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Improvement of Lignocellulolytic Enzyme Production Mediated by Calcium Signaling in Bacillus subtilis Z2 under Graphene Oxide Stress. Appl Environ Microbiol 2022; 88:e0096022. [PMID: 36121214 PMCID: PMC9552604 DOI: 10.1128/aem.00960-22] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An increase in exoenzyme production can be enhanced by environmental stresses such as graphene oxide (GO) stress, but the link between the two events is still unclear. In this work, the effect of GO as an environmental stress factor on exoenzyme (lignocellulolytic enzyme, amylase, peptidase, and protease) biosynthesis was investigated in Bacillus subtilis Z2, and a plausible mechanism by which cytosolic Ca2+ regulates lignocellulolytic enzyme production in B. subtilis Z2 subjected to GO stress was proposed. The filter paper-hydrolyzing (FPase [representing total cellulase]), carboxymethylcellulase (CMCase [representing endoglucanase]), and β-glucosidase activities and extracellular protein concentration of the wild-type strain under 10 μg/mL GO stress were 1.37-, 1.64-, 1.24-, and 1.16-fold those of the control (without GO stress), respectively. Correspondingly, the transcription levels of lignocellulolytic enzyme genes, cytosolic Ca2+ level, and biomass concentration of B. subtilis were all increased. With lignocellulolytic enzyme from B. subtilis used to hydrolyze alkali-pretreated rice straw, the released reducing sugar concentration reached 265.53 mg/g, and the removal rates of cellulose, hemicellulose, and lignin were 52.4%, 30.1%, and 7.5%, respectively. Furthermore, transcriptome data revealed that intracellular Ca2+ homeostasis played a key role in regulating the levels of gene transcription related to the synthesis of lignocellulolytic enzymes and exoenzymes. Finally, the use of Ca2+ inhibitors (LaCl3 and EDTA) and deletion of spcF (a calmodulin-like protein gene) further demonstrated that the overexpression of those genes was regulated via calcium signaling in B. subtilis subjected to GO stress. IMPORTANCE To effectively convert lignocellulose into fermentable sugars, high lignocellulolytic enzyme loading is needed. Graphene oxide (GO) has been shown to promote exoenzyme (lignocellulolytic enzyme, amylase, peptidase, and protease) production in some microorganisms; however, the regulatory mechanism of the biosynthesis of lignocellulolytic enzymes under GO stress remains unclear. In this work, the lignocellulolytic enzyme production of B. subtilis under GO stress was investigated, and the potential mechanism by which B. subtilis enhanced lignocellulolytic enzyme production through the calcium signaling pathway under GO stress was proposed. This work revealed the role of calcium signaling in the production of enzymes under external environmental stress and provided a direction to facilitate lignocellulolytic enzyme production by B. subtilis.
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Trabalza S, Buonaurio R, Del Pino AM, Palmerini CA, van den Burg HA, Moretti C. A Spectrofluorophotometrical Method Based on Fura-2-AM Probe to Determine Cytosolic Ca 2+ Level in Pseudomonas syringae Complex Bacterial Cells. Bio Protoc 2021; 11:e3949. [PMID: 33855111 DOI: 10.21769/bioprotoc.3949] [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: 09/23/2020] [Revised: 01/13/2021] [Accepted: 01/14/2021] [Indexed: 11/02/2022] Open
Abstract
Calcium signaling is an emerging mechanism by which bacteria respond to environmental cues. To measure the intracellular free-calcium concentration in bacterial cells, [Ca2+]i, a simple spectrofluorometric method based on the chemical probe Fura 2-acetoxy methyl ester (Fura 2-AM) is here presented using Pseudomonad bacterial cells. This is an alternative and quantitative method that can be completed in a short period of time with low costs, and it does not require the induction of heterologously expressed protein-based probes like Aequorin. Furthermore, it is possible to verify the properties of membrane channels involved in Ca2+ entry from the extracellular matrix. This method is in particular valuable for measuring [Ca2+]i in the range of 0.1-39.8 µM in small cells like those of prokaryotes.
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Affiliation(s)
- Simone Trabalza
- Department of Agricultural, Food and Environmental Science, University of Perugia, Perugia, Italy.,Molecular Plant Pathology, Swammerdam Institute for Life Sciences (SILS), University of Amsterdam, Amsterdam, the Netherlands
| | - Roberto Buonaurio
- Department of Agricultural, Food and Environmental Science, University of Perugia, Perugia, Italy
| | - Alberto M Del Pino
- Department of Agricultural, Food and Environmental Science, University of Perugia, Perugia, Italy
| | - Carlo A Palmerini
- Department of Agricultural, Food and Environmental Science, University of Perugia, Perugia, Italy
| | - Harrold A van den Burg
- Molecular Plant Pathology, Swammerdam Institute for Life Sciences (SILS), University of Amsterdam, Amsterdam, the Netherlands
| | - Chiaraluce Moretti
- Department of Agricultural, Food and Environmental Science, University of Perugia, Perugia, Italy
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Kingston AW, Ponkratz C, Raleigh EA. Rpn (YhgA-Like) Proteins of Escherichia coli K-12 and Their Contribution to RecA-Independent Horizontal Transfer. J Bacteriol 2017; 199:e00787-16. [PMID: 28096446 PMCID: PMC5350276 DOI: 10.1128/jb.00787-16] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 01/09/2017] [Indexed: 01/21/2023] Open
Abstract
Bacteria use a variety of DNA-mobilizing enzymes to facilitate environmental niche adaptation via horizontal gene transfer. This has led to real-world problems, like the spread of antibiotic resistance, yet many mobilization proteins remain undefined. In the study described here, we investigated the uncharacterized family of YhgA-like transposase_31 (Pfam PF04754) proteins. Our primary focus was the genetic and biochemical properties of the five Escherichia coli K-12 members of this family, which we designate RpnA to RpnE, where Rpn represents recombination-promoting nuclease. We employed a conjugal system developed by our lab that demanded RecA-independent recombination following transfer of chromosomal DNA. Overexpression of RpnA (YhgA), RpnB (YfcI), RpnC (YadD), and RpnD (YjiP) increased RecA-independent recombination, reduced cell viability, and induced the expression of reporter of DNA damage. For the exemplar of the family, RpnA, mutational changes in proposed catalytic residues reduced or abolished all three phenotypes in concert. In vitro, RpnA displayed magnesium-dependent, calcium-stimulated DNA endonuclease activity with little, if any, sequence specificity and a preference for double-strand cleavage. We propose that Rpn/YhgA-like family nucleases can participate in gene acquisition processes.IMPORTANCE Bacteria adapt to new environments by obtaining new genes from other bacteria. Here, we characterize a set of genes that can promote the acquisition process by a novel mechanism. Genome comparisons had suggested the horizontal spread of the genes for the YhgA-like family of proteins through bacteria. Although annotated as transposase_31, no member of the family has previously been characterized experimentally. We show that four Escherichia coli K-12 paralogs contribute to a novel RecA-independent recombination mechanism in vivo For RpnA, we demonstrate in vitro action as a magnesium-dependent, calcium-stimulated nonspecific DNA endonuclease. The cleavage products are capable of providing priming sites for DNA polymerase, which can enable DNA joining by primer-template switching.
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Kosmachevskaya OV, Shumaev KB, Topunov AF. Carbonyl Stress in Bacteria: Causes and Consequences. BIOCHEMISTRY (MOSCOW) 2016; 80:1655-71. [PMID: 26878572 DOI: 10.1134/s0006297915130039] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Pathways of synthesis of the α-reactive carbonyl compound methylglyoxal (MG) in prokaryotes are described in this review. Accumulation of MG leads to development of carbonyl stress. Some pathways of MG formation are similar for both pro- and eukaryotes, but there are reactions specific for prokaryotes, e.g. the methylglyoxal synthase reaction. This reaction and the glyoxalase system constitute an alternative pathway of glucose catabolism - the MG shunt not associated with the synthesis of ATP. In violation of the regulation of metabolism, the cell uses MG shunt as well as other glycolysis shunting pathways and futile cycles enabling stabilization of its energetic status. MG was first examined as a biologically active metabolic factor participating in the formation of phenotypic polymorphism and hyperpersistent potential of bacterial populations. The study of carbonyl stress is interesting for evolutionary biology and can be useful for constructing highly effective producer strains.
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Affiliation(s)
- O V Kosmachevskaya
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow, 119071, Russia.
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Guragain M, Campbell A, Patrauchan M. Measurement of Intracellular Calcium Concentration in Pseudomonas aeruginosa. Bio Protoc 2016. [DOI: 10.21769/bioprotoc.2041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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Catania C, Ajo-Franklin C, Bazan GC. Membrane permeabilization by conjugated oligoelectrolytes accelerates whole-cell catalysis. RSC Adv 2016. [DOI: 10.1039/c6ra23083k] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Conjugated oligoelectrolytes (COE) increase outer membrane permeability inEscherichia coli,improve transport of small molecules through the cell envelope and thus accelerate whole-cell catalysis.
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Affiliation(s)
- Chelsea Catania
- Materials Department
- University of California
- Santa Barbara 93106
- USA
| | - Caroline M. Ajo-Franklin
- Physical Biosciences Division
- Materials Science Division and Synthetic Biology Institute
- Lawrence Berkeley National Laboratory
- Berkeley
- USA
| | - Guillermo C. Bazan
- Center for Polymers and Organic Solids
- Department of Chemistry and Biochemistry
- University of California
- Santa Barbara 93106
- USA
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Calcium binding proteins and calcium signaling in prokaryotes. Cell Calcium 2014; 57:151-65. [PMID: 25555683 DOI: 10.1016/j.ceca.2014.12.006] [Citation(s) in RCA: 136] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 12/08/2014] [Accepted: 12/09/2014] [Indexed: 11/20/2022]
Abstract
With the continued increase of genomic information and computational analyses during the recent years, the number of newly discovered calcium binding proteins (CaBPs) in prokaryotic organisms has increased dramatically. These proteins contain sequences that closely resemble a variety of eukaryotic calcium (Ca(2+)) binding motifs including the canonical and pseudo EF-hand motifs, Ca(2+)-binding β-roll, Greek key motif and a novel putative Ca(2+)-binding domain, called the Big domain. Prokaryotic CaBPs have been implicated in diverse cellular activities such as division, development, motility, homeostasis, stress response, secretion, transport, signaling and host-pathogen interactions. However, the majority of these proteins are hypothetical, and only few of them have been studied functionally. The finding of many diverse CaBPs in prokaryotic genomes opens an exciting area of research to explore and define the role of Ca(2+) in organisms other than eukaryotes. This review presents the most recent developments in the field of CaBPs and novel advancements in the role of Ca(2+) in prokaryotes.
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Liu S, Zhang Z, Ni J. Effects of Ca2+ on activity restoration of the damaged anammox consortium. BIORESOURCE TECHNOLOGY 2013; 143:315-321. [PMID: 23811064 DOI: 10.1016/j.biortech.2013.06.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 06/01/2013] [Accepted: 06/03/2013] [Indexed: 06/02/2023]
Abstract
Intracellular free Ca(2+) are canonically well known as significant "second messenger" in cells and regarded as critical regulators of bacterial metabolism. We investigated the influence of Ca(2+) dosage on the restoration of anammox consortium, in which nearly 80% cells were dead or badly damaged. Chemical analysis and flow cytometry (FCM) demonstrated that Ca(2+) dosage was of primary importance and the restoration process was apparently faster with increasing Ca(2+) as its concentration was ranged 0.02-0.5mM in feeding. Using FCM and Fura red fluorescence labeling for analysis of intracellular free Ca(2+), we found a strong correlation between external Ca(2+) concentration in feeding and the levels of steady-state intracellular free Ca(2+), the abundance of which was considered as the intrinsic causes for favoring anammox consortium restoration. This study provides new insight into the ions effects on rapid restoration of damaged anammox consortium, targeting efficient nitrogen removal from wastewater with anammox process.
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Affiliation(s)
- Sitong Liu
- Department of Environmental Engineering, Peking University, Beijing 100871, PR China.
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Liu L, Yang H, Shin HD, Chen RR, Li J, Du G, Chen J. How to achieve high-level expression of microbial enzymes: strategies and perspectives. Bioengineered 2013; 4:212-23. [PMID: 23686280 DOI: 10.4161/bioe.24761] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Microbial enzymes have been used in a large number of fields, such as chemical, agricultural and biopharmaceutical industries. The enzyme production rate and yield are the main factors to consider when choosing the appropriate expression system for the production of recombinant proteins. Recombinant enzymes have been expressed in bacteria (e.g., Escherichia coli, Bacillus and lactic acid bacteria), filamentous fungi (e.g., Aspergillus) and yeasts (e.g., Pichia pastoris). The favorable and very advantageous characteristics of these species have resulted in an increasing number of biotechnological applications. Bacterial hosts (e.g., E. coli) can be used to quickly and easily overexpress recombinant enzymes; however, bacterial systems cannot express very large proteins and proteins that require post-translational modifications. The main bacterial expression hosts, with the exception of lactic acid bacteria and filamentous fungi, can produce several toxins which are not compatible with the expression of recombinant enzymes in food and drugs. However, due to the multiplicity of the physiological impacts arising from high-level expression of genes encoding the enzymes and expression hosts, the goal of overproduction can hardly be achieved, and therefore, the yield of recombinant enzymes is limited. In this review, the recent strategies used for the high-level expression of microbial enzymes in the hosts mentioned above are summarized and the prospects are also discussed. We hope this review will contribute to the development of the enzyme-related research field.
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Affiliation(s)
- Long Liu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, China
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Combination of site-directed mutagenesis and calcium ion addition for enhanced production of thermostable MBP-fused heparinase I in recombinant Escherichia coli. Appl Microbiol Biotechnol 2012; 97:2907-16. [PMID: 22588503 DOI: 10.1007/s00253-012-4145-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 04/13/2012] [Accepted: 04/26/2012] [Indexed: 10/28/2022]
Abstract
Heparinase I (HepI), which specifically cleaves heparin and heparan sulfate, is one of the most extensively studied glycosaminoglycan lyases. Low productivity of HepI has largely hindered its industrial and pharmaceutical applications. Loss of bacterial HepI enzyme activity through poor thermostability during its expression and purification process in production can be an important issue. In this study, using a thermostabilization strategy combining site-directed mutagenesis and calcium ion addition during its production markedly improved the yield of maltose-binding protein-fused HepI (MBP-HepI) from recombinant Escherichia coli. Substitution of Cys297 to serine in MBP-HepI offered a 30.6% increase in the recovered total enzyme activity due to a mutation-induced thermostabilizing effect. Furthermore, upon addition of Ca2+ as a stabilizer at optimized concentrations throughout its expression, extraction, and purification process, purified mutant MBP-HepI showed a specific activity of 56.3 IU/mg, 206% higher than that of the wild type obtained without Ca2+ addition, along with a 177% increase in the recovered total enzyme activity. The enzyme obtained through this novel approach also exhibited significantly enhanced thermostability, as indicated by both experimental data and the kinetic modeling. High-yield production of thermostable MBP-HepI using the present system will facilitate its applications in laboratory-scale heparin analysis as well as industrial-scale production of low molecular weight heparin as an improved anticoagulant substitute.
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Ryanodine receptor calcium release channels: an evolutionary perspective. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:159-82. [PMID: 22453942 DOI: 10.1007/978-94-007-2888-2_7] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Ryanodine receptors (RyRs), along with the related inositol 1,4,5-trisphosphate receptors (IP(3)Rs), mediate the release of Ca(2+) from intracellular organelles of eukaryotes. As discussed in other chapters, such increases in intracellular Ca(2+) levels act a fundamental second messenger, regulating a diverse array of cellular processes. For over two decades, it has been reported that vertebrates express multiple RYR genes, whereas non-vertebrate multicellular organisms possess a single homologue within their genomes. Recently, the existence of RyR-like channels in unicellular organisms has also been reported. This chapter exploits recent expansions in available genome data to generate an overview of the expression of RyR-like genes in organisms representing a broad range of viral, archaeal, bacterial and eukaryotic taxa. Analyses of the multidomain structures and phylogenetic relationships of these proteins has lead to a model in which, early during eukaryotic evolution, IP(3)R-like ancestral Ca(2+) release channels were converted to RyR proteins via the addition of promiscuous protein domains, possibly via horizontal gene transfer mechanisms.
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Campbell AK, Matthews SB, Vassel N, Cox CD, Naseem R, Chaichi J, Holland IB, Green J, Wann KT. Bacterial metabolic 'toxins': a new mechanism for lactose and food intolerance, and irritable bowel syndrome. Toxicology 2010; 278:268-76. [PMID: 20851732 DOI: 10.1016/j.tox.2010.09.001] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Revised: 08/18/2010] [Accepted: 09/05/2010] [Indexed: 10/19/2022]
Abstract
Lactose and food intolerance cause a wide range of gut and systemic symptoms, including gas, gut pain, diarrhoea or constipation, severe headaches, severe fatigue, loss of cognitive functions such as concentration, memory and reasoning, muscle and joint pain, heart palpitations, and a variety of allergies (Matthews and Campbell, 2000; Matthews et al., 2005; Waud et al., 2008). These can be explained by the production of toxic metabolites from gut bacteria, as a result of anaerobic digestion of carbohydrates and other foods, not absorbed in the small intestine. These metabolites include alcohols, diols such as butan 2,3 diol, ketones, acids, and aldehydes such as methylglyoxal (Campbell et al., 2005, 2009). These 'toxins' induce calcium signals in bacteria and affect their growth, thereby acting to modify the balance of microflora in the gut (Campbell et al., 2004, 2007a,b). These bacterial 'toxins' also affect signalling mechanisms in cells around the body, thereby explaining the wide range of symptoms in people with food intolerance. This new mechanism also explains the most common referral to gastroenterologists, irritable bowel syndrome (IBS), and the illness that afflicted Charles Darwin for 50 years (Campbell and Matthews, 2005a,b). We propose it will lead to a new understanding of the molecular mechanism of type 2 diabetes and some cancers.
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Affiliation(s)
- A K Campbell
- Welsh School of Pharmacy, Cardiff University, King Edward VII Avenue, Cardiff CF103NB, UK.
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Downing BPB, Rutenberg AD, Touhami A, Jericho M. Subcellular Min oscillations as a single-cell reporter of the action of polycations, protamine, and gentamicin on Escherichia coli. PLoS One 2009; 4:e7285. [PMID: 19789705 PMCID: PMC2749335 DOI: 10.1371/journal.pone.0007285] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2009] [Accepted: 06/29/2009] [Indexed: 11/19/2022] Open
Abstract
Background In Escherichia coli, MinD-GFP fusion proteins show rapid pole to pole oscillations. The objective was to investigate the effects of extracellular cations on the subcellular oscillation of cytoplasmic MinD within Escherichia coli. Methodology/Principal Findings We exposed bacteria to the extracellular cations Ca++, Mg++, the cationic antimicrobial peptide (CAP) protamine, and the cationic aminoglycoside gentamicin. We found rapid and substantial increases in the average MinD oscillation periods in the presence of any of these polyvalent cations. For Ca++ and Mg++ the increases in period were transient, even with a constant extracellular concentration, while increases in period for protamine or gentamicin were apparently irreversible. We also found striking interdependence in the action of the small cations with protamine or gentamicin, distorted oscillations under the action of intermediate levels of gentamicin and Ca++, and reversible freezing of the Min oscillation at high cationic concentrations. Conclusions/Significance Intracellular Min oscillations provide a fast single-cell reporter of bacterial response to extracellular polycations, which can be explained by the penetration of polycations into cells.
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Affiliation(s)
- Benjamin P. B. Downing
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Andrew D. Rutenberg
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Ahmed Touhami
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Manfred Jericho
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada
- * E-mail:
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ATP regulates calcium efflux and growth in E. coli. J Mol Biol 2009; 391:42-56. [PMID: 19481094 DOI: 10.1016/j.jmb.2009.05.064] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2009] [Revised: 05/11/2009] [Accepted: 05/20/2009] [Indexed: 11/21/2022]
Abstract
Escherichia coli regulates cytosolic free Ca(2+) in the micromolar range through influx and efflux. Herein, we show for the first time that ATP is essential for Ca(2+) efflux and that ATP levels also affect generation time. A transcriptome analysis identified 110 genes whose expression responded to an increase in cytosolic Ca(2+) (41 elevated, 69 depressed). Of these, 3 transport proteins and 4 membrane proteins were identified as potential Ca(2+) transport pathways. Expression of a further 943 genes was modified after 1 h in growth medium containing Ca(2+) relative to time zero. Based on the microarray results and other predicted possible Ca(2+) transporters, the level of cytosolic free Ca(2+) was measured in selected mutants from the Keio knockout collection using intracellular aequorin. In this way, we identified a knockout of atpD, coding for a component of the F(o)F(1) ATPase, as defective in Ca(2+) efflux. Seven other putative Ca(2+) transport proteins exhibited normal Ca(2+) handling. The defect in the DeltaatpD knockout cells could be explained by a 70% reduction in ATP. One millimolar glucose or 1 mM methylglyoxal raised ATP in the DeltaatpD knockout cells to that of the wild type and restored Ca(2+) efflux. One millimolar 2,4-dinitrophenol lowered the ATP in wild type to that in the DeltaatpD cells. Under these conditions, a similar defect in Ca(2+) efflux in wild type was observed in DeltaatpD cells. Ten millimolar concentration of Ca(2+) resulted in a 30% elevation in ATP in wild type and was accompanied by a 10% reduction in generation time under these conditions. Knockouts of pitB, a potential Ca(2+) transporter, atoA, the beta subunit of acetate CoA-transferase likely to be involved in polyhydroxybutyrate synthesis, and ppk, encoding polyphosphate kinase, all indicated no defect in Ca(2+) efflux. We therefore propose that ATP is most likely to regulate Ca(2+) efflux in E. coli through an ATPase.
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The vibrio cholerae hybrid sensor kinase VieS contributes to motility and biofilm regulation by altering the cyclic diguanylate level. J Bacteriol 2008; 190:6439-47. [PMID: 18676667 DOI: 10.1128/jb.00541-08] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Phosphorelay systems are important mediators of signal transduction during bacterial adaptation to new environments. Previously we described the vieSAB operon, encoding a putative three-protein component phosphorelay involved in regulating Vibrio cholerae virulence gene expression. At least part of the regulatory activity of VieSAB is exerted through the cyclic diguanylate (c-di-GMP)-degrading activity of the putative response regulator VieA. So far no direct evidence that VieSAB encodes a phosphorelay system exists. In addition, the role VieS plays in modulating VieA activity remains unclear. To address these questions, we expressed and purified VieA and a soluble cytoplasmic portion of VieS and used them in autophosphorylation and phosphotransfer assays. These assays showed that VieS has kinase activity in vitro and is able to selectively phosphorylate VieA. A phenotypic comparison revealed that deletion of vieS results in increased biofilm production comparable to that seen for deletion of vieA, whereas motility was decreased only slightly in the DeltavieS mutant compared to the profound defect observed in a DeltavieA mutant. We also found that the DeltavieS strain has a lower level of vieA transcript and, similar to a DeltavieA mutant, an increased intracellular level of c-di-GMP. Further analysis using site-directed vieA mutants showed that some of the phenotypes observed were due to the phosphorylation status of VieA. The evidence presented in this report is the first to link VieS and VieA biochemically and genetically, lending support to the hypothesis that these proteins function together in a signaling system.
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Campbell AK, Naseem R, Holland IB, Matthews SB, Wann KT. Methylglyoxal and other carbohydrate metabolites induce lanthanum-sensitive Ca2+ transients and inhibit growth in E. coli. Arch Biochem Biophys 2007; 468:107-13. [DOI: 10.1016/j.abb.2007.09.006] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2007] [Revised: 09/07/2007] [Accepted: 09/09/2007] [Indexed: 01/10/2023]
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