-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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35
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Zhu Y, Wu Y, Chen W, Tan C, Gao J, Fei J, Shih C. Induction and regulation of cellulase synthesis in Trichoderma pseudokoningii mutants EA3-867 and N2-78. Enzyme Microb Technol 1982. [DOI: 10.1016/0141-0229(82)90003-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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36
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Takahashi M, Blazy B, Baudras A. An equilibrium study of the cooperative binding of adenosine cyclic 3',5'-monophosphate and guanosine cyclic 3',5'-monophosphate to the adenosine cyclic 3',5'-monophosphate receptor protein from Escherichia coli. Biochemistry 1980; 19:5124-30. [PMID: 6257276 DOI: 10.1021/bi00563a029] [Citation(s) in RCA: 93] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The binding of adenosine cyclic 3',5'-monophosphate (cAMP) and guanosine cyclic 3',5'-monophosphate (cGMP) to the adenosine cyclic 3',5'-monophosphate receptor protein (CRP) from Escherichia coli was investigated by equilibrium dialysis at pH 8.0 and 20 degrees C at different ionic strengths (0.05--0.60 M). Both cAMP and cGMP bind to CRP with a negative cooperativity that is progressively changed to positive as the ionic strength is increased. The binding data were analyzed with an interactive model for two identical sites and site/site interactions with the interaction free energy--RT ln alpha, and the intrinsic binding constant K and cooperativity parameter alpha were computed. Double-label experiments showed that cGMP is strictly competitive with cAMP, and its binding parameters K and alpha are not very different from that for cAMP. Since two binding sites exist for each of the cyclic nucleotides in dimeric CRP and no change in the quaternary structure of the protein is observed on binding the ligands, it is proposed that the cooperativity originates in ligand/ligand interactions. When bound to double-stranded deoxyribonucleic acid (dsDNA), CRP binds cAMP more efficiently, and the cooperativity is positive even in conditions of low ionic strength where it is negative for the free protein. By contrast, cGMP binding properties remained unperturbed in dsDNA-bound CRP. Neither the intrinsic binding constant K nor the cooperativity parameter alpha was found to be very sensitive to changes of pH between 6.0 and 8.0 at 0.2 M ionic strength and 20 degrees C. For these conditions, the intrinsic free energy and entropy of binding of cAMP are delta H degree = -1.7 kcal . mol-1 and delta S degree = 15.6 eu, respectively.
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37
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38
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Blazy B, Takahashi M, Baudras A. Binding of CRP to DNA-dependent RNA polymerase from E. coli: modulation by cAMP of the interactions with free and DNA-bound holo and core enzyme. Mol Biol Rep 1980; 6:39-43. [PMID: 6248768 DOI: 10.1007/bf00775753] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The regulatory protein CRP (or CAP) from E. coli is shown to display two distinct patterns of binding interactions with DNA-dependent RNA polymerase. The free core enzyme, and both the core and the holo polymerase when bound to single-stranded DNA, can bind CRP in a cAMP-independent association reaction. Instead, the binding of CRP to free holoenzyme and to holo or core polymerase bound to native DNA was undetectable in the absence of cAMP. The specific ligand of CRP (cAMP) strengthens distinctively this class of interactions. In no case could any release of sigma-factor be demonstrated. Estimates of the dissociation constants were obtained for the various binding reactions which were investigated under quasi-physiological ionic conditions. These, together with the known values of the in vivo concentrations of CRP and RNA polymerase, suggest that the interactions described may have a functional significance.
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39
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Pavlasová E, Stejskalová E, Novotný C, Sikyta B. Effect of cyclic adenosine-3',5'-monophosphate on the simultaneous synthesis of beta-galactosidase and tryptophanase in Escherichia coli. Folia Microbiol (Praha) 1980; 25:16-23. [PMID: 6243599 DOI: 10.1007/bf02876393] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
When inducing simultaneously beta-galactosidase and tryptophanase in a batch culture either the synthesis of tryptophanase or of both enzymes is decreased due to an insufficient cAMP concentration. The addition of this nucleotide can overcome this decrease. In a continuous culture both enzymes are synthesized at the maximum rate, as the amount of cAMP produced during carbon limitation of growth is probably sufficient for the simultaneous synthesis of both enzymes. In the beta-galactosidase hyperproduction mutant cultivated continuously the level of beta-galactosidase markedly decreases when tryptophanase is simultaneously induced. Also this decrease is caused by cAMP insufficiency and can be overcome by increasing its concentration. cAMP is thus an important regulatory factor of both enzymes and becomes a limiting factor in their simultaneous synthesis; a competition for this regulatory compound apparently occurs and probably also a different mutual affinity of the regulatory complex with the promoter site of the enzyme operons is involved.
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Goldenbaum PE, Hall GA. Transport of cyclic adenosine 3',5'-monophosphate across Escherichia coli vesicle membranes. J Bacteriol 1979; 140:459-67. [PMID: 227841 PMCID: PMC216670 DOI: 10.1128/jb.140.2.459-467.1979] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The uptake and efflux of cyclic adenosine 3',5'-monophosphate (3',5'-cAMP) by Escherichia coli membrane vesicles were studied. Metabolic energy was not required for the uptake process and was found to actually decrease the amount of 3',5'-cAMP found in the vesicles. 3',5'-cAMP uptake exhibits saturation kinetics (Km = 10 mM, Vmax = 2.8 nmol/mg of protein per min) and was competitively inhibited by a number of 3',5'-cAMP analogs. The uptake of 3',5'-cAMP was found to be sharply affected by a membrane phase transition. The excretion of 3',5'-cAMP was studied by using everted membrane vesicles. Efflux in this system was dependent upon metabolic energy and was reduced or abolished by uncouplers. Different energy sources powered efflux at different rates, showing a relationship between the degree of membrane energization and rate of excretion of 3',5'-cAMP. The efflux process also displayed saturation kinetics (Km = 10.0 mM, Vmax = 0.98 nmol/mg of protein per min) and was competitively inhibited by the same 3',5'-cAMP analogs and to the same degree as was the uptake process. 3',5'-cAMP was found to be chemically unaltered by both the uptake and excretion processes. These data are interpreted as showing that the uptake and excretion of 3',5'-cAMP in E. coli membrane vesicles are carrier-mediated phenomena, possibly employing the same carrier system. Uptake is by facilitated diffusion whereas efflux is via an energy-dependent, active transport process. Evidence is presented showing that cells can regulate the number of 3',5'-cAMP transport carriers. The rate of 3',5'-cAMP excretion is possibly regulated by both the degree of membrane energization and the number of carriers present per cells.
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Yang JK, Bloom RW, Epstein W. Catabolite and transient repression in Escherichia coli do not require enzyme I of the phosphotransferase system. J Bacteriol 1979; 138:275-9. [PMID: 220212 PMCID: PMC218273 DOI: 10.1128/jb.138.1.275-279.1979] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Transient and catabolite repression with changes in intracellular concentrations of cyclic adenosine 3',5-monophosphate is produced by glycerol and by glucose-6-phosphate in a strain with a partial deletion of the structural gene for enzyme I of the phosphoenolpyruvate:sugar phosphotransferase system.
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Wanner BL, Kodaira R, Neidhardt FC. Regulation of lac operon expression: reappraisal of the theory of catabolite repression. J Bacteriol 1978; 136:947-54. [PMID: 214424 PMCID: PMC218529 DOI: 10.1128/jb.136.3.947-954.1978] [Citation(s) in RCA: 72] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The physiological state of Escherichia coli with respect to (permanent) catabolite repression was assessed by measuring the steady-state level of beta-galactosidase in induced or in constitutive cells under a variety of growth conditions. Four results were obtained. (i) Catabolite repression had a major effect on fully induced or constitutive expression of the lac gene, and the magnitude of this effect was found to be dependent on the promoter structure; cells with a wild-type lac promoter showed an 18-fold variation in lac expression, and cells with the lacP37 (formerly lac-L37) promoter exhibited several hundred-fold variation. (ii) Exogenous adenosine cyclic 3',5'-monophosphoric acid (cAMP) could not abolish catabolite repression, even though several controls demonstrated that cAMP was entering the cells in significant amounts. (Rapid intracellular degradation of cAMP could not be ruled out.) (iii) Neither the growth rate nor the presence of biosynthetic products altered the degree of catabolite repression; all variation could be related to the catabolites present in the growth medium. (iv) Slowing by imposing an amino acid restriction decreased the differential rate of beta-galactosidase synthesis from the wild-type lac promoter when bacteria were cultured in either the absence or presence of cAMP; this decreased lac expression also occurred when the bacteria harbored the catabolite-insensitive lacP5 (formerly lacUV5) promoter mutation. These findings support the idea that (permanent) catabolite repression is set by the catabolites in the growth medium and may not be related to an imbalance between catabolism and anabolism.
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Hamilton IR, Lo GC. Co-induction of beta-galactosidase and the lactose-P-enolpyruvate phosphotransferase system in Streptococcus salivarius and Streptococcus mutans. J Bacteriol 1978; 136:900-8. [PMID: 214423 PMCID: PMC218523 DOI: 10.1128/jb.136.3.900-908.1978] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The addition of lactose, galactose, or isopropyl-beta-D-thiogalactoside (IPTG) to glucose-grown cells of Streptococcus salivarius 25975 resulted in the co-induction of both the lactose-P-enolpyruvate phosphotransferase system (lactose-PTS) and beta-galactosidase, with the latter the predominant metabolic system. With various strains of Streptococcus mutans and Streptococcus sanguis 10556, on the other hand, the lactose-PTS was the major metabolic pathway with beta-galactosidase induced either to low or negligible levels. In all cases, induction of the lactose-PTS resulted in the concomitant induction of 6-P-beta-galactosidase. The induction by lactose of both the lactose-PTS and beta-galactosidase in all strains was repressed by glucose and other catabolites, notably, fructose. Induction of beta-galactosidase in S. salivarius 25975 by IPTG was, however, relatively resistant to glucose repression. Induction experiments with IPTG and lactose suggested that a cellular metabolite of lactose metabolism was a repressor of enzyme activity. Exogenous cAMP was shown to reverse the transient repression by glucose of beta-galactosidase induction in cells of S. salivarius 25975 receiving lactose, provided the cells were grown with small amounts of toluene to overcome the permeability barrier to this nucleotide, cAMP, was however, unable to overcome the permanent repression of beta-galactosidase activity to a significant extent under these conditions.
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Näslund M, Ehrenberg L. Suppression of induced beta-galactosidase synthesis by cysteamine and its reversion by gamma-irradiation in the presence of ascorbate. INTERNATIONAL JOURNAL OF RADIATION BIOLOGY AND RELATED STUDIES IN PHYSICS, CHEMISTRY, AND MEDICINE 1978; 34:411-5. [PMID: 224000 DOI: 10.1080/09553007814551071] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The induced synthesis of beta-galactosidase in E. coli was found to be inhibited by cysteamine. This inhibitory effect of the SH compound was antagonized by the addition of ascorbate followed by gamma-irradiation with relatively low doses. The cAMP level which, it has been suggested, plays a role in the radioprotective action of cysteamine, is stabilized by ascorbate against changes induced by irradiation.
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O'Farrell P, Polisky B, Gelfand DH. Regulated expression by readthrough translation from a plasmid-encoded beta-galactosidase. J Bacteriol 1978; 134:645-54. [PMID: 207672 PMCID: PMC222298 DOI: 10.1128/jb.134.2.645-654.1978] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
We have characterized expression of beta-galactosidase from a plasmid cloning vehicle, pBGP120, which carries most of the lacZ gene and contains a single EcoRI site near the end of lacZ. In addition, we have examined expression of heterologous DNA inserted at the position of the EcoRI site. The EcoRI site was shown to be within the sequence coding for beta-galactosidase and its precise location and phase were deduced. Insertion of heterologous EcoRI-generated DNA fragments altered the molecular weight of the plasmid-encoded beta-galactosidase polypeptide. Those insertions that were in the correct phase were expressed at a high level as a fused protein. The different forms of beta-galactosidase polypeptides produced by various hybrid plasmids were all stable proteins. The level of expression of the plasmid-encoded beta-galactosidase was several times higher than maximal expression of chromosome-encoded beta-galactosidase, suggesting that expression is proportional to gene copy number. The expression of the plasmid lacZ gene was controlled by cyclic AMP. When grown in a cya strain (DG74), expression was dependent on exogenous cyclic AMP. Although in normal strains there was insufficient lac repressor to inactivate all copies of the plasmid, repressor regulation was restored when the plasmid was grown in a strain (M96) that overproduces the lac repressor.
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Wainwright M, Beacham IR. The effect of translation and transcription inhibitors on the synthesis of periplasmic phosphatases in E. coli. MOLECULAR & GENERAL GENETICS : MGG 1977; 154:67-73. [PMID: 142903 DOI: 10.1007/bf00265578] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Previous studies by others have indicated that the synthesis of secreted enzymes is unusually sensitive to many translation inhibitors and resistant, for about 30 min, to rifampicin. We have studied the sensitivity of secreted (periplasmic) phosphatases to such inhibitors. Alkaline phosphatase synthesis is more sensitive than total protein synthesis to tetracyclin and spectinomycin, but not to sparsomycin, streptomycin, chloramphenicol, kasugamycin, blasticidin S or thiostrepton; it is slightly more resistant than total protein synthesis to the latter two antibiotics. Acid hexose-phosphatase was also preferentially sensitive to tetracyclin and spectinomycin and also to kasugamycin. beta-galactosidase was also included in the study, as an intracellular enzyme, and was found to be preferentially inhibited ("repressed"), sometimes transiently, by all eight translation inhibitors. This effect did not seem to be mediated through cyclic AMP or guanosine tetraphosphate; the "repression" was still evident in mutants with altered rho factor indicating that it may also not be related to artificial polarity. Synthesis of both periplasmic phosphatases was immediately inhibited by rifampicin. These results differ from those found in previous studies with other organisms and suggest a reappraisal of the usual interpretation of these phenomena.
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Fiil NP, Willumsen BM, Friesen JD, von Meyenburg K. Interaction of alleles of the relA, relC and spoT genes in Escherichia coli: analysis of the interconversion of GTP, ppGpp and pppGpp. MOLECULAR & GENERAL GENETICS : MGG 1977; 150:87-101. [PMID: 319345 DOI: 10.1007/bf02425329] [Citation(s) in RCA: 94] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Mutants in the spo T gene have been isolated as stringent second site revertants of the relC mutation. These show varying degrees of the characteristics associated with the spoT1 gene, viz relative amount and absolute levels of both pppGpp and ppGpp and the decay rate of the latter. The entry of 3H-guanosine into GTP and ppGpr pools in spoT+ and spoT1 cells either growing exponentially or during amino acid starvation was determined, and the rate of ppGpp synthesis and its decay constant calculated. During exponential growth the ppGpp pool is 2-fold higher, its decay constant 10-fold lower, and its synthesis rate 5-fold lower in spoT- than in spoT+ cells; during amino acid starvation the ppGpp pool is 2-fold higher, its decay constant 20-fold lower, and its synthesis rate 10-fold lower in spoT than in spoT+ cells. In one of the "intermediate" spoT mutants the rate of entry of 3H-guanosine into GTP, ppGpp and pppGpp was measured during amino acid starvation. The data form the basis of a model for the interconversion of the guanosine nucleotides in which the flow is: GDP leads to GTP leads to pppGpp leads to ppGpp leads to Y. Calculations of the rates of synthesis and conversion of pppGpp and ppGpp under various conditions in various spoT+ and spoT- strains indicate that the ppGpp concentration indirectly controls the rate of pppGpp synthesis.
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Bass R, Heffernan L, Sweadner K, Englesberg E. The site for catabolite deactivation in the L-arabinose BAD operon in Escherichia coli B/r. Arch Microbiol 1976; 110:135-43. [PMID: 189718 DOI: 10.1007/bf00416978] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A series of deletions beginning in the leu operon and continuing into the araC gene and also into the ara controlling site region were analyzed in reciprocal merodiploids, e.g., F' A2Cc67/B24delta719, F' B24delta719/A2Cc67, for their effects on catabolite deactivation (CD). The results of these experiments are consistent with placing the catabolite gene activator-cyclic AMP sensitive site in the controlling site region between araB and araO. With a deletion mutant, delta1109, that places araBAD under leu control when transcription begins at leuP, the araBAD operon is immune to CD even though araCGA, araP and araI are intact and functional. To focus attention on the fine structure and related functions of this region we propose that the three proteins that function therein have separate sites of action: araI (initiator-site for activator), araP (promoter-site for RNA polymerase) and ara(CGA) (catabolite gene activator-site for CGA-cAMP). None of the eighteen initiator constitutive mutants (Ic) tested have any significant effect on catabolite derepression or on the maximal level of expression of the operon supporting the view that the araI site may be distinct from araP and ARA(CGA). A series of constitutive mutants in the araC gene (Cc) also have no pronounced effect on catabolite deactivation.
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