1
|
Norris V, Kayser C, Muskhelishvili G, Konto-Ghiorghi Y. The roles of nucleoid-associated proteins and topoisomerases in chromosome structure, strand segregation, and the generation of phenotypic heterogeneity in bacteria. FEMS Microbiol Rev 2023; 47:fuac049. [PMID: 36549664 DOI: 10.1093/femsre/fuac049] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 12/06/2022] [Accepted: 12/21/2022] [Indexed: 12/24/2022] Open
Abstract
How to adapt to a changing environment is a fundamental, recurrent problem confronting cells. One solution is for cells to organize their constituents into a limited number of spatially extended, functionally relevant, macromolecular assemblies or hyperstructures, and then to segregate these hyperstructures asymmetrically into daughter cells. This asymmetric segregation becomes a particularly powerful way of generating a coherent phenotypic diversity when the segregation of certain hyperstructures is with only one of the parental DNA strands and when this pattern of segregation continues over successive generations. Candidate hyperstructures for such asymmetric segregation in prokaryotes include those containing the nucleoid-associated proteins (NAPs) and the topoisomerases. Another solution to the problem of creating a coherent phenotypic diversity is by creating a growth-environment-dependent gradient of supercoiling generated along the replication origin-to-terminus axis of the bacterial chromosome. This gradient is modulated by transcription, NAPs, and topoisomerases. Here, we focus primarily on two topoisomerases, TopoIV and DNA gyrase in Escherichia coli, on three of its NAPs (H-NS, HU, and IHF), and on the single-stranded binding protein, SSB. We propose that the combination of supercoiling-gradient-dependent and strand-segregation-dependent topoisomerase activities result in significant differences in the supercoiling of daughter chromosomes, and hence in the phenotypes of daughter cells.
Collapse
Affiliation(s)
- Vic Norris
- University of Rouen, Laboratory of Bacterial Communication and Anti-infection Strategies, EA 4312, 76821 Mont Saint Aignan, France
| | - Clara Kayser
- University of Rouen, Laboratory of Bacterial Communication and Anti-infection Strategies, EA 4312, 76821 Mont Saint Aignan, France
| | - Georgi Muskhelishvili
- Agricultural University of Georgia, School of Natural Sciences, 0159 Tbilisi, Georgia
| | - Yoan Konto-Ghiorghi
- University of Rouen, Laboratory of Bacterial Communication and Anti-infection Strategies, EA 4312, 76821 Mont Saint Aignan, France
| |
Collapse
|
2
|
Kohiyama M, Herrick J, Norris V. Open Questions about the Roles of DnaA, Related Proteins, and Hyperstructure Dynamics in the Cell Cycle. Life (Basel) 2023; 13:1890. [PMID: 37763294 PMCID: PMC10532879 DOI: 10.3390/life13091890] [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: 07/18/2023] [Revised: 08/29/2023] [Accepted: 09/06/2023] [Indexed: 09/29/2023] Open
Abstract
The DnaA protein has long been considered to play the key role in the initiation of chromosome replication in modern bacteria. Many questions about this role, however, remain unanswered. Here, we raise these questions within a framework based on the dynamics of hyperstructures, alias large assemblies of molecules and macromolecules that perform a function. In these dynamics, hyperstructures can (1) emit and receive signals or (2) fuse and separate from one another. We ask whether the DnaA-based initiation hyperstructure acts as a logic gate receiving information from the membrane, the chromosome, and metabolism to trigger replication; we try to phrase some of these questions in terms of DNA supercoiling, strand opening, glycolytic enzymes, SeqA, ribonucleotide reductase, the macromolecular synthesis operon, post-translational modifications, and metabolic pools. Finally, we ask whether, underpinning the regulation of the cell cycle, there is a physico-chemical clock inherited from the first protocells, and whether this clock emits a single signal that triggers both chromosome replication and cell division.
Collapse
Affiliation(s)
- Masamichi Kohiyama
- Institut Jacques Monod, Université Paris Cité, CNRS, 75013 Paris, France;
| | - John Herrick
- Independent Researcher, 3 rue des Jeûneurs, 75002 Paris, France;
| | - Vic Norris
- CBSA UR 4312, University of Rouen Normandy, University of Caen Normandy, Normandy University, 76000 Rouen, France
| |
Collapse
|
3
|
The Activity of Calcium Glycerophosphate and Fluoride against Cariogenic Biofilms of Streptococcus mutans and Candida albicans Formed In Vitro. Antibiotics (Basel) 2023; 12:antibiotics12020422. [PMID: 36830332 PMCID: PMC9952171 DOI: 10.3390/antibiotics12020422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 01/03/2023] [Accepted: 01/06/2023] [Indexed: 02/25/2023] Open
Abstract
This study evaluated the effects of calcium glycerophosphate (CaGP), with or without fluoride (F), on dual-species biofilms of Streptococcus mutans and Candida albicans. The biofilms were treated three times with 0.125, 0.25, and 0.5% CaGP solutions, with or without 500 ppm F (NaF). Additionally, 500 and 1100 ppm F-solutions and artificial saliva served as controls. After the final treatment, the microbial viability and biofilm structure, metabolic activity, total biomass production, and the composition of the extracellular matrix composition were analyzed. Regardless of the presence of F, 0.25 and 0.5% CaGP promoted a higher biomass production and metabolic activity increase than the controls (p < 0.05). F-free CaGP solutions reduced bacterial cell population significantly more than the 500 ppm F group or the negative control (p < 0.05). All the groups reduced the proteins, and 0.5% CaGP combined with F led to the highest reduction in the carbohydrate and nucleic acids content of the extracellular matrix (p < 0.05). It can be concluded that CaGP alone affected the number of bacterial cells and, when combined with F, reduced its production of biomass, metabolic activity, and the expression of the extracellular matrix components.
Collapse
|
4
|
Konto-Ghiorghi Y, Norris V. Hypothesis: nucleoid-associated proteins segregate with a parental DNA strand to generate coherent phenotypic diversity. Theory Biosci 2020; 140:17-25. [PMID: 33095418 DOI: 10.1007/s12064-020-00323-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Accepted: 10/12/2020] [Indexed: 01/07/2023]
Abstract
The generation of a phenotypic diversity that is coherent across a bacterial population is a fundamental problem. We propose here that the DNA strand-specific segregation of certain nucleoid-associated proteins or NAPs results in these proteins being asymmetrically distributed to the daughter cells. We invoke a variety of mechanisms as responsible for this asymmetrical segregation including those based on differences between the leading and lagging strands, post-translational modifications, oligomerisation and association with membrane domains.
Collapse
Affiliation(s)
- Yoan Konto-Ghiorghi
- Laboratory of Microbiology Signals and Microenvironment, EA 4312, University of Rouen, 76821, Mont Saint Aignan, France
| | - Vic Norris
- Laboratory of Microbiology Signals and Microenvironment, EA 4312, University of Rouen, 76821, Mont Saint Aignan, France.
| |
Collapse
|
5
|
Gilabert JA. Cytoplasmic Calcium Buffering: An Integrative Crosstalk. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1131:163-182. [PMID: 31646510 DOI: 10.1007/978-3-030-12457-1_7] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Calcium (Ca2+) buffering is part of an integrative crosstalk between different mechanisms and elements involved in the control of free Ca2+ ions persistence in the cytoplasm and hence, in the Ca2+-dependence of many intracellular processes. Alterations of Ca2+ homeostasis and signaling from systemic to subcellular levels also play a pivotal role in the pathogenesis of many diseases.Compared with Ca2+ sequestration towards intracellular Ca2+ stores, Ca2+ buffering is a rapid process occurring in a subsecond scale. Any molecule (or binding site) with the ability to bind Ca2+ ions could be considered, at least in principle, as a buffer. However, the term Ca2+ buffer is applied only to a small subset of Ca2+ binding proteins containing acidic side-chain residues.Ca2+ buffering in the cytoplasm mainly relies on mobile and immobile or fixed buffers controlling the diffusion of free Ca2+ ions inside the cytosol both temporally and spatially. Mobility of buffers depends on their molecular weight, but other parameters as their concentration, affinity for Ca2+ or Ca2+ binding and dissociation kinetics next to their diffusional mobility also contribute to make Ca2+ signaling one of the most complex signaling activities of the cell.The crosstalk between all the elements involved in the intracellular Ca2+ dynamics is a process of extreme complexity due to the diversity of structural and molecular elements involved but permit a highly regulated spatiotemporal control of the signal mediated by Ca2+ ions. The basis of modeling tools to study Ca2+ dynamics are also presented.
Collapse
Affiliation(s)
- Juan A Gilabert
- Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Complutense University of Madrid, Madrid, Spain.
| |
Collapse
|
6
|
Norris V, Krylov SN, Agarwal PK, White GJ. Synthetic, Switchable Enzymes. J Mol Microbiol Biotechnol 2017; 27:117-127. [PMID: 28448969 DOI: 10.1159/000464443] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The construction of switchable, radiation-controlled, aptameric enzymes - "swenzymes" - is, in principle, feasible. We propose a strategy to make such catalysts from 2 (or more) aptamers each selected to bind specifically to one of the substrates in, for example, a 2-substrate reaction. Construction of a combinatorial library of candidate swenzymes entails selecting a set of a million aptamers that bind one substrate and a second set of a million aptamers that bind the second substrate; the aptamers in these sets are then linked pairwise by a linker, thus bringing together the substrates. In the presence of the substrates, some linked aptamer pairs catalyze the reaction when exposed to external energy in the form of a specific frequency of low-intensity, nonionizing electromagnetic or acoustic radiation. Such swenzymes are detected via a separate product-capturing aptamer that changes conformation on capturing the product; this altered conformation allows it (1) to bind to every potential swenzyme in its vicinity (thereby giving a higher probability of capture to the swenzymes that generate the product) and (2) to bind to a sequence on a magnetic bead (thereby permitting purification of the swenzyme plus product-capturing aptamer by precipitation). Attempts to implement the swenzyme strategy may help elucidate fundamental problems in enzyme catalysis.
Collapse
Affiliation(s)
- Vic Norris
- Theoretical Biology Unit, EA 4312, Department of Biology, University of Rouen, Mont Saint Aignan, France
| | | | | | | |
Collapse
|
7
|
Norris V, Ripoll C, Thellier M. The theater management model of plant memory. PLANT SIGNALING & BEHAVIOR 2015; 10:e976157. [PMID: 25482789 PMCID: PMC4622483 DOI: 10.4161/15592324.2014.976157] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 08/23/2014] [Accepted: 08/25/2014] [Indexed: 06/04/2023]
Abstract
The existence of a memory in plants raises several fundamental questions. What might be the function of a plant memory? How might it work? Which molecular mechanisms might be responsible? Here, we sketch out the landscape of plant memory with particular reference to the concepts of functioning-dependent structures and competitive coherence. We illustrate how these concepts might be relevant with reference to the metaphor of a traveling, avant-garde theater company and we suggest how using a program that simulates competitive coherence might help answer some of the questions about plant memory.
Collapse
Affiliation(s)
- Vic Norris
- Department of Biology; University of Rouen; Aignan, France
| | - Camille Ripoll
- Department of Biology; University of Rouen; Aignan, France
| | | |
Collapse
|
8
|
Norris V, Reusch RN, Igarashi K, Root-Bernstein R. Molecular complementarity between simple, universal molecules and ions limited phenotype space in the precursors of cells. Biol Direct 2014; 10:28. [PMID: 25470982 PMCID: PMC4264330 DOI: 10.1186/s13062-014-0028-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 11/24/2014] [Indexed: 01/29/2023] Open
Abstract
Background Fundamental problems faced by the protocells and their modern descendants include how to go from one phenotypic state to another; escape from a basin of attraction in the space of phenotypes; reconcile conflicting growth and survival strategies (and thereby live on ‘the scales of equilibria’); and create a coherent, reproducible phenotype from a multitude of constituents. Presentation of the hypothesis The solutions to these problems are likely to be found with the organic and inorganic molecules and inorganic ions that constituted protocells, which we term SUMIs for Simple Universal Molecules and Ions. These SUMIs probably included polyphosphate (PolyP) as a source of energy and of phosphate; poly-(R)-3-hydroxybutyrate (PHB) as a source of carbon and as a transporter in association with PolyP; polyamines as a source of nitrogen; lipids as precursors of membranes; as well as peptides, nucleic acids, and calcium. Here, we explore the hypothesis that the direct interactions between PHB, PolyP, polyamines and lipids – modulated by calcium – played a central role in solving the fundamental problems faced by early and modern cells. Testing the hypothesis We review evidence that SUMIs (1) were abundant and available to protocells; (2) are widespread in modern cells; (3) interact with one another and other cellular constituents to create structures with new functions surprisingly similar to those of proteins and RNA; (4) are essential to creating coherent phenotypes in modern bacteria. SUMIs are therefore natural candidates for reducing the immensity of phenotype space and making the transition from a “primordial soup” to living cells. Implications of the hypothesis We discuss the relevance of the SUMIs and their interactions to the ideas of molecular complementarity, composomes (molecular aggregates with hereditary properties based on molecular complementarity), and a prebiotic ecology of co-evolving populations of composomes. In particular, we propose that SUMIs might limit the initial phenotype space of composomes in a coherent way. As examples, we propose that acidocalcisomes arose from interactions and self-selection among SUMIs and that the phosphorylation of proteins in modern cells had its origin in the covalent modification of proteins by PHB. Reviewers This article was reviewed by Doron Lancet and Kepa Ruiz-Mirazo.
Collapse
|
9
|
Friesen DE, Craddock TJA, Kalra AP, Tuszynski JA. Biological wires, communication systems, and implications for disease. Biosystems 2014; 127:14-27. [PMID: 25448891 DOI: 10.1016/j.biosystems.2014.10.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 10/30/2014] [Accepted: 10/31/2014] [Indexed: 12/14/2022]
Abstract
Microtubules, actin, and collagen are macromolecular structures that compose a large percentage of the proteins in the human body, helping form and maintain both intracellular and extracellular structure. They are biological wires and are structurally connected through various other proteins. Microtubules (MTs) have been theorized to be involved in classical and quantum information processing, and evidence continues to suggest possible semiconduction through MTs. The previous Dendritic Cytoskeleton Information Processing Model has hypothesized how MTs and actin form a communication network in neurons. Here, we review information transfer possibilities involving MTs, actin, and collagen, and the evidence of an organism-wide high-speed communication network that may regulate morphogenesis and cellular proliferation. The direct and indirect evidence in support of this hypothesis, and implications for chronic diseases such as cancer and neurodegenerative diseases are discussed.
Collapse
Affiliation(s)
- Douglas E Friesen
- Department of Oncology, University of Alberta, Edmonton, Alberta T6G 1Z2, Canada
| | - Travis J A Craddock
- Center for Psychological Studies, Graduate School of Computer and Information Sciences, College of Osteopathic Medicine, Nova Southeastern University, Ft. Lauderdale, FL 33314, USA; Clinical Systems Biology Group, Institute for Neuro-Immune Medicine, Nova Southeastern University, Ft. Lauderdale, FL 33328, USA
| | - Aarat P Kalra
- Department of Chemistry, Dayalbagh Educational Institute, Agra 282005, India
| | - Jack A Tuszynski
- Department of Oncology, University of Alberta, Edmonton, Alberta T6G 1Z2, Canada; Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada.
| |
Collapse
|
10
|
Norris V, Amar P, Legent G, Ripoll C, Thellier M, Ovádi J. Sensor potency of the moonlighting enzyme-decorated cytoskeleton: the cytoskeleton as a metabolic sensor. BMC BIOCHEMISTRY 2013; 14:3. [PMID: 23398642 PMCID: PMC3577492 DOI: 10.1186/1471-2091-14-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 01/22/2013] [Indexed: 11/10/2022]
Abstract
Background There is extensive evidence for the interaction of metabolic enzymes with the eukaryotic cytoskeleton. The significance of these interactions is far from clear. Presentation of the hypothesis In the cytoskeletal integrative sensor hypothesis presented here, the cytoskeleton senses and integrates the general metabolic activity of the cell. This activity depends on the binding to the cytoskeleton of enzymes and, depending on the nature of the enzyme, this binding may occur if the enzyme is either active or inactive but not both. This enzyme-binding is further proposed to stabilize microtubules and microfilaments and to alter rates of GTP and ATP hydrolysis and their levels. Testing the hypothesis Evidence consistent with the cytoskeletal integrative sensor hypothesis is presented in the case of glycolysis. Several testable predictions are made. There should be a relationship between post-translational modifications of tubulin and of actin and their interaction with metabolic enzymes. Different conditions of cytoskeletal dynamics and enzyme-cytoskeleton binding should reveal significant differences in local and perhaps global levels and ratios of ATP and GTP. The different functions of moonlighting enzymes should depend on cytoskeletal binding. Implications of the hypothesis The physical and chemical effects arising from metabolic sensing by the cytoskeleton would have major consequences on cell shape, dynamics and cell cycle progression. The hypothesis provides a framework that helps the significance of the enzyme-decorated cytoskeleton be determined.
Collapse
Affiliation(s)
- Vic Norris
- EA 3829, Faculté des Sciences de l'Université de Rouen, 76821, Mont Saint Aignan Cedex, France.
| | | | | | | | | | | |
Collapse
|
11
|
Thellier M, Lüttge U. Plant memory: a tentative model. PLANT BIOLOGY (STUTTGART, GERMANY) 2013; 15:1-12. [PMID: 23121044 DOI: 10.1111/j.1438-8677.2012.00674.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Accepted: 08/09/2012] [Indexed: 05/20/2023]
Abstract
All memory functions have molecular bases, namely in signal reception and transduction, and in storage and recall of information. Thus, at all levels of organisation living organisms have some kind of memory. In plants one may distinguish two types. There are linear pathways from reception of signals and propagation of effectors to a type of memory that may be described by terms such as learning, habituation or priming. There is a storage and recall memory based on a complex network of elements with a high degree of integration and feedback. The most important elements envisaged are calcium waves, epigenetic modifications of DNA and histones, and regulation of timing via a biological clock. Experiments are described that document the occurrence of the two sorts of memory and which show how they can be distinguished. A schematic model of plant memory is derived as emergent from integration of the various modules. Possessing the two forms of memory supports the fitness of plants in response to environmental stimuli and stress.
Collapse
|
12
|
Norris V, Amar P. Chromosome Replication in Escherichia coli: Life on the Scales. Life (Basel) 2012; 2:286-312. [PMID: 25371267 PMCID: PMC4187155 DOI: 10.3390/life2040286] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2012] [Revised: 10/01/2012] [Accepted: 10/15/2012] [Indexed: 12/22/2022] Open
Abstract
At all levels of Life, systems evolve on the 'scales of equilibria'. At the level of bacteria, the individual cell must favor one of two opposing strategies and either take risks to grow or avoid risks to survive. It has been proposed in the Dualism hypothesis that the growth and survival strategies depend on non-equilibrium and equilibrium hyperstructures, respectively. It has been further proposed that the cell cycle itself is the way cells manage to balance the ratios of these types of hyperstructure so as to achieve the compromise solution of living on the two scales. Here, we attempt to re-interpret a major event, the initiation of chromosome replication in Escherichia coli, in the light of scales of equilibria. This entails thinking in terms of hyperstructures as responsible for intensity sensing and quantity sensing and how this sensing might help explain the role of the DnaA protein in initiation of replication. We outline experiments and an automaton approach to the cell cycle that should test and refine the scales concept.
Collapse
Affiliation(s)
- Vic Norris
- Theoretical Biology Unit, EA 3829, Department of Biology, University of Rouen, 76821, Mont Saint Aignan, France.
| | - Patrick Amar
- Laboratoire de Recherche en Informatique, Université Paris-Sud, and INRIA Saclay - Ile de France, AMIB Project, Orsay, France.
| |
Collapse
|
13
|
Norris V, Menu-Bouaouiche L, Becu JM, Legendre R, Norman R, Rosenzweig JA. Hyperstructure interactions influence the virulence of the type 3 secretion system in yersiniae and other bacteria. Appl Microbiol Biotechnol 2012; 96:23-36. [PMID: 22949045 DOI: 10.1007/s00253-012-4325-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 07/18/2012] [Accepted: 07/18/2012] [Indexed: 01/06/2023]
Abstract
A paradigm shift in our thinking about the intricacies of the host-parasite interaction is required that considers bacterial structures and their relationship to bacterial pathogenesis. It has been proposed that interactions between extended macromolecular assemblies, termed hyperstructures (which include multiprotein complexes), determine bacterial phenotypes. In particular, it has been proposed that hyperstructures can alter virulence. Two such hyperstructures have been characterized in both pathogenic and nonpathogenic bacteria. Present within a number of both human and plant Gram-negative pathogens is the type 3 secretion system (T3SS) injectisome which in some bacteria serves to inject toxic effector proteins directly into targeted host cells resulting in their paralysis and eventual death (but which in other bacteria prevents the death of the host). The injectisome itself comprises multiple protein subunits, which are all essential for its function. The degradosome is another multiprotein complex thought to be involved in cooperative RNA decay and processing of mRNA transcripts and has been very well characterized in nonpathogenic Escherichia coli. Recently, experimental evidence has suggested that a degradosome exists in the yersiniae as well and that its interactions within the pathogens modulate their virulence. Here, we explore the possibility that certain interactions between hyperstructures, like the T3SS and the degradosome, can ultimately influence the virulence potential of the pathogen based upon the physical locations of hyperstructures within the cell.
Collapse
Affiliation(s)
- Vic Norris
- Department of Biology, University of Rouen, 76821 Mont-Saint-Aignan, Rouen, France.
| | | | | | | | | | | |
Collapse
|
14
|
Verdus MC, Ripoll C, Norris V, Thellier M. The role of calcium in the recall of stored morphogenetic information by plants. Acta Biotheor 2012; 60:83-97. [PMID: 22286946 DOI: 10.1007/s10441-012-9145-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Accepted: 01/11/2012] [Indexed: 11/24/2022]
Abstract
Flax seedlings grown in the absence of environmental stimuli, stresses and injuries do not form epidermal meristems in their hypocotyls. Such meristems do form when the stimuli are combined with a transient depletion of calcium. These stimuli include the "manipulation stimulus" resulting from transferring the seedlings from germination to growth conditions. If, after a stimulus, calcium depletion is delayed, meristem production is also delayed; in other words, the meristem-production instruction can be memorised. Memorisation includes both storage and recall of information. Here, we focus on information recall. We show that if the first transient calcium depletion is followed by a second transient depletion there is a new round of meristem production. We also show that if an excess of calcium follows calcium depletion, meristem production is blocked; but if the excess of calcium is in turn followed by another calcium depletion, again there is a new round of meristem production. The same stored information can thus be recalled repeatedly (at least twice). We describe a conceptual model that takes into account these findings.
Collapse
Affiliation(s)
- Marie-Claire Verdus
- Laboratoire AMMIS, CNRS, Faculté des Sciences et Techniques, Université de Rouen, Mont-Saint-Aignan, France
| | | | | | | |
Collapse
|
15
|
Norris V, Zemirline A, Amar P, Audinot JN, Ballet P, Ben-Jacob E, Bernot G, Beslon G, Cabin A, Fanchon E, Giavitto JL, Glade N, Greussay P, Grondin Y, Foster JA, Hutzler G, Jost J, Kepes F, Michel O, Molina F, Signorini J, Stano P, Thierry AR. Computing with bacterial constituents, cells and populations: from bioputing to bactoputing. Theory Biosci 2011; 130:211-28. [PMID: 21384168 PMCID: PMC3163788 DOI: 10.1007/s12064-010-0118-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2010] [Accepted: 12/15/2010] [Indexed: 10/29/2022]
Abstract
The relevance of biological materials and processes to computing-alias bioputing-has been explored for decades. These materials include DNA, RNA and proteins, while the processes include transcription, translation, signal transduction and regulation. Recently, the use of bacteria themselves as living computers has been explored but this use generally falls within the classical paradigm of computing. Computer scientists, however, have a variety of problems to which they seek solutions, while microbiologists are having new insights into the problems bacteria are solving and how they are solving them. Here, we envisage that bacteria might be used for new sorts of computing. These could be based on the capacity of bacteria to grow, move and adapt to a myriad different fickle environments both as individuals and as populations of bacteria plus bacteriophage. New principles might be based on the way that bacteria explore phenotype space via hyperstructure dynamics and the fundamental nature of the cell cycle. This computing might even extend to developing a high level language appropriate to using populations of bacteria and bacteriophage. Here, we offer a speculative tour of what we term bactoputing, namely the use of the natural behaviour of bacteria for calculating.
Collapse
Affiliation(s)
- Vic Norris
- Epigenomics Project, Genopole Campus 1, Bât. Genavenir 6, 5 rue Henri Desbruères, 91030, Évry Cedex, France.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Norris V. Speculations on the initiation of chromosome replication in Escherichia coli: the dualism hypothesis. Med Hypotheses 2011; 76:706-16. [PMID: 21349650 DOI: 10.1016/j.mehy.2011.02.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2010] [Revised: 01/23/2011] [Accepted: 02/01/2011] [Indexed: 10/18/2022]
Abstract
The exact nature of the mechanism that triggers initiation of chromosome replication in the best understood of all organisms, Escherichia coli, remains mysterious. Here, I suggest that this mechanism evolved in response to the problems that arise if chromosome replication does not occur. E. coli is now known to be highly structured. This leads me to propose a mechanism for initiation of replication based on the dynamics of large assemblies of molecules and macromolecules termed hyperstructures. In this proposal, hyperstructures and their constituents are put into two classes, non-equilibrium and equilibrium, that spontaneously separate and that are appropriate for life in either good or bad conditions. Maintaining the right ratio(s) of non-equilibrium to equilibrium hyperstructures is therefore a major challenge for cells. I propose that this maintenance entails a major transfer of material from equilibrium to non-equilibrium hyperstructures once per cell and I further propose that this transfer times the cell cycle. More specifically, I speculate that the dialogue between hyperstructures involves the structuring of water and the condensation of cations and that one of the outcomes of ion condensation on ribosomal hyperstructures and decondensation from the origin hyperstructure is the separation of strands at oriC responsible for triggering initiation of replication. The dualism hypothesis that comes out of these speculations may help integrate models for initiation of replication, chromosome segregation and cell division with the 'prebiotic ecology' scenario of the origins of life.
Collapse
Affiliation(s)
- Vic Norris
- AMMIS Laboratory, EA 3829, Department of Biology, University of Rouen, 76821 Mont Saint Aignan, France.
| |
Collapse
|
17
|
Lange K. Fundamental role of microvilli in the main functions of differentiated cells: Outline of an universal regulating and signaling system at the cell periphery. J Cell Physiol 2010; 226:896-927. [PMID: 20607764 DOI: 10.1002/jcp.22302] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
|
18
|
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.
Collapse
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:
| |
Collapse
|
19
|
Norris V, Bresson-Dumont H, Gardea E, Reusch RN, Gruber D. Hypothesis: Poly-(R)-3-hydroxybutyrate is a major factor in intraocular pressure. Med Hypotheses 2009; 73:398-401. [DOI: 10.1016/j.mehy.2008.10.036] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2008] [Revised: 04/12/2009] [Accepted: 10/15/2008] [Indexed: 01/27/2023]
|
20
|
He X, Wu C, Yarbrough D, Sim L, Niu G, Merritt J, Shi W, Qi F. The cia operon of Streptococcus mutans encodes a unique component required for calcium-mediated autoregulation. Mol Microbiol 2008; 70:112-26. [PMID: 18681938 DOI: 10.1111/j.1365-2958.2008.06390.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Streptococcus mutans is a primary pathogen for dental caries in humans. CiaR and CiaH of S. mutans comprise a two-component signal transduction system (TCS) involved in regulating various virulent factors. However, the signal that triggers the CiaRH response remains unknown. In this study, we show that calcium is a signal for regulation of the ciaRH operon, and that a double-glycine-containing small peptide encoded within the ciaRH operon (renamed ciaX) mediates this regulation. CiaX contains a serine + aspartate (SD) domain that is shared by calcium-binding proteins. A markerless in-frame deletion of ciaX reduced ciaRH operon expression and diminished the calcium repression of operon transcription. Point mutations of the SD domain resulted in the same phenotype as the in-frame deletion, indicating that the SD domain is required for CiaX function. Further characterization of ciaX demonstrated that it is involved in calcium-mediated biofilm formation. Furthermore, inactivation of ciaR or ciaH led to the same phenotype as the in-frame deletion of ciaX, suggesting that all three genes are involved in the same regulatory pathway. Sequence analysis and real-time RT-PCR identified a putative CiaR binding site upstream of ciaX. We conclude that the ciaXRH operon is a three-component, self-regulatory system modulating cellular functions in response to calcium.
Collapse
Affiliation(s)
- Xuesong He
- UCLA School of Dentistry, Los Angeles, CA 90095, USA
| | | | | | | | | | | | | | | |
Collapse
|
21
|
pH and monovalent cations regulate cytosolic free Ca2+ in E. coli. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:1415-22. [DOI: 10.1016/j.bbamem.2008.02.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2007] [Revised: 01/28/2008] [Accepted: 02/12/2008] [Indexed: 11/24/2022]
|
22
|
Norris V, den Blaauwen T, Doi RH, Harshey RM, Janniere L, Jiménez-Sánchez A, Jin DJ, Levin PA, Mileykovskaya E, Minsky A, Misevic G, Ripoll C, Saier M, Skarstad K, Thellier M. Toward a hyperstructure taxonomy. Annu Rev Microbiol 2007; 61:309-29. [PMID: 17896876 DOI: 10.1146/annurev.micro.61.081606.103348] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Bacterial cells contain many large, spatially extended assemblies of ions, molecules, and macromolecules, called hyperstructures, that are implicated in functions that range from DNA replication and cell division to chemotaxis and secretion. Interactions between these hyperstructures would create a level of organization intermediate between macromolecules and the cell itself. To explore this level, a taxonomy is needed. Here, we describe classification criteria based on the form of the hyperstructure and on the processes responsible for this form. These processes include those dependent on coupled transcription-translation, protein-protein affinities, chromosome site-binding by protein, and membrane structures. Various combinations of processes determine the formation, maturation, and demise of many hyperstructures that therefore follow a trajectory within the space of classification by form/process. Hence a taxonomy by trajectory may be desirable. Finally, we suggest that working toward a taxonomy based on speculative interactions between hyperstructures promises most insight into life at this level.
Collapse
Affiliation(s)
- Vic Norris
- Department of Science, University of Rouen, 76821 Mont Saint Aignan Cedex, France.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
23
|
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]
|
24
|
Verdus MC, Le Sceller L, Norris V, Thellier M, Ripoll C. Pharmacological evidence for calcium involvement in the long-term processing of abiotic stimuli in plants. PLANT SIGNALING & BEHAVIOR 2007; 2:212-220. [PMID: 19516991 PMCID: PMC2634131 DOI: 10.4161/psb.2.4.4368] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2007] [Accepted: 04/30/2007] [Indexed: 05/27/2023]
Abstract
Information about abiotic conditions is stored for long periods in plants and, in flax seedlings, can lead to the production of meristems. To investigate the underlying mechanism, flax seedlings were given abiotic stimuli that included a mechanical stimulus (by manipulation), one or two cold shocks, a slow cold treatment and a drought stress and, if these seedlings were then subjected to a temporary (1 to 3 days) depletion of calcium, epidermal meristems were produced in the seedling hypocotyls. This production was inhibited by the addition to the nutrient media of EGTA, ruthenium red, lanthanum or gadolinium that affect calcium availability or calcium transport. Use of these agents revealed a period of vulnerability in information processing that was less than two min for mechanical stimuli and over five min for other abiotic stimuli, consistent with information about mechanical stimuli being stored particularly fast. We propose that external calcium is needed for the transduction/storage of the information for meristem production whilst a temporary depletion of external calcium is needed for the actual production of meristems. Such roles for calcium would be consistent with a mechanism based on ion condensation on charged polymers.
Collapse
Affiliation(s)
- Marie-Claire Verdus
- Laboratoire AMMIS; Faculté des Sciences de l'Université de Rouen; Mont-Saint-Aignan, France
| | | | | | | | | |
Collapse
|
25
|
Norris V, den Blaauwen T, Cabin-Flaman A, Doi RH, Harshey R, Janniere L, Jimenez-Sanchez A, Jin DJ, Levin PA, Mileykovskaya E, Minsky A, Saier M, Skarstad K. Functional taxonomy of bacterial hyperstructures. Microbiol Mol Biol Rev 2007; 71:230-53. [PMID: 17347523 PMCID: PMC1847379 DOI: 10.1128/mmbr.00035-06] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The levels of organization that exist in bacteria extend from macromolecules to populations. Evidence that there is also a level of organization intermediate between the macromolecule and the bacterial cell is accumulating. This is the level of hyperstructures. Here, we review a variety of spatially extended structures, complexes, and assemblies that might be termed hyperstructures. These include ribosomal or "nucleolar" hyperstructures; transertion hyperstructures; putative phosphotransferase system and glycolytic hyperstructures; chemosignaling and flagellar hyperstructures; DNA repair hyperstructures; cytoskeletal hyperstructures based on EF-Tu, FtsZ, and MreB; and cell cycle hyperstructures responsible for DNA replication, sequestration of newly replicated origins, segregation, compaction, and division. We propose principles for classifying these hyperstructures and finally illustrate how thinking in terms of hyperstructures may lead to a different vision of the bacterial cell.
Collapse
Affiliation(s)
- Vic Norris
- Department of Science, University of Rouen, 76821 Mont Saint Aignan Cedex, France.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
26
|
Campbell AK, Naseem R, Wann K, Holland IB, Matthews SB. Fermentation product butane 2,3-diol induces Ca2+ transients in E. coli through activation of lanthanum-sensitive Ca2+ channels. Cell Calcium 2007; 41:97-106. [PMID: 16842848 DOI: 10.1016/j.ceca.2006.05.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2006] [Revised: 05/11/2006] [Accepted: 05/14/2006] [Indexed: 12/17/2022]
Abstract
The results here are the first demonstration of a physiological agonist opening Ca2+ channels in bacteria. Bacteria in the gut ferment glucose and other substrates, producing alcohols, diols, ketones and acids, that play a key role in lactose intolerance, through the activation of Ca2+ and other ion channels in host cells and neighbouring bacteria. Here we show butane 2,3-diol (5-200mM; half maximum 25mM) activates Ca2+ transients in E. coli, monitored by aequorin. Ca2+-transient magnitude depended on external Ca2+ (0.1-10mM). meso-Butane 2,3-diol was approximately twice as potent as 2R,3R (-) and 2S,3S (+) butane 2,3-diol. There were no detectable effects on cytosolic free Ca2+ of butane 1,3-diol, butane 1,4-diol and ethylene glycol. The glycerol fermentation product propane 1,3-diol only induced significant Ca2+ transients in 10mM external Ca2. Ca2+ butane 2,3-diol Ca2+ transients were due to activation of Ca2+ influx, followed by activation of Ca2+ efflux. The effect of butane 2,3-diol was abolished by La3+, and markedly reduced as a function of growth phase. These results were consistent with butane 2,3-diol activating a novel La3+-sensitive Ca2+ channel. They have important implications for the role of butane 2,3-diol and Ca2+ in bacterial-host cell signalling.
Collapse
Affiliation(s)
- Anthony K Campbell
- Department of Medical Biochemistry and Immunology, School of Medicine, Tenovus Building, Cardiff University, Heath Park, Cardiff CF14 4XN, UK.
| | | | | | | | | |
Collapse
|
27
|
Thellier M, Legent G, Amar P, Norris V, Ripoll C. Steady-state kinetic behaviour of functioning-dependent structures. FEBS J 2006; 273:4287-99. [PMID: 16939622 DOI: 10.1111/j.1742-4658.2006.05425.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A fundamental problem in biochemistry is that of the nature of the coordination between and within metabolic and signalling pathways. It is conceivable that this coordination might be assured by what we term functioning-dependent structures (FDSs), namely those assemblies of proteins that associate with one another when performing tasks and that disassociate when no longer performing them. To investigate a role in coordination for FDSs, we have studied numerically the steady-state kinetics of a model system of two sequential monomeric enzymes, E(1) and E(2). Our calculations show that such FDSs can display kinetic properties that the individual enzymes cannot. These include the full range of basic input/output characteristics found in electronic circuits such as linearity, invariance, pulsing and switching. Hence, FDSs can generate kinetics that might regulate and coordinate metabolism and signalling. Finally, we suggest that the occurrence of terms representative of the assembly and disassembly of FDSs in the classical expression of the density of entropy production are characteristic of living systems.
Collapse
Affiliation(s)
- Michel Thellier
- Laboratoire 'Assemblages moléculaires: modélisation et imagerie SIMS', Faculté des Sciences de l'Université de Rouen, Mont-Saint-Aignan Cedex, France.
| | | | | | | | | |
Collapse
|
28
|
Abstract
What is biological complexity? How many sorts exist? Are there levels of complexity? How are they related to one another? How is complexity related to the emergence of new phenotypes? To try to get to grips with these questions, we consider the archetype of a complex biological system, Escherichia coli. We take the position that E. coli has been selected to survive adverse conditions and to grow in favourable ones and that many other complex systems undergo similar selection. We invoke the concept of hyperstructures which constitute a level of organisation intermediate between macromolecules and cells. We also invoke a new concept, competitive coherence, to describe how phenotypes are created by a competition between maintaining a consistent story over time and creating a response that is coherent with respect to both internal and external conditions. We suggest how these concepts lead to parameters suitable for describing the rich form of complexity termed hypercomplexity and we propose a relationship between competitive coherence and emergence.
Collapse
Affiliation(s)
- Vic Norris
- Assemblages Moléculaires, Modélisation et Imagerie SIMS, FRE CNRS 2829, Faculté de Sciences et Techniques de Rouen, 76821, Mont Saint Aignan, France.
| | | | | |
Collapse
|
29
|
Priel A, Tuszynski JA, Woolf NJ. Transitions in microtubule C-termini conformations as a possible dendritic signaling phenomenon. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2005; 35:40-52. [PMID: 16184388 DOI: 10.1007/s00249-005-0003-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2005] [Revised: 05/12/2005] [Accepted: 05/23/2005] [Indexed: 10/25/2022]
Abstract
We model the dynamical states of the C-termini of tubulin dimers that comprise neuronal microtubules. We use molecular dynamics and other computational tools to explore the time-dependent behavior of conformational states of a C-terminus of tubulin within a microtubule and assume that each C-terminus interacts via screened Coulomb forces with the surface of a tubulin dimer, with neighboring C-termini and also with any adjacent microtubule-associated protein 2 (MAP2). Each C-terminus can either bind to the tubulin surface via one of the several positively charged regions or can be allowed to explore the space available in the solution surrounding the dimer. We find that the preferential orientation of each C-terminus is away from the tubulin surface but binding to the surface may also take place, albeit at a lower probability. The results of our model suggest that perturbations generated by the C-termini interactions with counterions surrounding a MAP2 may propagate over distances greater than those between adjacent microtubules. Thus, the MAP2 structure is able to act as a kind of biological wire (or a cable) transmitting local electrostatic perturbations resulting in ionic concentration gradients from one microtubule to another. We briefly discuss the implications the current dynamic modeling may have on synaptic activation and potentiation.
Collapse
Affiliation(s)
- Avner Priel
- Department of Physics, University of Alberta Edmonton, AB, T6G 2J1, Canada
| | | | | |
Collapse
|
30
|
Abstract
Molecular interactions are the language that molecules use to communicate recognition, binding, and regulation, events central to biological control mechanisms. Traditionally, such interactions involve direct, atom-to-atom, noncovalent contacts, or indirect contacts bridged by relatively fixed solvent molecules. Here we discuss a third class of molecular communication that, to date, has received less experimental attention, namely solvent-mediated communication between noncontacting macromolecules. This form of communication can be understood in terms of fundamental, well-established principles (coupled equilibria and linkage thermodynamics) that govern interactions between individual polymers and their solutions. In contrast to simple solutions used in laboratory studies, biological systems contain a multitude of nominally noninteracting biopolymers within the same solution environment. The exquisite control of biological function requires some form of communication between many of these solution components, even in the absence of direct and/or indirect contacts. Such communication must be considered when describing potential mechanisms of biological regulation.
Collapse
Affiliation(s)
- Jens Völker
- Department of Chemistry and Chemical Biology, Rutgers-The State University of New Jersey, Piscataway, New Jersey 08854-8087, USA.
| | | |
Collapse
|
31
|
Abstract
Whereas the importance of calcium as a cell regulator is well established in eukaryotes, the role of calcium in prokaryotes is still elusive. Over the past few years, there has been an increased interest in the role of calcium in bacteria. It has been demonstrated that as in eukaryotic organisms, the intracellular calcium concentration in prokaryotes is tightly regulated ranging from 100 to 300 nM. It has been found that calcium ions are involved in the maintenance of cell structure, motility, transport and cell differentiation processes such as sporulation, heterocyst formation and fruiting body development. In addition, a number of calcium-binding proteins have been isolated in several prokaryotic organisms. The characterization of these proteins and the identification of other factors suggest the possibility that calcium signal transduction exists in bacteria. This review presents recent developments of calcium in bacteria as it relates to signal transduction.
Collapse
Affiliation(s)
- Delfina C Dominguez
- College of Health Sciences, The University of Texas at El Paso, El Paso, TX 79902, USA.
| |
Collapse
|