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Bearne SL. Biochemical communication between filament-forming enzymes: Potential Regulatory Roles of Metabolites in Enzyme Co-assemblies with CTP Synthase. Bioessays 2024; 46:e2400063. [PMID: 38975656 DOI: 10.1002/bies.202400063] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 05/05/2024] [Accepted: 05/08/2024] [Indexed: 07/09/2024]
Abstract
A host of metabolic enzymes reversibly self-assemble to form membrane-less, intracellular filaments under normal physiological conditions and in response to stress. Often, these enzymes reside at metabolic control points, suggesting that filament formation affords an additional regulatory mechanism. Examples include cytidine-5'-triphosphate (CTP) synthase (CTPS), which catalyzes the rate-limiting step for the de novo biosynthesis of CTP; inosine-5'-monophosphate dehydrogenase (IMPDH), which controls biosynthetic access to guanosine-5'-triphosphate (GTP); and ∆1-pyrroline-5-carboxylate (P5C) synthase (P5CS) that catalyzes the formation of P5C, which links the Krebs cycle, urea cycle, and proline metabolism. Intriguingly, CTPS can exist in co-assemblies with IMPDH or P5CS. Since GTP is an allosteric activator of CTPS, the association of CTPS and IMPDH filaments accords with the need to coordinate pyrimidine and purine biosynthesis. Herein, a hypothesis is presented furnishing a biochemical connection underlying co-assembly of CTPS and P5CS filaments - potent inhibition of CTPS by glutamate γ-semialdehyde, the open-chain form of P5C.
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Affiliation(s)
- Stephen L Bearne
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
- Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, Canada
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2
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Pilic J, Gottschalk B, Bourgeois B, Habisch H, Koshenov Z, Oflaz FE, Erdogan YC, Miri SM, Yiğit EN, Aydın MŞ, Öztürk G, Eroglu E, Shoshan-Barmatz V, Madl T, Graier WF, Malli R. Hexokinase 1 forms rings that regulate mitochondrial fission during energy stress. Mol Cell 2024; 84:2732-2746.e5. [PMID: 38981483 DOI: 10.1016/j.molcel.2024.06.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 04/30/2024] [Accepted: 06/11/2024] [Indexed: 07/11/2024]
Abstract
Metabolic enzymes can adapt during energy stress, but the consequences of these adaptations remain understudied. Here, we discovered that hexokinase 1 (HK1), a key glycolytic enzyme, forms rings around mitochondria during energy stress. These HK1-rings constrict mitochondria at contact sites with the endoplasmic reticulum (ER) and mitochondrial dynamics protein (MiD51). HK1-rings prevent mitochondrial fission by displacing the dynamin-related protein 1 (Drp1) from mitochondrial fission factor (Mff) and mitochondrial fission 1 protein (Fis1). The disassembly of HK1-rings during energy restoration correlated with mitochondrial fission. Mechanistically, we identified that the lack of ATP and glucose-6-phosphate (G6P) promotes the formation of HK1-rings. Mutations that affect the formation of HK1-rings showed that HK1-rings rewire cellular metabolism toward increased TCA cycle activity. Our findings highlight that HK1 is an energy stress sensor that regulates the shape, connectivity, and metabolic activity of mitochondria. Thus, the formation of HK1-rings may affect mitochondrial function in energy-stress-related pathologies.
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Affiliation(s)
- Johannes Pilic
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/4, 8010 Graz, Austria
| | - Benjamin Gottschalk
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/4, 8010 Graz, Austria
| | - Benjamin Bourgeois
- BioTechMed Graz, Mozartgasse 12/2, 8010 Graz, Austria; Otto Loewi Research Center, Medical Chemistry, Medical University of Graz, 8010 Graz, Austria
| | - Hansjörg Habisch
- Otto Loewi Research Center, Medical Chemistry, Medical University of Graz, 8010 Graz, Austria
| | - Zhanat Koshenov
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/4, 8010 Graz, Austria
| | - Furkan E Oflaz
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/4, 8010 Graz, Austria
| | - Yusuf C Erdogan
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/4, 8010 Graz, Austria
| | - Seyed M Miri
- Regenerative and Restorative Medicine Research Center (REMER), Research Institute for Health Sciences and Technologies (SABITA), Istanbul Medipol University, 34810 Istanbul, Türkiye; Molecular Biology, Genetics and Bioengineering Program, Faculty of Engineering and Natural Sciences, Sabanci University, 34956 Istanbul, Türkiye
| | - Esra N Yiğit
- Regenerative and Restorative Medicine Research Center (REMER), Research Institute for Health Sciences and Technologies (SABITA), Istanbul Medipol University, 34810 Istanbul, Türkiye; Department of Physiology, International School of Medicine, Istanbul Medipol University, 34810 Istanbul, Türkiye
| | - Mehmet Ş Aydın
- Regenerative and Restorative Medicine Research Center (REMER), Research Institute for Health Sciences and Technologies (SABITA), Istanbul Medipol University, 34810 Istanbul, Türkiye
| | - Gürkan Öztürk
- Regenerative and Restorative Medicine Research Center (REMER), Research Institute for Health Sciences and Technologies (SABITA), Istanbul Medipol University, 34810 Istanbul, Türkiye
| | - Emrah Eroglu
- Regenerative and Restorative Medicine Research Center (REMER), Research Institute for Health Sciences and Technologies (SABITA), Istanbul Medipol University, 34810 Istanbul, Türkiye; Department of Physiology, International School of Medicine, Istanbul Medipol University, 34810 Istanbul, Türkiye
| | - Varda Shoshan-Barmatz
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, 84105 Beer-Sheva, Israel
| | - Tobias Madl
- BioTechMed Graz, Mozartgasse 12/2, 8010 Graz, Austria; Otto Loewi Research Center, Medical Chemistry, Medical University of Graz, 8010 Graz, Austria
| | - Wolfgang F Graier
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/4, 8010 Graz, Austria; BioTechMed Graz, Mozartgasse 12/2, 8010 Graz, Austria
| | - Roland Malli
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/4, 8010 Graz, Austria; BioTechMed Graz, Mozartgasse 12/2, 8010 Graz, Austria; Center for Medical Research, CF Bioimaging, Medical University of Graz, Neue Stiftingtalstraße 6/6, 8010 Graz, Austria.
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3
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Wang Y, Douglas T. Tuning Multistep Biocatalysis through Enzyme and Cofactor Colocalization in Charged Porous Protein Macromolecular Frameworks. ACS APPLIED MATERIALS & INTERFACES 2023; 15:43621-43632. [PMID: 37695852 DOI: 10.1021/acsami.3c10340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/13/2023]
Abstract
Spatial organization of biocatalytic activities is crucial to organisms to efficiently process complex metabolism. Inspired by this mechanism, artificial scaffold structures are designed to harbor functionally coupled biocatalysts, resulting in acellular materials that can complete multistep reactions at high efficiency and low cost. Substrate channeling is an approach for efficiency enhancement of multistep reactions, but fast diffusion of small molecule intermediates poses a major challenge to achieve channeling in vitro. Here, we explore how multistep biocatalysis is affected, and can be modulated, by cofactor-enzyme colocalization within a synthetic bioinspired material. In this material, a heterogeneous protein macromolecular framework (PMF) acts as a porous host matrix for colocalization of two coupled enzymes and their small molecule cofactor, nicotinamide adenine dinucleotide (NAD). After formation of the PMF from a higher order assembly of P22 virus-like particles (VLPs), the enzymes were partitioned into the PMF by covalent attachment and presentation on the VLP exterior. Using a collective property of the PMF (i.e., high density of negative charges in the PMF), NAD molecules were partitioned into the framework via electrostatic interactions after being conjugated to a polycationic species. This effectively controlled the localization and diffusion of NAD, resulting in substrate channeling between the enzymes. Changing ionic strength modulates the PMF-NAD interactions, tuning two properties that impact the multistep efficiency oppositely in response to ionic strength: cofactor partitioning (colocalization with the enzymes) and cofactor mobility (translocation between the enzymes). Within the range tested, we observed a maximum of 5-fold increase or 75% decrease in multistep efficiency as compared to free enzymes in solution, which suggest both the colocalization and the mobility are critical for the multistep efficiency. This work demonstrates utility of collective behaviors, exhibited by hierarchical bioassemblies, in the construction of functional materials for enzyme cascades, which possess properties such as tunable multistep biocatalysis.
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Affiliation(s)
- Yang Wang
- Department of Chemistry, Indiana University, 800 E Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Trevor Douglas
- Department of Chemistry, Indiana University, 800 E Kirkwood Avenue, Bloomington, Indiana 47405, United States
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4
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Golmohammadzadeh M, Sexton DL, Parmar S, Tocheva EI. Advanced imaging techniques: Microscopy. ADVANCES IN APPLIED MICROBIOLOGY 2023; 122:1-25. [PMID: 37085191 DOI: 10.1016/bs.aambs.2023.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
For decades, bacteria were thought of as "bags" of enzymes, lacking organelles and significant subcellular structures. This stood in sharp contrast with eukaryotes, where intracellular compartmentalization and the role of large-scale order had been known for a long time. However, the emerging field of Bacterial Cell Biology has established that bacteria are in fact highly organized, with most macromolecular components having specific subcellular locations that can change depending on the cell's physiological state (Barry & Gitai, 2011; Lenz & Søgaard-Andersen, 2011; Thanbichler & Shapiro, 2008). For example, we now know that many processes in bacteria are orchestrated by cytoskeletal proteins, which polymerize into surprisingly diverse superstructures, such as rings, sheets, and tread-milling rods (Pilhofer & Jensen, 2013). These superstructures connect individual proteins, macromolecular assemblies, and even two neighboring cells, to affect essential higher-order processes including cell division, DNA segregation, and motility. Understanding these processes requires resolving the in vivo dynamics and ultrastructure at different functional stages of the cell, at macromolecular resolution and in 3-dimensions (3D). Fluorescence light microscopy (fLM) of tagged proteins is highly valuable for investigating protein localization and dynamics, and the resolution power of transmission electron microscopy (TEM) is required to elucidate the structure of macromolecular complexes in vivo and in vitro. This chapter summarizes the most recent advances in LM and TEM approaches that have revolutionized our knowledge and understanding of the microbial world.
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Affiliation(s)
- Mona Golmohammadzadeh
- Department of Microbiology and Immunology, Life Sciences Institute, Health Sciences Mall, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Danielle L Sexton
- Department of Microbiology and Immunology, Life Sciences Institute, Health Sciences Mall, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Shweta Parmar
- Department of Microbiology and Immunology, Life Sciences Institute, Health Sciences Mall, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Elitza I Tocheva
- Department of Microbiology and Immunology, Life Sciences Institute, Health Sciences Mall, The University of British Columbia, Vancouver, British Columbia, Canada.
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5
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Nunn AV, Guy GW, Bell JD. Bioelectric Fields at the Beginnings of Life. Bioelectricity 2022; 4:237-247. [PMID: 36636557 PMCID: PMC9810354 DOI: 10.1089/bioe.2022.0012] [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] [Indexed: 01/16/2023] Open
Abstract
The consensus on the origins of life is that it involved organization of prebiotic chemicals according to the underlying principles of thermodynamics to dissipate energy derived from photochemical and/or geochemical sources. Leading theories tend to be chemistry-centric, revolving around either metabolism or information-containing polymers first. However, experimental data also suggest that bioelectricity and quantum effects play an important role in biology, which might suggest that a further factor is required to explain how life began. Intriguingly, in the early part of 20th century, the concept of the "morphogenetic field" was proposed by Gurwitsch to explain how the shape of an organism was determined, while a role for quantum mechanics in biology was suggested by Bohr and Schrödinger, among others. This raises the question as to the potential of these phenomena, especially bioelectric fields, to have been involved in the origin of life. It points to the possibility that as bioelectricity is universally prevalent in biological systems today, it represents a more complex echo of an electromagnetic skeleton which helped shape life into being. It could be argued that as a flow of ions creates an electric field, this could have been pivotal in the formation of an energy dissipating structure, for instance, in deep sea thermal vents. Moreover, a field theory might also hint at the potential involvement of nontrivial quantum effects in life. Not only might this perspective help indicate the origins of morphogenetic fields, but also perhaps suggest where life may have started, and whether metabolism or information came first. It might also help to provide an insight into aging, cancer, consciousness, and, perhaps, how we might identify life beyond our planet. In short, when thinking about life, not only do we have to consider the accepted chemistry, but also the fields that must also shape it. In effect, to fully understand life, as well as the yin of accepted particle-based chemistry, there is a yang of field-based interaction and an ethereal skeleton.
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Affiliation(s)
- Alistair V.W. Nunn
- Research Centre for Optimal Health, Department of Life Sciences, University of Westminster, London, United Kingdom.,Address correspondence to: Alistair V.W. Nunn, PhD, Research Centre for Optimal Health, Department of Life Sciences, University of Westminster, London W1W 6UW, United Kingdom
| | | | - Jimmy D. Bell
- Research Centre for Optimal Health, Department of Life Sciences, University of Westminster, London, United Kingdom
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6
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Time lapse synchrotron IR chemical imaging for observing the acclimation of a single algal cell to CO 2 treatment. Sci Rep 2021; 11:13246. [PMID: 34168226 PMCID: PMC8225881 DOI: 10.1038/s41598-021-92657-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 04/21/2021] [Indexed: 11/08/2022] Open
Abstract
Algae are the main primary producers in aquatic environments and therefore of fundamental importance for the global ecosystem. Mid-infrared (IR) microspectroscopy is a non-invasive tool that allows in principle studying chemical composition on a single-cell level. For a long time, however, mid-infrared (IR) imaging of living algal cells in an aqueous environment has been a challenge due to the strong IR absorption of water. In this study, we employed multi-beam synchrotron radiation to measure time-resolved IR hyperspectral images of individual Thalassiosira weissflogii cells in water in the course of acclimation to an abrupt change of CO2 availability (from 390 to 5000 ppm and vice versa) over 75 min. We used a previously developed algorithm to correct sinusoidal interference fringes from IR hyperspectral imaging data. After preprocessing and fringe correction of the hyperspectral data, principal component analysis (PCA) was performed to assess the spatial distribution of organic pools within the algal cells. Through the analysis of 200,000 spectra, we were able to identify compositional modifications associated with CO2 treatment. PCA revealed changes in the carbohydrate pool (1200-950 cm[Formula: see text]), lipids (1740, 2852, 2922 cm[Formula: see text]), and nucleic acid (1160 and 1201 cm[Formula: see text]) as the major response of exposure to elevated CO2 concentrations. Our results show a local metabolism response to this external perturbation.
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7
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Evers TMJ, Holt LJ, Alberti S, Mashaghi A. Reciprocal regulation of cellular mechanics and metabolism. Nat Metab 2021; 3:456-468. [PMID: 33875882 PMCID: PMC8863344 DOI: 10.1038/s42255-021-00384-w] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 03/12/2021] [Indexed: 12/12/2022]
Abstract
Metabolism and mechanics are intrinsically intertwined. External forces, sensed through the cytoskeleton or distortion of the cell and organelles, induce metabolic changes in the cell. The resulting changes in metabolism, in turn, feed back to regulate every level of cell biology, including the mechanical properties of cells and tissues. Here we examine the links between metabolism and mechanics, highlighting signalling pathways involved in the regulation and response to cellular mechanosensing. We consider how forces and metabolism regulate one another through nanoscale molecular sensors, micrometre-scale cytoskeletal networks, organelles and dynamic biomolecular condensates. Understanding this cross-talk will create diagnostic and therapeutic opportunities for metabolic disorders such as cancer, cardiovascular pathologies and obesity.
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Affiliation(s)
- Tom M J Evers
- Medical Systems Biophysics and Bioengineering, Leiden Academic Centre for Drug Research, Faculty of Science, Leiden University, Leiden, the Netherlands
| | - Liam J Holt
- Institute for Systems Genetics, New York University Langone Health, New York, NY, USA
| | - Simon Alberti
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Alireza Mashaghi
- Medical Systems Biophysics and Bioengineering, Leiden Academic Centre for Drug Research, Faculty of Science, Leiden University, Leiden, the Netherlands.
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8
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Park CK, Horton NC. Structures, functions, and mechanisms of filament forming enzymes: a renaissance of enzyme filamentation. Biophys Rev 2019; 11:927-994. [PMID: 31734826 PMCID: PMC6874960 DOI: 10.1007/s12551-019-00602-6] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 10/24/2019] [Indexed: 12/19/2022] Open
Abstract
Filament formation by non-cytoskeletal enzymes has been known for decades, yet only relatively recently has its wide-spread role in enzyme regulation and biology come to be appreciated. This comprehensive review summarizes what is known for each enzyme confirmed to form filamentous structures in vitro, and for the many that are known only to form large self-assemblies within cells. For some enzymes, studies describing both the in vitro filamentous structures and cellular self-assembly formation are also known and described. Special attention is paid to the detailed structures of each type of enzyme filament, as well as the roles the structures play in enzyme regulation and in biology. Where it is known or hypothesized, the advantages conferred by enzyme filamentation are reviewed. Finally, the similarities, differences, and comparison to the SgrAI endonuclease system are also highlighted.
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Affiliation(s)
- Chad K. Park
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721 USA
| | - Nancy C. Horton
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721 USA
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9
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Ridone P, Vassalli M, Martinac B. Piezo1 mechanosensitive channels: what are they and why are they important. Biophys Rev 2019; 11:795-805. [PMID: 31494839 PMCID: PMC6815293 DOI: 10.1007/s12551-019-00584-5] [Citation(s) in RCA: 87] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Accepted: 08/27/2019] [Indexed: 12/12/2022] Open
Abstract
Mechanosensitive (MS) ion channels are integral membrane proteins which play a crucial role in fast signaling during mechanosensory transduction processes in living cells. They are ubiquitous and old in the evolutionary sense, given their presence in cells from all three kingdoms of life found on Earth, including bacterial, archaeal, and eukaryotic organisms. As molecular transducers of mechanical force, MS channels are activated by mechanical stimuli exerted on cellular membranes, upon which they rapidly and efficiently convert these stimuli into electrical, osmotic, and/or chemical intracellular signals. Most of what we know about the gating mechanisms of MS channels comes from the work carried out on bacterial channels. However, recent progress resulting from identification and structural information of eukaryotic K2P-type TREK and TRAAK as well as Piezo1 and Piezo2 MS channels has greatly contributed to our understanding of the common biophysical principles underlying the gating mechanism and evolutionary origins of these fascinating membrane proteins. Using Piezo1 channels as an example, we briefly describe in this review what we have learned about their biophysics, physiological functions, and potential roles in "mechanopathologies."
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Affiliation(s)
- Pietro Ridone
- Mechanosensory Biophysics Laboratory, Victor Chang Cardiac Research Institute, 405 Liverpool St, Darlinghurst, NSW, 2010, Australia
- School of Biotechnology and Biomolecular Science, University of New South Wales, Kensington, NSW, 2052, Australia
| | - Massimo Vassalli
- Institute of Biophysics, National Research Council, Genoa, Italy
| | - Boris Martinac
- Mechanosensory Biophysics Laboratory, Victor Chang Cardiac Research Institute, 405 Liverpool St, Darlinghurst, NSW, 2010, Australia.
- St Vincent's Clinical School, University of New South Wales, Darlinghurst, NSW, 2010, Australia.
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10
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McCluskey GD, Bearne SL. Anfractuous assemblies of IMP dehydrogenase and CTP synthase: new twists on regulation? FEBS J 2018; 285:3724-3728. [PMID: 30285320 DOI: 10.1111/febs.14658] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 09/12/2018] [Indexed: 12/16/2022]
Abstract
CTP synthase (CTPS) and IMP dehydrogenase (IMPDH) catalyse the rate-limiting steps of de novo CTP and guanosine nucleotide biosynthesis, respectively, and form filament assemblies in response to inhibitors. A recent study explores the morphology and dynamics of these assemblies using fluorescence and super-resolution confocal microscopy with cell lines expressing CTPS1 and IMPDH2 fusion proteins. The formation and dismantling of mixed assemblies depends on nucleotide levels, suggesting a co-regulation function.
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Affiliation(s)
- Gregory D McCluskey
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Canada
| | - Stephen L Bearne
- Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Canada.,Department of Chemistry, Dalhousie University, Halifax, Canada
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11
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Atomic insights into the genesis of cellular filaments by globular proteins. Nat Struct Mol Biol 2018; 25:705-714. [PMID: 30076408 PMCID: PMC6185745 DOI: 10.1038/s41594-018-0096-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 06/21/2018] [Indexed: 02/04/2023]
Abstract
Self-assembly of proteins into filaments, such as actin and tubulin filaments, underlies essential cellular processes in all three domains of life. The early emergence of filaments in evolutionary history suggests that filament genesis might be a robust process. Here we describe the fortuitous construction of GFP fusion proteins that self-assemble as fluorescent polar filaments in Escherichia coli. Filament formation is achieved by appending as few as 12 residues. Crystal structures reveal that the protomers each donate an appendage to fill a groove between two following protomers along the filament. This exchange of appendages resembles runaway domain swapping but is distinguished by higher efficiency because monomers cannot competitively bind their own appendages. Ample evidence of this “runaway domain coupling” mechanism in nature suggests it could facilitate the evolutionary pathway from globular protein to polar filament, requiring a minimal extension of protein sequence and no significant refolding.
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12
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Park CK, Sanchez JL, Barahona C, Basantes LE, Sanchez J, Hernandez C, Horton NC. The run-on oligomer filament enzyme mechanism of SgrAI: Part 1. Assembly kinetics of the run-on oligomer filament. J Biol Chem 2018; 293:14585-14598. [PMID: 30068553 DOI: 10.1074/jbc.ra118.003680] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 07/30/2018] [Indexed: 01/06/2023] Open
Abstract
Filament or run-on oligomer formation by metabolic enzymes is now recognized as a widespread phenomenon having potentially unique enzyme regulatory properties and biological roles, and its dysfunction is implicated in human diseases such as cancer, diabetes, and developmental disorders. SgrAI is a bacterial allosteric type II restriction endonuclease that binds to invading phage DNA, may protect the host DNA from off-target cleavage activity, and forms run-on oligomeric filaments with enhanced DNA-cleavage activity and altered DNA sequence specificity. However, the mechanisms of SgrAI filament growth, cooperativity in filament formation, sequestration of enzyme activity, and advantages over other filament mechanisms remain unknown. In this first of a two-part series, we developed methods and models to derive association and dissociation rate constants of DNA-bound SgrAI in run-on oligomers and addressed the specific questions of cooperativity and filament growth mechanisms. We show that the derived rate constants are consistent with the run-on oligomer sizes determined by EM analysis and are most consistent with a noncooperative growth mode of the run-on oligomer. These models and methods are extended in the accompanying article to include the full DNA-cleavage pathway and address specific questions related to the run-on oligomer mechanism including the sequestration of DNA-cleavage activity and trapping of products.
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Affiliation(s)
- Chad K Park
- From the Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721
| | - Jonathan L Sanchez
- From the Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721
| | - Claudia Barahona
- From the Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721
| | - L Emilia Basantes
- From the Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721
| | - Juan Sanchez
- From the Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721
| | - Christian Hernandez
- From the Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721
| | - N C Horton
- From the Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721
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13
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Park CK, Sanchez JL, Barahona C, Basantes LE, Sanchez J, Hernandez C, Horton NC. The run-on oligomer filament enzyme mechanism of SgrAI: Part 2. Kinetic modeling of the full DNA cleavage pathway. J Biol Chem 2018; 293:14599-14615. [PMID: 30054273 DOI: 10.1074/jbc.ra118.003682] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 07/17/2018] [Indexed: 11/06/2022] Open
Abstract
Filament or run-on oligomer formation by enzymes is now recognized as a widespread phenomenon with potentially unique enzyme regulatory properties and biological roles. SgrAI is an allosteric type II restriction endonuclease that forms run-on oligomeric filaments with activated DNA cleavage activity and altered DNA sequence specificity. In this two-part work, we measure individual steps in the run-on oligomer filament mechanism to address specific questions of cooperativity, trapping, filament growth mechanisms, and sequestration of activity using fluorophore-labeled DNA, kinetic FRET measurements, and reaction modeling with global data fitting. The final models and rate constants show that the assembly step involving association of SgrAI-DNA complexes into the run-on oligomer filament is relatively slow (3-4 orders of magnitude slower than diffusion limited) and rate-limiting at low to moderate concentrations of SgrAI-DNA. The disassembly step involving dissociation of complexes of SgrAI-DNA from each other in the run-on oligomer filament is the next slowest step but is fast enough to limit the residence time of any one copy of SgrAI or DNA within the dynamic filament. Further, the rate constant for DNA cleavage is found to be 4 orders of magnitude faster in the run-on oligomer filament than in isolated SgrAI-DNA complexes and faster than dissociation of SgrAI-DNA complexes from the run-on oligomer filament, making the reaction efficient in that each association into the filament likely leads to DNA cleavage before filament dissociation.
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Affiliation(s)
- Chad K Park
- From the Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721
| | - Jonathan L Sanchez
- From the Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721
| | - Claudia Barahona
- From the Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721
| | - L Emilia Basantes
- From the Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721
| | - Juan Sanchez
- From the Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721
| | - Christian Hernandez
- From the Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721
| | - N C Horton
- From the Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721
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14
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Nuclear actin: ancient clue to evolution in eukaryotes? Histochem Cell Biol 2018; 150:235-244. [DOI: 10.1007/s00418-018-1693-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/29/2018] [Indexed: 12/31/2022]
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15
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Biophysical Analysis of Bacterial CTP Synthase Filaments Formed in the Presence of the Chemotherapeutic Metabolite Gemcitabine-5'-triphosphate. J Mol Biol 2018; 430:1201-1217. [PMID: 29501573 DOI: 10.1016/j.jmb.2018.02.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 02/16/2018] [Accepted: 02/23/2018] [Indexed: 11/21/2022]
Abstract
While enzyme activity is often regulated by a combination of substrate/effector availability and quaternary structure, many cytosolic enzymes may be further regulated through oligomerization into filaments. Cytidine-5'-triphosphate (CTP) synthase (CTPS) forms such filaments-a process that is promoted by the product CTP. The CTP analog and active chemotherapeutic metabolite gemcitabine-5'-triphosphate (dF-dCTP) is a potent inhibitor of CTPS; however, its effect on the enzyme's ability to form filaments is unknown. Alongside electron microscopy studies, dynamic light scattering showed that dF-dCTP induces Escherichia coli CTPS (EcCTPS) to form filaments in solution with lengths ≥30 nm in the presence of CTP or dF-dCTP. The substrate UTP blocks formation of filaments and effects their disassembly. EcCTPS variants were constructed to investigate the role of CTP-binding determinants in CTP- and dF-dCTP-dependent filament formation. Substitution of Glu 149 (i.e., E149D), which interacts with the ribose of CTP, caused reduced affinity for both CTP and dF-dCTP, and obviated filament formation. Phe 227 appears to interact with CTP through an edge-on interaction with the cytosine ring, yet the F227A and F227L variants bound CTP and dF-dCTP. F227A EcCTPS did not form filaments, while F227L EcCTPS formed shorter filaments in the presence of CTP or dF-dCTP. Hence, Phe 227 plays a role in filament formation, although replacement by a bulky hydrophobic amino acid is sufficient for limited filament formation. That dF-dCTP can induce filament formation highlights the fact that nucleotide analogs employed as chemotherapeutic agents may affect the filamentous states of enzymes and potentially alter their regulation in vivo.
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16
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Wagstaff J, Löwe J. Prokaryotic cytoskeletons: protein filaments organizing small cells. Nat Rev Microbiol 2018; 16:187-201. [PMID: 29355854 DOI: 10.1038/nrmicro.2017.153] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Most, if not all, bacterial and archaeal cells contain at least one protein filament system. Although these filament systems in some cases form structures that are very similar to eukaryotic cytoskeletons, the term 'prokaryotic cytoskeletons' is used to refer to many different kinds of protein filaments. Cytoskeletons achieve their functions through polymerization of protein monomers and the resulting ability to access length scales larger than the size of the monomer. Prokaryotic cytoskeletons are involved in many fundamental aspects of prokaryotic cell biology and have important roles in cell shape determination, cell division and nonchromosomal DNA segregation. Some of the filament-forming proteins have been classified into a small number of conserved protein families, for example, the almost ubiquitous tubulin and actin superfamilies. To understand what makes filaments special and how the cytoskeletons they form enable cells to perform essential functions, the structure and function of cytoskeletal molecules and their filaments have been investigated in diverse bacteria and archaea. In this Review, we bring these data together to highlight the diverse ways that linear protein polymers can be used to organize other molecules and structures in bacteria and archaea.
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Affiliation(s)
- James Wagstaff
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Jan Löwe
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
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17
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Uncharacterized Bacterial Structures Revealed by Electron Cryotomography. J Bacteriol 2017; 199:JB.00100-17. [PMID: 28607161 DOI: 10.1128/jb.00100-17] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 05/27/2017] [Indexed: 01/06/2023] Open
Abstract
Electron cryotomography (ECT) can reveal the native structure and arrangement of macromolecular complexes inside intact cells. This technique has greatly advanced our understanding of the ultrastructure of bacterial cells. We now view bacteria as structurally complex assemblies of macromolecular machines rather than as undifferentiated bags of enzymes. To date, our group has applied ECT to nearly 90 different bacterial species, collecting more than 15,000 cryotomograms. In addition to known structures, we have observed, to our knowledge, several uncharacterized features in these tomograms. Some are completely novel structures; others expand the features or species range of known structure types. Here, we present a survey of these uncharacterized bacterial structures in the hopes of accelerating their identification and study, and furthering our understanding of the structural complexity of bacterial cells.IMPORTANCE Bacteria are more structurally complex than is commonly appreciated. Here we present a survey of previously uncharacterized structures that we observed in bacterial cells by electron cryotomography, structures that will initiate new lines of research investigating their identities and roles.
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18
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Abstract
The organization of metabolic multienzyme complexes has been hypothesized to benefit metabolic processes and provide a coordinated way for the cell to regulate metabolism. Historically, their existence has been supported by various in vitro techniques. However, it is only recently that the existence of metabolic complexes inside living cells has come to light to corroborate this long-standing hypothesis. Indeed, subcellular compartmentalization of metabolic enzymes appears to be widespread and highly regulated. On the other hand, it is still challenging to demonstrate the functional significance of these enzyme complexes in the context of the cellular milieu. In this review, we discuss the current understanding of metabolic enzyme complexes by primarily focusing on central carbon metabolism and closely associated metabolic pathways in a variety of organisms, as well as their regulation and functional contributions to cells.
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Affiliation(s)
- Danielle L Schmitt
- Department of Chemistry and Biochemistry, University of Maryland Baltimore County (UMBC) , 1000 Hilltop Circle, Baltimore, Maryland 21250, United States
| | - Songon An
- Department of Chemistry and Biochemistry, University of Maryland Baltimore County (UMBC) , 1000 Hilltop Circle, Baltimore, Maryland 21250, United States
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19
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Chitrakar I, Kim-Holzapfel DM, Zhou W, French JB. Higher order structures in purine and pyrimidine metabolism. J Struct Biol 2017; 197:354-364. [PMID: 28115257 DOI: 10.1016/j.jsb.2017.01.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 01/14/2017] [Accepted: 01/18/2017] [Indexed: 10/20/2022]
Abstract
The recent discovery of several forms of higher order protein structures in cells has shifted the paradigm of how we think about protein organization and metabolic regulation. These dynamic and controllable protein assemblies, which are composed of dozens or hundreds of copies of an enzyme or related enzymes, have emerged as important players in myriad cellular processes. We are only beginning to appreciate the breadth of function of these types of macromolecular assemblies. These higher order structures, which can be assembled in response to varied cellular stimuli including changing metabolite concentrations or signaling cascades, give the cell the capacity to modulate levels of biomolecules both temporally and spatially. This provides an added level of control with distinct kinetics and unique features that can be harnessed as a subtle, yet powerful regulatory mechanism. Due, in large part, to advances in structural methods, such as crystallography and cryo-electron microscopy, and the advent of super-resolution microscopy techniques, a rapidly increasing number of these higher order structures are being identified and characterized. In this review, we detail what is known about the structure, function and control mechanisms of these mesoscale protein assemblies, with a particular focus on those involved in purine and pyrimidine metabolism. These structures have important implications both for our understanding of fundamental cellular processes and as fertile ground for new targets for drug discovery and development.
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Affiliation(s)
- Iva Chitrakar
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, United States
| | - Deborah M Kim-Holzapfel
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, United States
| | - Weijie Zhou
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794, United States
| | - Jarrod B French
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794, United States; Department of Chemistry, Stony Brook University, Stony Brook, NY 11794, United States.
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20
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Abstract
As discovered over the past 25 years, the cytoskeletons of bacteria and archaea are complex systems of proteins whose central components are dynamic cytomotive filaments. They perform roles in cell division, DNA partitioning, cell shape determination and the organisation of intracellular components. The protofilament structures and polymerisation activities of various actin-like, tubulin-like and ESCRT-like proteins of prokaryotes closely resemble their eukaryotic counterparts but show greater diversity. Their activities are modulated by a wide range of accessory proteins but these do not include homologues of the motor proteins that supplement filament dynamics to aid eukaryotic cell motility. Numerous other filamentous proteins, some related to eukaryotic IF-proteins/lamins and dynamins etc, seem to perform structural roles similar to those in eukaryotes.
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Affiliation(s)
- Linda A Amos
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
| | - Jan Löwe
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
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21
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Schmitt DL, Cheng YJ, Park J, An S. Sequestration-Mediated Downregulation of de Novo Purine Biosynthesis by AMPK. ACS Chem Biol 2016; 11:1917-24. [PMID: 27128383 DOI: 10.1021/acschembio.6b00039] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Dynamic partitioning of de novo purine biosynthetic enzymes into multienzyme compartments, purinosomes, has been associated with increased flux of de novo purine biosynthesis in human cells. However, we do not know of a mechanism by which de novo purine biosynthesis would be downregulated in cells. We have investigated the functional role of AMP-activated protein kinase (AMPK) in the regulation of de novo purine biosynthesis because of its regulatory action on lipid and carbohydrate biosynthetic pathways. Using pharmacological AMPK activators, we have monitored subcellular localizations of six pathway enzymes tagged with green fluorescent proteins under time-lapse fluorescence single-cell microscopy. We revealed that only one out of six pathway enzymes, formylglycinamidine ribonucleotide synthase (FGAMS), formed spatially distinct cytoplasmic granules after treatment with AMPK activators, indicating the formation of single-enzyme self-assemblies. In addition, subsequent biophysical studies using fluorescence recovery after photobleaching showed that the diffusion kinetics of FGAMS were slower when it localized inside the self-assemblies than within the purinosomes. Importantly, high-performance liquid chromatographic studies revealed that the formation of AMPK-promoted FGAMS self-assembly caused the reduction of purine metabolites in HeLa cells, indicating the downregulation of de novo purine biosynthesis. Collectively, we demonstrate here that the spatial sequestration of FGAMS by AMPK is a mechanism by which de novo purine biosynthesis is downregulated in human cells.
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Affiliation(s)
- Danielle L. Schmitt
- Department of Chemistry and Biochemistry, ‡Department of Mathematics and Statistics, University of Maryland Baltimore County (UMBC), 1000 Hilltop Circle, Baltimore, Maryland 21250, United States
| | - Yun-ju Cheng
- Department of Chemistry and Biochemistry, ‡Department of Mathematics and Statistics, University of Maryland Baltimore County (UMBC), 1000 Hilltop Circle, Baltimore, Maryland 21250, United States
| | - Junyong Park
- Department of Chemistry and Biochemistry, ‡Department of Mathematics and Statistics, University of Maryland Baltimore County (UMBC), 1000 Hilltop Circle, Baltimore, Maryland 21250, United States
| | - Songon An
- Department of Chemistry and Biochemistry, ‡Department of Mathematics and Statistics, University of Maryland Baltimore County (UMBC), 1000 Hilltop Circle, Baltimore, Maryland 21250, United States
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22
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Abstract
Determining the mechanisms of enzymatic regulation is central to the study of cellular metabolism. Regulation of enzyme activity via polymerization-mediated strategies has been shown to be widespread, and plays a vital role in mediating cellular homeostasis. In this review, we begin with an overview of the filamentation of CTP synthase, which forms filamentous structures termed cytoophidia. We then highlight other important examples of the phenomenon. Moreover, we discuss recent data relating to the regulation of enzyme activity by compartmentalization into cytoophidia. Finally, we hypothesize potential roles for enzyme filament formation in the regulation of metabolism, development and disease.
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Affiliation(s)
- Gabriel N Aughey
- a MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics , University of Oxford , Oxford , UK
| | - Ji-Long Liu
- a MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics , University of Oxford , Oxford , UK
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23
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Oikonomou CM, Chang YW, Jensen GJ. A new view into prokaryotic cell biology from electron cryotomography. Nat Rev Microbiol 2016; 14:205-20. [PMID: 26923112 PMCID: PMC5551487 DOI: 10.1038/nrmicro.2016.7] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Electron cryotomography (ECT) enables intact cells to be visualized in 3D in an essentially native state to 'macromolecular' (∼4 nm) resolution, revealing the basic architectures of complete nanomachines and their arrangements in situ. Since its inception, ECT has advanced our understanding of many aspects of prokaryotic cell biology, from morphogenesis to subcellular compartmentalization and from metabolism to complex interspecies interactions. In this Review, we highlight how ECT has provided structural and mechanistic insights into the physiology of bacteria and archaea and discuss prospects for the future.
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Affiliation(s)
- Catherine M Oikonomou
- Howard Hughes Medical Institute; Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125, USA
| | - Yi-Wei Chang
- Howard Hughes Medical Institute; Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125, USA
| | - Grant J Jensen
- Howard Hughes Medical Institute; Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125, USA
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24
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Abstract
All life demands the temporal and spatial control of essential biological functions. In bacteria, the recent discovery of coordinating elements provides a framework to begin to explain cell growth and division. Here we present the discovery of a supramolecular structure in the membrane of the coccal bacterium Staphylococcus aureus, which leads to the formation of a large-scale pattern across the entire cell body; this has been unveiled by studying the distribution of essential proteins involved in lipid metabolism (PlsY and CdsA). The organization is found to require MreD, which determines morphology in rod-shaped cells. The distribution of protein complexes can be explained as a spontaneous pattern formation arising from the competition between the energy cost of bending that they impose on the membrane, their entropy of mixing, and the geometric constraints in the system. Our results provide evidence for the existence of a self-organized and nonpercolating molecular scaffold involving MreD as an organizer for optimal cell function and growth based on the intrinsic self-assembling properties of biological molecules.
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25
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Gunning PW, Ghoshdastider U, Whitaker S, Popp D, Robinson RC. The evolution of compositionally and functionally distinct actin filaments. J Cell Sci 2015; 128:2009-19. [DOI: 10.1242/jcs.165563] [Citation(s) in RCA: 157] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
ABSTRACT
The actin filament is astonishingly well conserved across a diverse set of eukaryotic species. It has essentially remained unchanged in the billion years that separate yeast, Arabidopsis and man. In contrast, bacterial actin-like proteins have diverged to the extreme, and many of them are not readily identified from sequence-based homology searches. Here, we present phylogenetic analyses that point to an evolutionary drive to diversify actin filament composition across kingdoms. Bacteria use a one-filament-one-function system to create distinct filament systems within a single cell. In contrast, eukaryotic actin is a universal force provider in a wide range of processes. In plants, there has been an expansion of the number of closely related actin genes, whereas in fungi and metazoa diversification in tropomyosins has increased the compositional variety in actin filament systems. Both mechanisms dictate the subset of actin-binding proteins that interact with each filament type, leading to specialization in function. In this Hypothesis, we thus propose that different mechanisms were selected in bacteria, plants and metazoa, which achieved actin filament compositional variation leading to the expansion of their functional diversity.
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Affiliation(s)
- Peter W. Gunning
- School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Umesh Ghoshdastider
- Institute of Molecular and Cell Biology, A*STAR (Agency for Science, Technology and Research), Biopolis, Singapore 138673
| | - Shane Whitaker
- School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - David Popp
- Institute of Molecular and Cell Biology, A*STAR (Agency for Science, Technology and Research), Biopolis, Singapore 138673
| | - Robert C. Robinson
- Institute of Molecular and Cell Biology, A*STAR (Agency for Science, Technology and Research), Biopolis, Singapore 138673
- Department of Biochemistry, National University of Singapore, 8 Medical Drive, Singapore 117597
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26
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Shah S, Sanchez J, Stewart A, Piperakis MM, Cosstick R, Nichols C, Park CK, Ma X, Wysocki V, Bitinaite J, Horton NC. Probing the run-on oligomer of activated SgrAI bound to DNA. PLoS One 2015; 10:e0124783. [PMID: 25880668 PMCID: PMC4399878 DOI: 10.1371/journal.pone.0124783] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2015] [Accepted: 03/05/2015] [Indexed: 02/04/2023] Open
Abstract
SgrAI is a type II restriction endonuclease with an unusual mechanism of activation involving run-on oligomerization. The run-on oligomer is formed from complexes of SgrAI bound to DNA containing its 8 bp primary recognition sequence (uncleaved or cleaved), and also binds (and thereby activates for DNA cleavage) complexes of SgrAI bound to secondary site DNA sequences which contain a single base substitution in either the 1st/8th or the 2nd/7th position of the primary recognition sequence. This modulation of enzyme activity via run-on oligomerization is a newly appreciated phenomenon that has been shown for a small but increasing number of enzymes. One outstanding question regarding the mechanistic model for SgrAI is whether or not the activating primary site DNA must be cleaved by SgrAI prior to inducing activation. Herein we show that an uncleavable primary site DNA containing a 3'-S-phosphorothiolate is in fact able to induce activation. In addition, we now show that cleavage of secondary site DNA can be activated to nearly the same degree as primary, provided a sufficient number of flanking base pairs are present. We also show differences in activation and cleavage of the two types of secondary site, and that effects of selected single site substitutions in SgrAI, as well as measured collisional cross-sections from previous work, are consistent with the cryo-electron microscopy model for the run-on activated oligomer of SgrAI bound to DNA.
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Affiliation(s)
- Santosh Shah
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, United States of America
| | - Jonathan Sanchez
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, United States of America
| | - Andrew Stewart
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, United States of America
- Genetics Graduate Program, University of Arizona, Tucson, AZ 85721, United States of America
| | - Michael M. Piperakis
- Department of Chemistry, University of Liverpool, Liverpool, United Kingdom, L69 7ZD, United States of America
| | - Richard Cosstick
- Department of Chemistry, University of Liverpool, Liverpool, United Kingdom, L69 7ZD, United States of America
| | - Claire Nichols
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, United States of America
| | - Chad K. Park
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, United States of America
| | - Xin Ma
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, United States of America
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH 43210, United States of America
| | - Vicki Wysocki
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, United States of America
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH 43210, United States of America
| | - Jurate Bitinaite
- New England Biolabs, Inc., 240 County Road, Ipswich, MA 01938, United States of America
| | - Nancy C. Horton
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, United States of America
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27
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Vaitheesvaran B, Hartil K, Navare A, Zheng, ÓBroin P, Golden A, Guha, Lee WN, Kurland I, Bruce JE. Role of the tumor suppressor IQGAP2 in metabolic homeostasis: Possible link between diabetes and cancer. Metabolomics 2014; 10:920-937. [PMID: 25254002 PMCID: PMC4169985 DOI: 10.1007/s11306-014-0639-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Deficiency of IQGAP2, a scaffolding protein expressed primarily in liver leads to rearrangements of hepatic protein compartmentalization and altered regulation of enzyme functions predisposing development of hepatocellular carcinoma and diabetes. Employing a systems approach with proteomics, metabolomics and fluxes characterizations, we examined the effects of IQGAP2 deficient proteomic changes on cellular metabolism and the overall metabolic phenotype. Iqgap2-/- mice demonstrated metabolic inflexibility, fasting hyperglycemia and obesity. Such phenotypic characteristics were associated with aberrant hepatic regulations of glycolysis/gluconeogenesis, glycogenolysis, lipid homeostasis and futile cycling corroborated with corresponding proteomic changes in cytosolic and mitochondrial compartments. IQGAP2 deficiency also led to truncated TCA-cycle, increased anaplerosis, increased supply of acetyl-CoA for de novo lipogenesis, and increased mitochondrial methyl-donor metabolism necessary for nucleotides synthesis. Our results suggest that changes in metabolic networks in IQGAP2 deficiency create a hepatic environment of a 'pre-diabetic' phenotype and a predisposition to non-alcoholic fatty liver disease (NAFLD) which has been linked to the development of hepatocellular carcinoma.
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Affiliation(s)
- B. Vaitheesvaran
- Department of Medicine, Diabetes Center, Stable Isotope and Metabolomics Core Facility, Albert Einstein College of Medicine, Bronx, New York, 10461
| | - K. Hartil
- Department of Medicine, Diabetes Center, Stable Isotope and Metabolomics Core Facility, Albert Einstein College of Medicine, Bronx, New York, 10461
| | - A. Navare
- Department of Genome Sciences, University of Washington, Seattle, Washington, 98109
| | - Zheng
- Department of Genome Sciences, University of Washington, Seattle, Washington, 98109
| | - P. ÓBroin
- Department of Medicine, Diabetes Center, Stable Isotope and Metabolomics Core Facility, Albert Einstein College of Medicine, Bronx, New York, 10461
- Department of Genetics., Division of Computational Genetics, Albert Einstein College of Medicine, Bronx, NewYork, 10461
| | - A. Golden
- Department of Genetics., Division of Computational Genetics, Albert Einstein College of Medicine, Bronx, NewYork, 10461
| | - Guha
- Department of Radiation Oncology, Albert Einstein College of Medicine, Bronx, New York, 10461
| | - WN. Lee
- Department of Pediatrics, Division of Endocrinology and Metabolism, University of California, Los Angeles, California 90502
| | - I.J Kurland
- Department of Medicine, Diabetes Center, Stable Isotope and Metabolomics Core Facility, Albert Einstein College of Medicine, Bronx, New York, 10461
| | - J. E. Bruce
- Department of Genome Sciences, University of Washington, Seattle, Washington, 98109
- Corresponding author: James E. Bruce. Department of Genome Sciences, University of Washington, Seattle, Washington, 98109., , Phone: 206-543-0220, Fax: 206-616-0008
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28
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Jékely G. Origin and evolution of the self-organizing cytoskeleton in the network of eukaryotic organelles. Cold Spring Harb Perspect Biol 2014; 6:a016030. [PMID: 25183829 DOI: 10.1101/cshperspect.a016030] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The eukaryotic cytoskeleton evolved from prokaryotic cytomotive filaments. Prokaryotic filament systems show bewildering structural and dynamic complexity and, in many aspects, prefigure the self-organizing properties of the eukaryotic cytoskeleton. Here, the dynamic properties of the prokaryotic and eukaryotic cytoskeleton are compared, and how these relate to function and evolution of organellar networks is discussed. The evolution of new aspects of filament dynamics in eukaryotes, including severing and branching, and the advent of molecular motors converted the eukaryotic cytoskeleton into a self-organizing "active gel," the dynamics of which can only be described with computational models. Advances in modeling and comparative genomics hold promise of a better understanding of the evolution of the self-organizing cytoskeleton in early eukaryotes, and its role in the evolution of novel eukaryotic functions, such as amoeboid motility, mitosis, and ciliary swimming.
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Affiliation(s)
- Gáspár Jékely
- Max Planck Institute for Developmental Biology, 72076 Tuebingen, Germany
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29
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Barry RM, Bitbol AF, Lorestani A, Charles EJ, Habrian CH, Hansen JM, Li HJ, Baldwin EP, Wingreen NS, Kollman JM, Gitai Z. Large-scale filament formation inhibits the activity of CTP synthetase. eLife 2014; 3:e03638. [PMID: 25030911 PMCID: PMC4126345 DOI: 10.7554/elife.03638] [Citation(s) in RCA: 122] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
CTP Synthetase (CtpS) is a universally conserved and essential metabolic enzyme. While many enzymes form small oligomers, CtpS forms large-scale filamentous structures of unknown function in prokaryotes and eukaryotes. By simultaneously monitoring CtpS polymerization and enzymatic activity, we show that polymerization inhibits activity, and CtpS's product, CTP, induces assembly. To understand how assembly inhibits activity, we used electron microscopy to define the structure of CtpS polymers. This structure suggests that polymerization sterically hinders a conformational change necessary for CtpS activity. Structure-guided mutagenesis and mathematical modeling further indicate that coupling activity to polymerization promotes cooperative catalytic regulation. This previously uncharacterized regulatory mechanism is important for cellular function since a mutant that disrupts CtpS polymerization disrupts E. coli growth and metabolic regulation without reducing CTP levels. We propose that regulation by large-scale polymerization enables ultrasensitive control of enzymatic activity while storing an enzyme subpopulation in a conformationally restricted form that is readily activatable. DOI:http://dx.doi.org/10.7554/eLife.03638.001 Enzymes are proteins that perform reactions that can convert one or more chemicals (the substrates) into others (the products). The rate at which an enzyme produces its product is often carefully regulated. Some molecules slow or stop an enzyme by binding to and blocking the site where its substrates normally bind: its ‘active site’. Other molecules can also bind to sites other than the active site, which can cause the enzyme to become either more or less active. Almost all living things have an enzyme called CTP synthetase that makes one of the building blocks that is used to build DNA and a similar molecule called RNA. This enzyme converts a molecule called uridine triphosphate (or UTP) into another called cytidine triphosphate (CTP): a reaction that is powered by breaking down molecules of adenosine triphosphate (ATP). The amount of CTP synthetase made by a cell is carefully controlled. The enzyme's activity is also regulated by the levels of UTP and CTP, and by another molecule (called GTP) that binds to a site outside of its active site. Four copies of the CTP synthetase protein must work together before this enzyme can turn UTP into CTP. The enzyme also forms much larger aggregates, or polymers; however, it is not clear what causes these polymers to form, or what they do in a cell. Barry et al. have now discovered that CTP synthetase is almost completely inactivated when these polymers are formed. Furthermore, CTP encourages the polymers to form, whilst UTP and ATP cause them to disassemble. Therefore, this enzyme is least active when there is excess product in the cell, and most active when its substrates are plentiful. By determining the three-dimensional structure of a CTP synthetase polymer, Barry et al. reveal that although CTP is bound to the enzymes, their active sites are still freely accessible. However, the enzymes in the polymer appear to be locked into a shape that makes them unable to carry out their function. When Barry et al. then mutated the enzyme so that it was unable to form polymers it was also no longer inactivated in the same way by CTP. Bacterial cells with only these mutant versions of CTP synthetase are unable to properly control their levels of CTP. This suggests that polymer formation is important for regulating this enzyme in response to a build up of its product. Further work is needed to see whether the regulation of CTP synthetase activity by forming polymers is specific to this enzyme or a widespread mechanism that is used to control other enzymes too. DOI:http://dx.doi.org/10.7554/eLife.03638.002
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Affiliation(s)
- Rachael M Barry
- Department of Molecular Biology, Princeton University, Princeton, United States
| | - Anne-Florence Bitbol
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, United States
| | - Alexander Lorestani
- Department of Molecular Biology, Princeton University, Princeton, United States
| | - Emeric J Charles
- Department of Anatomy and Cell Biology, McGill University, Montreal, Canada
| | - Chris H Habrian
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, United States
| | - Jesse M Hansen
- Department of Anatomy and Cell Biology, McGill University, Montreal, Canada
| | - Hsin-Jung Li
- Department of Molecular Biology, Princeton University, Princeton, United States
| | - Enoch P Baldwin
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, United States
| | - Ned S Wingreen
- Department of Molecular Biology, Princeton University, Princeton, United States Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, United States
| | - Justin M Kollman
- Department of Anatomy and Cell Biology, McGill University, Montreal, Canada Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montreal, Canada
| | - Zemer Gitai
- Department of Molecular Biology, Princeton University, Princeton, United States
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30
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Petrovska I, Nüske E, Munder MC, Kulasegaran G, Malinovska L, Kroschwald S, Richter D, Fahmy K, Gibson K, Verbavatz JM, Alberti S. Filament formation by metabolic enzymes is a specific adaptation to an advanced state of cellular starvation. eLife 2014; 3:eLife.02409. [PMID: 24771766 PMCID: PMC4011332 DOI: 10.7554/elife.02409] [Citation(s) in RCA: 160] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 04/10/2014] [Indexed: 01/20/2023] Open
Abstract
One of the key questions in biology is how the metabolism of a cell responds to changes in the environment. In budding yeast, starvation causes a drop in intracellular pH, but the functional role of this pH change is not well understood. Here, we show that the enzyme glutamine synthetase (Gln1) forms filaments at low pH and that filament formation leads to enzymatic inactivation. Filament formation by Gln1 is a highly cooperative process, strongly dependent on macromolecular crowding, and involves back-to-back stacking of cylindrical homo-decamers into filaments that associate laterally to form higher order fibrils. Other metabolic enzymes also assemble into filaments at low pH. Hence, we propose that filament formation is a general mechanism to inactivate and store key metabolic enzymes during a state of advanced cellular starvation. These findings have broad implications for understanding the interplay between nutritional stress, the metabolism and the physical organization of a cell.
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Affiliation(s)
- Ivana Petrovska
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Elisabeth Nüske
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Matthias C Munder
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | | | - Liliana Malinovska
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Sonja Kroschwald
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Doris Richter
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Karim Fahmy
- Institute of Resource Ecology, Helmholtz Institute Dresden-Rossendorf, Dresden, Germany
| | - Kimberley Gibson
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Jean-Marc Verbavatz
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Simon Alberti
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
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31
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Bush MJ, Bibb MJ, Chandra G, Findlay KC, Buttner MJ. Genes required for aerial growth, cell division, and chromosome segregation are targets of WhiA before sporulation in Streptomyces venezuelae. mBio 2013; 4:e00684-13. [PMID: 24065632 PMCID: PMC3781837 DOI: 10.1128/mbio.00684-13] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 08/23/2013] [Indexed: 01/12/2023] Open
Abstract
UNLABELLED WhiA is a highly unusual transcriptional regulator related to a family of eukaryotic homing endonucleases. WhiA is required for sporulation in the filamentous bacterium Streptomyces, but WhiA homologues of unknown function are also found throughout the Gram-positive bacteria. To better understand the role of WhiA in Streptomyces development and its function as a transcription factor, we identified the WhiA regulon through a combination of chromatin immunoprecipitation-sequencing (ChIP-seq) and microarray transcriptional profiling, exploiting a new model organism for the genus, Streptomyces venezuelae, which sporulates in liquid culture. The regulon encompasses ~240 transcription units, and WhiA appears to function almost equally as an activator and as a repressor. Bioinformatic analysis of the upstream regions of the complete regulon, combined with DNase I footprinting, identified a short but highly conserved asymmetric sequence, GACAC, associated with the majority of WhiA targets. Construction of a null mutant showed that whiA is required for the initiation of sporulation septation and chromosome segregation in S. venezuelae, and several genes encoding key proteins of the Streptomyces cell division machinery, such as ftsZ, ftsW, and ftsK, were found to be directly activated by WhiA during development. Several other genes encoding proteins with important roles in development were also identified as WhiA targets, including the sporulation-specific sigma factor σ(WhiG) and the diguanylate cyclase CdgB. Cell division is tightly coordinated with the orderly arrest of apical growth in the sporogenic cell, and filP, encoding a key component of the polarisome that directs apical growth, is a direct target for WhiA-mediated repression during sporulation. IMPORTANCE Since the initial identification of the genetic loci required for Streptomyces development, all of the bld and whi developmental master regulators have been cloned and characterized, and significant progress has been made toward understanding the cell biological processes that drive morphogenesis. A major challenge now is to connect the cell biological processes and the developmental master regulators by dissecting the regulatory networks that link the two. Studies of these regulatory networks have been greatly facilitated by the recent introduction of Streptomyces venezuelae as a new model system for the genus, a species that sporulates in liquid culture. Taking advantage of S. venezuelae, we have characterized the regulon of genes directly under the control of one of these master regulators, WhiA. Our results implicate WhiA in the direct regulation of key steps in sporulation, including the cessation of aerial growth, the initiation of cell division, and chromosome segregation.
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Affiliation(s)
- Matthew J Bush
- Department of Molecular Microbiology, John Innes Centre, Norwich, United Kingdom.
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32
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Saier MH. Microcompartments and protein machines in prokaryotes. J Mol Microbiol Biotechnol 2013; 23:243-69. [PMID: 23920489 DOI: 10.1159/000351625] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The prokaryotic cell was once thought of as a 'bag of enzymes' with little or no intracellular compartmentalization. In this view, most reactions essential for life occurred as a consequence of random molecular collisions involving substrates, cofactors and cytoplasmic enzymes. Our current conception of a prokaryote is far from this view. We now consider a bacterium or an archaeon as a highly structured, nonrandom collection of functional membrane-embedded and proteinaceous molecular machines, each of which serves a specialized function. In this article we shall present an overview of such microcompartments including (1) the bacterial cytoskeleton and the apparati allowing DNA segregation during cell division; (2) energy transduction apparati involving light-driven proton pumping and ion gradient-driven ATP synthesis; (3) prokaryotic motility and taxis machines that mediate cell movements in response to gradients of chemicals and physical forces; (4) machines of protein folding, secretion and degradation; (5) metabolosomes carrying out specific chemical reactions; (6) 24-hour clocks allowing bacteria to coordinate their metabolic activities with the daily solar cycle, and (7) proteinaceous membrane compartmentalized structures such as sulfur granules and gas vacuoles. Membrane-bound prokaryotic organelles were considered in a recent Journal of Molecular Microbiology and Biotechnology written symposium concerned with membranous compartmentalization in bacteria [J Mol Microbiol Biotechnol 2013;23:1-192]. By contrast, in this symposium, we focus on proteinaceous microcompartments. These two symposia, taken together, provide the interested reader with an objective view of the remarkable complexity of what was once thought of as a simple noncompartmentalized cell.
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Affiliation(s)
- Milton H Saier
- Division of Biological Sciences, Department of Molecular Biology, University of California at San Diego, La Jolla, Calif. 92093-0116, USA.
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33
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Reimold C, Defeu Soufo HJ, Dempwolff F, Graumann PL. Motion of variable-length MreB filaments at the bacterial cell membrane influences cell morphology. Mol Biol Cell 2013; 24:2340-9. [PMID: 23783036 PMCID: PMC3727927 DOI: 10.1091/mbc.e12-10-0728] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Revised: 06/04/2013] [Accepted: 06/07/2013] [Indexed: 01/09/2023] Open
Abstract
The maintenance of rod-cell shape in many bacteria depends on actin-like MreB proteins and several membrane proteins that interact with MreB. Using superresolution microscopy, we show that at 50-nm resolution, Bacillus subtilis MreB forms filamentous structures of length up to 3.4 μm underneath the cell membrane, which run at angles diverging up to 40° relative to the cell circumference. MreB from Escherichia coli forms at least 1.4-μm-long filaments. MreB filaments move along various tracks with a maximal speed of 85 nm/s, and the loss of ATPase activity leads to the formation of extended and static filaments. Suboptimal growth conditions lead to formation of patch-like structures rather than extended filaments. Coexpression of wild-type MreB with MreB mutated in the subunit interface leads to formation of shorter MreB filaments and a strong effect on cell shape, revealing a link between filament length and cell morphology. Thus MreB has an extended-filament architecture with the potential to position membrane proteins over long distances, whose localization in turn may affect the shape of the cell wall.
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Affiliation(s)
- Christian Reimold
- Mikrobiologie, Fakultät für Biologie, Universität Freiburg, 79104 Freiburg, Germany
| | | | - Felix Dempwolff
- SYNMIKRO, LOEWE-Zentrum für Synthetische Mikrobiologie, 35043 Marburg, Germany
| | - Peter L. Graumann
- Mikrobiologie, Fakultät für Biologie, Universität Freiburg, 79104 Freiburg, Germany
- SYNMIKRO, LOEWE-Zentrum für Synthetische Mikrobiologie, 35043 Marburg, Germany
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34
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Role of polyphosphate in thermophilic Synechococcus sp. from microbial mats. J Bacteriol 2013; 195:3309-19. [PMID: 23687278 DOI: 10.1128/jb.00207-13] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Synechococcus OS-B', a thermophilic unicellular cyanobacterium, recently isolated from the microbial mats in Octopus Spring (Yellowstone National Park), induces a suite of genes, including phosphatases and transporters, in response to phosphorus (P) starvation. Here we describe two different approaches to examine the ability of Synechococcus OS-B' to synthesize and break down polyphosphate (poly P), a key storage compound in many prokaryotes. First, we developed a transformation protocol to create mutants in the polyphosphate kinase (ppk), the major enzyme responsible for the synthesis of poly P. The ppk mutant exhibited a pleiotropic phenotype with defects in poly P accumulation, aberrant levels of Pho regulon transcripts, growth defects, and changes in cell size and exopolysaccharide levels, among others. Second, we measured transcripts of ppk and ppx (encoding the polyphosphatase) directly from mat samples and found that the levels varied dramatically over a diel cycle. We also used Western blot analysis to quantify levels of PPK and PPX and found that these enzymes differentially accumulated during the diel cycle. Levels of polyphosphate kinase peaked at night, while polyphosphatase levels were highest during the early morning hours. We hypothesize that the opposing activities of these two enzymes allow cells to store and utilize poly P to optimize growth over a diel cycle.
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35
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Ludueña RF. A Hypothesis on the Origin and Evolution of Tubulin. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 302:41-185. [DOI: 10.1016/b978-0-12-407699-0.00002-9] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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36
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Marshall WF, Young KD, Swaffer M, Wood E, Nurse P, Kimura A, Frankel J, Wallingford J, Walbot V, Qu X, Roeder AHK. What determines cell size? BMC Biol 2012; 10:101. [PMID: 23241366 PMCID: PMC3522064 DOI: 10.1186/1741-7007-10-101] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2012] [Accepted: 12/12/2012] [Indexed: 11/16/2022] Open
Affiliation(s)
- Wallace F Marshall
- Department of Biochemistry and Biophysics, Center for Systems and Synthetic Biology, University of California, San Francisco, 600 16th St, San Francisco, CA 94158, USA
| | - Kevin D Young
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Matthew Swaffer
- Cell Cycle Lab, Cancer Research UK, London Research Institute, 44 Lincoln's Inn Fields, London, WC2A 3LY, UK
| | - Elizabeth Wood
- Cell Cycle Lab, Cancer Research UK, London Research Institute, 44 Lincoln's Inn Fields, London, WC2A 3LY, UK
| | - Paul Nurse
- Cell Cycle Lab, Cancer Research UK, London Research Institute, 44 Lincoln's Inn Fields, London, WC2A 3LY, UK
- Laboratory of Yeast Genetics and Biology, The Rockeller University, 1230 York Avenue, New York, NY 10065, USA
- The Francis Crick Institute, Euston Road 215, London, NW1 2BE, UK
| | - Akatsuki Kimura
- Cell Architecture Laboratory, Structural Biology Center, National Institute of Genetics, Yata 1111, Mishima, Shizuoka 411-8540, Japan
| | - Joseph Frankel
- Department of Biology, University of Iowa, 129 E. Jefferson Street, Iowa City, IA 52242, USA
| | - John Wallingford
- HHMI & Molecular Cell and Developmental Biology, University of Texas, Austin, 78712, USA
| | - Virginia Walbot
- Virginia WalbotDepartment of Biology, Stanford University, Stanford, CA 72205, USA
| | - Xian Qu
- Xian Qu, Cornell University, 244 Weill Hall, 526 Campus Rd, Ithaca, NY 14853, USA
| | - Adrienne HK Roeder
- Cornell University, 239 Weill Hall, 526 Campus Rd, Ithaca, NY 14853, USA
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37
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Abstract
Far from being simple 'bags' of enzymes, bacteria are richly endowed with ultrastructures that challenge and expand standard definitions of the cytoskeleton. Here we review rods, rings, twisted pairs, tubes, sheets, spirals, moving patches, meshes and composites, and suggest defining the term 'bacterial cytoskeleton' as all cytoplasmic protein filaments and their superstructures that move or scaffold (stabilize/position/recruit) other cellular materials. The evolution of each superstructure has been driven by specific functional requirements. As a result, while homologous proteins with different functions have evolved to form surprisingly divergent superstructures, those of unrelated proteins with similar functions have converged.
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Affiliation(s)
- Martin Pilhofer
- Howard Hughes Medical Institute and Division of Biology, California Institute of Technology, 1200 E California Blvd, M/C 114-96, Pasadena, CA, USA.
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38
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Ingerson-Mahar M, Gitai Z. A growing family: the expanding universe of the bacterial cytoskeleton. FEMS Microbiol Rev 2011; 36:256-66. [PMID: 22092065 DOI: 10.1111/j.1574-6976.2011.00316.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 11/02/2011] [Accepted: 11/10/2011] [Indexed: 12/16/2022] Open
Abstract
Cytoskeletal proteins are important mediators of cellular organization in both eukaryotes and bacteria. In the past, cytoskeletal studies have largely focused on three major cytoskeletal families, namely the eukaryotic actin, tubulin, and intermediate filament (IF) proteins and their bacterial homologs MreB, FtsZ, and crescentin. However, mounting evidence suggests that these proteins represent only the tip of the iceberg, as the cellular cytoskeletal network is far more complex. In bacteria, each of MreB, FtsZ, and crescentin represents only one member of large families of diverse homologs. There are also newly identified bacterial cytoskeletal proteins with no eukaryotic homologs, such as WACA proteins and bactofilins. Furthermore, there are universally conserved proteins, such as the metabolic enzyme CtpS, that assemble into filamentous structures that can be repurposed for structural cytoskeletal functions. Recent studies have also identified an increasing number of eukaryotic cytoskeletal proteins that are unrelated to actin, tubulin, and IFs, such that expanding our understanding of cytoskeletal proteins is advancing the understanding of the cell biology of all organisms. Here, we summarize the recent explosion in the identification of new members of the bacterial cytoskeleton and describe a hypothesis for the evolution of the cytoskeleton from self-assembling enzymes.
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