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Bell PJL. Eukaryogenesis: The Rise of an Emergent Superorganism. Front Microbiol 2022; 13:858064. [PMID: 35633668 PMCID: PMC9130767 DOI: 10.3389/fmicb.2022.858064] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 04/15/2022] [Indexed: 12/11/2022] Open
Abstract
Although it is widely taught that all modern life descended via modification from a last universal common ancestor (LUCA), this dominant paradigm is yet to provide a generally accepted explanation for the chasm in design between prokaryotic and eukaryotic cells. Counter to this dominant paradigm, the viral eukaryogenesis (VE) hypothesis proposes that the eukaryotes originated as an emergent superorganism and thus did not evolve from LUCA via descent with incremental modification. According to the VE hypothesis, the eukaryotic nucleus descends from a viral factory, the mitochondrion descends from an enslaved alpha-proteobacteria and the cytoplasm and plasma membrane descend from an archaeal host. A virus initiated the eukaryogenesis process by colonising an archaeal host to create a virocell that had its metabolism reprogrammed to support the viral factory. Subsequently, viral processes facilitated the entry of a bacterium into the archaeal cytoplasm which was also eventually reprogrammed to support the viral factory. As the viral factory increased control of the consortium, the archaeal genome was lost, the bacterial genome was greatly reduced and the viral factory eventually evolved into the nucleus. It is proposed that the interaction between these three simple components generated a superorganism whose emergent properties allowed the evolution of eukaryotic complexity. If the radical tenets of the VE hypothesis are ultimately accepted, current biological paradigms regarding viruses, cell theory, LUCA and the universal Tree of Life (ToL) should be fundamentally altered or completely abandoned.
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Mishra D, Srinivasan R. Catching a Walker in the Act-DNA Partitioning by ParA Family of Proteins. Front Microbiol 2022; 13:856547. [PMID: 35694299 PMCID: PMC9178275 DOI: 10.3389/fmicb.2022.856547] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 04/28/2022] [Indexed: 12/01/2022] Open
Abstract
Partitioning the replicated genetic material is a crucial process in the cell cycle program of any life form. In bacteria, many plasmids utilize cytoskeletal proteins that include ParM and TubZ, the ancestors of the eukaryotic actin and tubulin, respectively, to segregate the plasmids into the daughter cells. Another distinct class of cytoskeletal proteins, known as the Walker A type Cytoskeletal ATPases (WACA), is unique to Bacteria and Archaea. ParA, a WACA family protein, is involved in DNA partitioning and is more widespread. A centromere-like sequence parS, in the DNA is bound by ParB, an adaptor protein with CTPase activity to form the segregation complex. The ParA ATPase, interacts with the segregation complex and partitions the DNA into the daughter cells. Furthermore, the Walker A motif-containing ParA superfamily of proteins is associated with a diverse set of functions ranging from DNA segregation to cell division, cell polarity, chemotaxis cluster assembly, cellulose biosynthesis and carboxysome maintenance. Unifying principles underlying the varied range of cellular roles in which the ParA superfamily of proteins function are outlined. Here, we provide an overview of the recent findings on the structure and function of the ParB adaptor protein and review the current models and mechanisms by which the ParA family of proteins function in the partitioning of the replicated DNA into the newly born daughter cells.
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Affiliation(s)
- Dipika Mishra
- School of Biological Sciences, National Institute of Science Education and Research, Bhubaneswar, India
- Homi Bhabha National Institutes, Mumbai, India
| | - Ramanujam Srinivasan
- School of Biological Sciences, National Institute of Science Education and Research, Bhubaneswar, India
- Homi Bhabha National Institutes, Mumbai, India
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3
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Ramos-León F, Ramamurthi K. Cytoskeletal proteins: Lessons learned from bacteria. Phys Biol 2022; 19. [PMID: 35081523 DOI: 10.1088/1478-3975/ac4ef0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 01/26/2022] [Indexed: 11/11/2022]
Abstract
Cytoskeletal proteins are classified as a group that is defined functionally, whose members are capable of polymerizing into higher order structures, either dynamically or statically, to perform structural roles during a variety of cellular processes. In eukaryotes, the most well-studied cytoskeletal proteins are actin, tubulin, and intermediate filaments, and are essential for cell shape and movement, chromosome segregation, and intracellular cargo transport. Prokaryotes often harbor homologs of these proteins, but in bacterial cells, these homologs are usually not employed in roles that can be strictly defined as "cytoskeletal". However, several bacteria encode other proteins capable of polymerizing which, although they do not appear to have a eukaryotic counterpart, nonetheless appear to perform a more traditional "cytoskeletal" function. In this review, we discuss recent reports that cover the structure and functions of prokaryotic proteins that are broadly termed as cytoskeletal, either by sequence homology or by function, to highlight how the enzymatic properties of traditionally studied cytoskeletal proteins may be used for other types of cellular functions; and to demonstrate how truly "cytoskeletal" functions may be performed by uniquely bacterial proteins that do not display homology to eukaryotic proteins.
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Affiliation(s)
- Félix Ramos-León
- National Institutes of Health, 37 Convent Dr., Bldg 37, Room 5132, Bethesda, Maryland, 20892, UNITED STATES
| | - Kumaran Ramamurthi
- Laboratory of Molecular Biology, National Cancer Institute, 37 Convent Dr, Bldg 37, Room 5132, Bethesda, Maryland, 20892, UNITED STATES
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4
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Unveiling Ecological and Genetic Novelty within Lytic and Lysogenic Viral Communities of Hot Spring Phototrophic Microbial Mats. Microbiol Spectr 2021; 9:e0069421. [PMID: 34787442 PMCID: PMC8597652 DOI: 10.1128/spectrum.00694-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Viruses exert diverse ecosystem impacts by controlling their host community through lytic predator-prey dynamics. However, the mechanisms by which lysogenic viruses influence their host-microbial community are less clear. In hot springs, lysogeny is considered an active lifestyle, yet it has not been systematically studied in all habitats, with phototrophic microbial mats (PMMs) being particularly not studied. We carried out viral metagenomics following in situ mitomycin C induction experiments in PMMs from Porcelana hot spring (Northern Patagonia, Chile). The compositional changes of viral communities at two different sites were analyzed at the genomic and gene levels. Furthermore, the presence of integrated prophage sequences in environmental metagenome-assembled genomes from published Porcelana PMM metagenomes was analyzed. Our results suggest that virus-specific replicative cycles (lytic and lysogenic) were associated with specific host taxa with different metabolic capacities. One of the most abundant lytic viral groups corresponded to cyanophages, which would infect the cyanobacteria Fischerella, the most active and dominant primary producer in thermophilic PMMs. Likewise, lysogenic viruses were related exclusively to chemoheterotrophic bacteria from the phyla Proteobacteria, Firmicutes, and Actinobacteria. These temperate viruses possess accessory genes to sense or control stress-related processes in their hosts, such as sporulation and biofilm formation. Taken together, these observations suggest a nexus between the ecological role of the host (metabolism) and the type of viral lifestyle in thermophilic PMMs. This has direct implications in viral ecology, where the lysogenic-lytic switch is determined by nutrient abundance and microbial density but also by the metabolism type that prevails in the host community. IMPORTANCE Hot springs harbor microbial communities dominated by a limited variety of microorganisms and, as such, have become a model for studying community ecology and understanding how biotic and abiotic interactions shape their structure. Viruses in hot springs are shown to be ubiquitous, numerous, and active components of these communities. However, lytic and lysogenic viral communities of thermophilic phototrophic microbial mats (PMMs) remain largely unexplored. In this work, we use the power of viral metagenomics to reveal changes in the viral community following a mitomycin C induction experiment in PMMs. The importance of our research is that it will improve our understanding of viral lifestyles in PMMs via exploring the differences in the composition of natural and induced viral communities at the genome and gene levels. This novel information will contribute to deciphering which biotic and abiotic factors may control the transitions between lytic and lysogenic cycles in these extreme environments.
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5
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Closing Clostridium botulinum Group III Genomes Using Long-Read Sequencing. Microbiol Resour Announc 2021; 10:e0136420. [PMID: 34080898 PMCID: PMC8354527 DOI: 10.1128/mra.01364-20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Clostridium botulinum group III is the anaerobic Gram-positive bacterium producing the deadly neurotoxin responsible for animal botulism. Here, we used long-read sequencing to produce four complete genomes from Clostridium botulinum group III neurotoxin types C, D, C/D, and D/C. The protocol for obtaining high-molecular-weight DNA from C. botulinum group III is described.
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6
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Piligrimova EG, Kazantseva OA, Kazantsev AN, Nikulin NA, Skorynina AV, Koposova ON, Shadrin AM. Putative plasmid prophages of Bacillus cereus sensu lato may hold the key to undiscovered phage diversity. Sci Rep 2021; 11:7611. [PMID: 33828147 PMCID: PMC8026635 DOI: 10.1038/s41598-021-87111-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 03/22/2021] [Indexed: 11/26/2022] Open
Abstract
Bacteriophages are bacterial viruses and the most abundant biological entities on Earth. Temperate bacteriophages can form prophages stably maintained in the host population: they either integrate into the host genome or replicate as plasmids in the host cytoplasm. As shown, tailed temperate bacteriophages may form circular plasmid prophages in many bacterial species of the taxa Firmicutes, Gammaproteobacteria and Spirochaetes. The actual number of such prophages is thought to be underestimated for two main reasons: first, in bacterial whole genome-sequencing assemblies, they are difficult to distinguish from actual plasmids; second, there is an absence of experimental studies which are vital to confirm their existence. In Firmicutes, such prophages appear to be especially numerous. In the present study, we identified 23 genomes from species of the Bacillus cereus group that were deposited in GenBank as plasmids and may belong to plasmid prophages with little or no homology to known viruses. We consider these putative prophages worth experimental assays since it will broaden our knowledge of phage diversity and suggest that more attention be paid to such molecules in all bacterial sequencing projects as this will help in identifying previously unknown phages.
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Affiliation(s)
- Emma G Piligrimova
- Laboratory of Bacteriophage Biology, G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Federal Research Center, 142290, Pushchino, Russia.
| | - Olesya A Kazantseva
- Laboratory of Bacteriophage Biology, G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Federal Research Center, 142290, Pushchino, Russia
| | - Andrey N Kazantsev
- P. N. Lebedev Physical Institute of the Russian Academy of Sciences, Pushchino Radio Astronomy Observatory, Pushchino, 142290, Russia
| | - Nikita A Nikulin
- Laboratory of Bacteriophage Biology, G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Federal Research Center, 142290, Pushchino, Russia
| | - Anna V Skorynina
- Laboratory of Bacteriophage Biology, G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Federal Research Center, 142290, Pushchino, Russia
| | - Olga N Koposova
- Laboratory of Bacteriophage Biology, G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Federal Research Center, 142290, Pushchino, Russia
| | - Andrey M Shadrin
- Laboratory of Bacteriophage Biology, G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Federal Research Center, 142290, Pushchino, Russia.
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MacCready JS, Basalla JL, Vecchiarelli AG. Origin and Evolution of Carboxysome Positioning Systems in Cyanobacteria. Mol Biol Evol 2021; 37:1434-1451. [PMID: 31899489 PMCID: PMC7182216 DOI: 10.1093/molbev/msz308] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Carboxysomes are protein-based organelles that are essential for allowing cyanobacteria to fix CO2. Previously, we identified a two-component system, McdAB, responsible for equidistantly positioning carboxysomes in the model cyanobacterium Synechococcus elongatus PCC 7942 (MacCready JS, Hakim P, Young EJ, Hu L, Liu J, Osteryoung KW, Vecchiarelli AG, Ducat DC. 2018. Protein gradients on the nucleoid position the carbon-fixing organelles of cyanobacteria. eLife 7:pii:e39723). McdA, a ParA-type ATPase, nonspecifically binds the nucleoid in the presence of ATP. McdB, a novel factor that directly binds carboxysomes, displaces McdA from the nucleoid. Removal of McdA from the nucleoid in the vicinity of carboxysomes by McdB causes a global break in McdA symmetry, and carboxysome motion occurs via a Brownian-ratchet-based mechanism toward the highest concentration of McdA. Despite the importance for cyanobacteria to properly position their carboxysomes, whether the McdAB system is widespread among cyanobacteria remains an open question. Here, we show that the McdAB system is widespread among β-cyanobacteria, often clustering with carboxysome-related components, and is absent in α-cyanobacteria. Moreover, we show that two distinct McdAB systems exist in β-cyanobacteria, with Type 2 systems being the most ancestral and abundant, and Type 1 systems, like that of S. elongatus, possibly being acquired more recently. Lastly, all McdB proteins share the sequence signatures of a protein capable of undergoing liquid–liquid phase separation. Indeed, we find that representatives of both McdB types undergo liquid–liquid phase separation in vitro, the first example of a ParA-type ATPase partner protein to exhibit this behavior. Our results have broader implications for understanding carboxysome evolution, biogenesis, homeostasis, and positioning in cyanobacteria.
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Affiliation(s)
- Joshua S MacCready
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI
| | - Joseph L Basalla
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI
| | - Anthony G Vecchiarelli
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI
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M. Iyer L, Anantharaman V, Krishnan A, Burroughs AM, Aravind L. Jumbo Phages: A Comparative Genomic Overview of Core Functions and Adaptions for Biological Conflicts. Viruses 2021; 13:v13010063. [PMID: 33466489 PMCID: PMC7824862 DOI: 10.3390/v13010063] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 12/31/2020] [Accepted: 12/31/2020] [Indexed: 02/07/2023] Open
Abstract
Jumbo phages have attracted much attention by virtue of their extraordinary genome size and unusual aspects of biology. By performing a comparative genomics analysis of 224 jumbo phages, we suggest an objective inclusion criterion based on genome size distributions and present a synthetic overview of their manifold adaptations across major biological systems. By means of clustering and principal component analysis of the phyletic patterns of conserved genes, all known jumbo phages can be classified into three higher-order groups, which include both myoviral and siphoviral morphologies indicating multiple independent origins from smaller predecessors. Our study uncovers several under-appreciated or unreported aspects of the DNA replication, recombination, transcription and virion maturation systems. Leveraging sensitive sequence analysis methods, we identify novel protein-modifying enzymes that might help hijack the host-machinery. Focusing on host–virus conflicts, we detect strategies used to counter different wings of the bacterial immune system, such as cyclic nucleotide- and NAD+-dependent effector-activation, and prevention of superinfection during pseudolysogeny. We reconstruct the RNA-repair systems of jumbo phages that counter the consequences of RNA-targeting host effectors. These findings also suggest that several jumbo phage proteins provide a snapshot of the systems found in ancient replicons preceding the last universal ancestor of cellular life.
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Affiliation(s)
- Lakshminarayan M. Iyer
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA; (L.M.I.); (V.A.); (A.M.B.)
| | - Vivek Anantharaman
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA; (L.M.I.); (V.A.); (A.M.B.)
| | - Arunkumar Krishnan
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Berhampur, Odisha 760010, India;
| | - A. Maxwell Burroughs
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA; (L.M.I.); (V.A.); (A.M.B.)
| | - L. Aravind
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA; (L.M.I.); (V.A.); (A.M.B.)
- Correspondence:
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9
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Abstract
Since their discovery more than 100 years ago, the viruses that infect bacteria (bacteriophages) have been widely studied as model systems. Largely overlooked, however, have been "jumbo phages," with genome sizes ranging from 200 to 500 kbp. Jumbo phages generally have large virions with complex structures and a broad host spectrum. While the majority of jumbo phage genes are poorly functionally characterized, recent work has discovered many unique biological features, including a conserved tubulin homolog that coordinates a proteinaceous nucleus-like compartment that houses and segregates phage DNA. The tubulin spindle displays dynamic instability and centers the phage nucleus within the bacterial host during phage infection for optimal reproduction. The shell provides robust physical protection for the enclosed phage genomes against attack from DNA-targeting bacterial immune systems, thereby endowing jumbo phages with broad resistance. In this review, we focus on the current knowledge of the cytoskeletal elements and the specialized nuclear compartment derived from jumbo phages, and we highlight their importance in facilitating spatial and temporal organization over the viral life cycle. Additionally, we discuss the evolutionary relationships between jumbo phages and eukaryotic viruses, as well as the therapeutic potential and drawbacks of jumbo phages as antimicrobial agents in phage therapy.
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10
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Hayashi I. The C-terminal region of the plasmid partitioning protein TubY is a tetramer that can bind membranes and DNA. J Biol Chem 2020; 295:17770-17780. [PMID: 33454013 PMCID: PMC7762940 DOI: 10.1074/jbc.ra120.014705] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 10/13/2020] [Indexed: 01/07/2023] Open
Abstract
Bacterial low-copy-number plasmids require partition (par) systems to ensure their stable inheritance by daughter cells. In general, these systems consist of three components: a centromeric DNA sequence, a centromere-binding protein and a nucleotide hydrolase that polymerizes and functions as a motor. Type III systems, however, segregate plasmids using three proteins: the FtsZ/tubulin-like GTPase TubZ, the centromere-binding protein TubR and the MerR-like transcriptional regulator TubY. Although the TubZ filament is sufficient to transport the TubR-centromere complex in vitro, TubY is still necessary for the stable maintenance of the plasmid. TubY contains an N-terminal DNA-binding helix-turn-helix motif and a C-terminal coiled-coil followed by a cluster of lysine residues. This study determined the crystal structure of the C-terminal domain of TubY from the Bacillus cereus pXO1-like plasmid and showed that it forms a tetrameric parallel four-helix bundle that differs from the typical MerR family proteins with a dimeric anti-parallel coiled-coil. Biochemical analyses revealed that the C-terminal tail with the conserved lysine cluster helps TubY to stably associate with the TubR-centromere complex as well as to nonspecifically bind DNA. Furthermore, this C-terminal tail forms an amphipathic helix in the presence of lipids but must oligomerize to localize the protein to the membrane in vivo. Taken together, these data suggest that TubY is a component of the nucleoprotein complex within the partitioning machinery, and that lipid membranes act as mediators of type III systems.
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Affiliation(s)
- Ikuko Hayashi
- Department of Medical Life Science, Yokohama City University, Tsurumi, Yokohama, Kanagawa, Japan
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11
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Sakaguchi Y, Uchiyama J, Také A, Gotoh K, Sakaguchi M, Suzuki T, Yamamoto Y, Hosomi K, Kohda T, Mukamoto M, Kozaki S, Hayashi S, Oguma K. Analysis of a plasmid encoding botulinum neurotoxin type G gene in Clostridium argentinense. Anaerobe 2020; 66:102281. [PMID: 33059044 DOI: 10.1016/j.anaerobe.2020.102281] [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: 08/06/2020] [Revised: 09/17/2020] [Accepted: 10/01/2020] [Indexed: 11/25/2022]
Abstract
Clostridium argentinense produces botulinum neurotoxin type G (BoNT/G). We sequenced and analyzed the plasmid harboring the bont/G gene, designated pCAG, in C. argentinense strain 2740. The pCAG consisted of 140,070 bp containing the bont/G gene cluster. Although this gene cluster showed high similarities in its DNA sequence and ORF arrangement to those of other bont gene clusters, the other regions of the plasmid did not. A phylogenetic study suggested that pCAG had a unique evolutionary history compared with other clostridial bont-harboring plasmids. This suggests that pCAG is possibly a novel type of plasmid expressing the bont/G gene in C. argentinense.
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Affiliation(s)
- Yoshihiko Sakaguchi
- Department of Microbiology, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan.
| | - Jumpei Uchiyama
- Laboratory of Veterinary Microbiology I, School of Veterinary Medicine, Azabu University, Sagamihara, Kanagawa, Japan
| | - Akira Také
- Department of Microbiology, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
| | - Kazuyoshi Gotoh
- Department of Bacteriology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Okayama, Japan
| | - Masakiyo Sakaguchi
- Department of Cell Biology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Okayama, Japan
| | - Tomonori Suzuki
- Department of Molecular Microbiology, Faculty of Life Science, Tokyo University of Agriculture, Tokyo, Japan
| | - Yumiko Yamamoto
- Department of Bacteriology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Okayama, Japan
| | - Koji Hosomi
- Laboratory of Vaccine Materials, Center for Vaccine and Adjuvant Research, and Laboratory of Gut Environmental System, National Institutes of Biomedical Innovation, Health, and Nutrition, Ibaraki, Osaka, Japan
| | - Tomoko Kohda
- Department of Veterinary Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Izumisano, Osaka, Japan
| | - Masafumi Mukamoto
- Department of Veterinary Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Izumisano, Osaka, Japan
| | - Shunji Kozaki
- Department of Veterinary Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Izumisano, Osaka, Japan
| | - Shunji Hayashi
- Department of Microbiology, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
| | - Keiji Oguma
- Department of Bacteriology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Okayama, Japan
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Cavalier-Smith T, Chao EEY. Multidomain ribosomal protein trees and the planctobacterial origin of neomura (eukaryotes, archaebacteria). PROTOPLASMA 2020. [PMID: 31900730 DOI: 10.1007/s00709-019-01442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Palaeontologically, eubacteria are > 3× older than neomura (eukaryotes, archaebacteria). Cell biology contrasts ancestral eubacterial murein peptidoglycan walls and derived neomuran N-linked glycoprotein coats/walls. Misinterpreting long stems connecting clade neomura to eubacteria on ribosomal sequence trees (plus misinterpreted protein paralogue trees) obscured this historical pattern. Universal multiprotein ribosomal protein (RP) trees, more accurate than rRNA trees, are taxonomically undersampled. To reduce contradictions with genically richer eukaryote trees and improve eubacterial phylogeny, we constructed site-heterogeneous and maximum-likelihood universal three-domain, two-domain, and single-domain trees for 143 eukaryotes (branching now congruent with 187-protein trees), 60 archaebacteria, and 151 taxonomically representative eubacteria, using 51 and 26 RPs. Site-heterogeneous trees greatly improve eubacterial phylogeny and higher classification, e.g. showing gracilicute monophyly, that many 'rDNA-phyla' belong in Proteobacteria, and reveal robust new phyla Synthermota and Aquithermota. Monoderm Posibacteria and Mollicutes (two separate wall losses) are both polyphyletic: multiple outer membrane losses in Endobacteria occurred separately from Actinobacteria; neither phylum is related to Chloroflexi, the most divergent prokaryotes, which originated photosynthesis (new model proposed). RP trees support an eozoan root for eukaryotes and are consistent with archaebacteria being their sisters and rooted between Filarchaeota (=Proteoarchaeota, including 'Asgardia') and Euryarchaeota sensu-lato (including ultrasimplified 'DPANN' whose long branches often distort trees). Two-domain trees group eukaryotes within Planctobacteria, and archaebacteria with Planctobacteria/Sphingobacteria. Integrated molecular/palaeontological evidence favours negibacterial ancestors for neomura and all life. Unique presence of key pre-neomuran characters favours Planctobacteria only as ancestral to neomura, which apparently arose by coevolutionary repercussions (explained here in detail, including RP replacement) of simultaneous outer membrane and murein loss. Planctobacterial C-1 methanotrophic enzymes are likely ancestral to archaebacterial methanogenesis and β-propeller-α-solenoid proteins to eukaryotic vesicle coats, nuclear-pore-complexes, and intraciliary transport. Planctobacterial chaperone-independent 4/5-protofilament microtubules and MamK actin-ancestors prepared for eukaryote intracellular motility, mitosis, cytokinesis, and phagocytosis. We refute numerous wrong ideas about the universal tree.
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Affiliation(s)
| | - Ema E-Yung Chao
- Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK
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13
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Cavalier-Smith T, Chao EEY. Multidomain ribosomal protein trees and the planctobacterial origin of neomura (eukaryotes, archaebacteria). PROTOPLASMA 2020; 257:621-753. [PMID: 31900730 PMCID: PMC7203096 DOI: 10.1007/s00709-019-01442-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 09/19/2019] [Indexed: 05/02/2023]
Abstract
Palaeontologically, eubacteria are > 3× older than neomura (eukaryotes, archaebacteria). Cell biology contrasts ancestral eubacterial murein peptidoglycan walls and derived neomuran N-linked glycoprotein coats/walls. Misinterpreting long stems connecting clade neomura to eubacteria on ribosomal sequence trees (plus misinterpreted protein paralogue trees) obscured this historical pattern. Universal multiprotein ribosomal protein (RP) trees, more accurate than rRNA trees, are taxonomically undersampled. To reduce contradictions with genically richer eukaryote trees and improve eubacterial phylogeny, we constructed site-heterogeneous and maximum-likelihood universal three-domain, two-domain, and single-domain trees for 143 eukaryotes (branching now congruent with 187-protein trees), 60 archaebacteria, and 151 taxonomically representative eubacteria, using 51 and 26 RPs. Site-heterogeneous trees greatly improve eubacterial phylogeny and higher classification, e.g. showing gracilicute monophyly, that many 'rDNA-phyla' belong in Proteobacteria, and reveal robust new phyla Synthermota and Aquithermota. Monoderm Posibacteria and Mollicutes (two separate wall losses) are both polyphyletic: multiple outer membrane losses in Endobacteria occurred separately from Actinobacteria; neither phylum is related to Chloroflexi, the most divergent prokaryotes, which originated photosynthesis (new model proposed). RP trees support an eozoan root for eukaryotes and are consistent with archaebacteria being their sisters and rooted between Filarchaeota (=Proteoarchaeota, including 'Asgardia') and Euryarchaeota sensu-lato (including ultrasimplified 'DPANN' whose long branches often distort trees). Two-domain trees group eukaryotes within Planctobacteria, and archaebacteria with Planctobacteria/Sphingobacteria. Integrated molecular/palaeontological evidence favours negibacterial ancestors for neomura and all life. Unique presence of key pre-neomuran characters favours Planctobacteria only as ancestral to neomura, which apparently arose by coevolutionary repercussions (explained here in detail, including RP replacement) of simultaneous outer membrane and murein loss. Planctobacterial C-1 methanotrophic enzymes are likely ancestral to archaebacterial methanogenesis and β-propeller-α-solenoid proteins to eukaryotic vesicle coats, nuclear-pore-complexes, and intraciliary transport. Planctobacterial chaperone-independent 4/5-protofilament microtubules and MamK actin-ancestors prepared for eukaryote intracellular motility, mitosis, cytokinesis, and phagocytosis. We refute numerous wrong ideas about the universal tree.
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Affiliation(s)
| | - Ema E-Yung Chao
- Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK
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14
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Abstract
Plasmids are ubiquitous in the microbial world and have been identified in almost all species of bacteria that have been examined. Their localization inside the bacterial cell has been examined for about two decades; typically, they are not randomly distributed, and their positioning depends on copy number and their mode of segregation. Low-copy-number plasmids promote their own stable inheritance in their bacterial hosts by encoding active partition systems, which ensure that copies are positioned in both halves of a dividing cell. High-copy plasmids rely on passive diffusion of some copies, but many remain clustered together in the nucleoid-free regions of the cell. Here we review plasmid localization and partition (Par) systems, with particular emphasis on plasmids from Enterobacteriaceae and on recent results describing the in vivo localization properties and molecular mechanisms of each system. Partition systems also cause plasmid incompatibility such that distinct plasmids (with different replicons) with the same Par system cannot be stably maintained in the same cells. We discuss how partition-mediated incompatibility is a consequence of the partition mechanism.
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Affiliation(s)
- Jean-Yves Bouet
- Laboratoire de Microbiologie et Génétique Moléculaires, Centre de Biologie Intégrative (CBI), Centre National de la Recherche Scientifique (CNRS), Université de Toulouse, UPS, F-31000 Toulouse, France
| | - Barbara E Funnell
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada M5G 1M1
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15
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Hayashi I, Oda T, Sato M, Fuchigami S. Cooperative DNA Binding of the Plasmid Partitioning Protein TubR from the Bacillus cereus pXO1 Plasmid. J Mol Biol 2018; 430:5015-5028. [PMID: 30414406 DOI: 10.1016/j.jmb.2018.11.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 11/01/2018] [Accepted: 11/01/2018] [Indexed: 11/19/2022]
Abstract
Tubulin/FtsZ-like GTPase TubZ is responsible for maintaining the stability of pXO1-like plasmids in virulent Bacilli. TubZ forms a filament in a GTP-dependent manner, and like other partitioning systems of low-copy-number plasmids, it requires the centromere-binding protein TubR that connects the plasmid to the TubZ filament. Systems regulating TubZ partitioning have been identified in Clostridium prophages as well as virulent Bacillus species, in which TubZ facilitates partitioning by binding and towing the segrosome: the nucleoprotein complex composed of TubR and the centromere. However, the molecular mechanisms of segrosome assembly and the transient on-off interactions between the segrosome and the TubZ filament remain poorly understood. Here, we determined the crystal structure of TubR from Bacillus cereus at 2.0-Å resolution and investigated the DNA-binding ability of TubR using hydroxyl radical footprinting and electrophoretic mobility shift assays. The TubR dimer possesses 2-fold symmetry and binds to a 15-bp palindromic consensus sequence in the tubRZ promoter region. Continuous TubR-binding sites overlap each other, which enables efficient binding of TubR in a cooperative manner. Interestingly, the segrosome adopts an extended DNA-protein filament structure and likely gains conformational flexibility by introducing non-consensus residues into the palindromes in an asymmetric manner. Together, our experimental results and structural model indicate that the unique centromere recognition mechanism of TubR allows transient complex formation between the segrosome and the dynamic polymer of TubZ.
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Affiliation(s)
- Ikuko Hayashi
- Department of Medical Life Science, Yokohama City University, 1-7-29 Suehiro, Tsurumi, Yokohama, Kanagawa 230-0045, Japan.
| | - Takashi Oda
- Department of Medical Life Science, Yokohama City University, 1-7-29 Suehiro, Tsurumi, Yokohama, Kanagawa 230-0045, Japan
| | - Mamoru Sato
- Department of Medical Life Science, Yokohama City University, 1-7-29 Suehiro, Tsurumi, Yokohama, Kanagawa 230-0045, Japan
| | - Sotaro Fuchigami
- Department of Medical Life Science, Yokohama City University, 1-7-29 Suehiro, Tsurumi, Yokohama, Kanagawa 230-0045, Japan
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16
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A toxin-antitoxin system is essential for the stability of mosquitocidal plasmid pBsph of Lysinibacillus sphaericus. Microbiol Res 2018; 214:114-122. [PMID: 30031473 DOI: 10.1016/j.micres.2018.06.013] [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] [Received: 05/12/2018] [Revised: 06/13/2018] [Accepted: 06/23/2018] [Indexed: 11/22/2022]
Abstract
Lysinibacillus sphaericus C3-41 carries a large low-copy-number plasmid pBsph, which encodes binary toxin proteins. Our previous study found that the transcriptional activator TubX plays an important role in the newly identified type Ⅲ TubRZC replication/partition system in pBsph, and that a vector consisting of tubRZC and tubX is not as stable as pBsph, indicating the presence of other maintenance module(s). In this study, we identified that orf9 and orf10 are necessary for the stability of pBsph by a series of deletion and complementation experiments. Bioinformatics analysis showed that ORF9 contains a PIN domain of VapBC toxin-antitoxin (TA) system, whereas ORF10 share no significant sequence similarity to any of the characterized antitoxins in the database. Further studies revealed that orf9 and orf10 are transcribed as an operon. The overexpression of ORF9 repressed the growth of both Escherichia coli and L. sphaericus, which can be alleviated by overexpression of ORF10. The deletion of orf10 individually or orf9-10 together resulted a decrease on plasmid stability which was restored by the complementation of corresponding gene(s), suggesting that ORF10 plays an important role in plasmid stability. In addition, it was found the plasmid stability is related with the transcription level of tubRZ, and overexpression of TubRZ could neutralize the negative effect on plasmid stability caused by the deletion of orf9-orf10. Moreover, the recombinant vector containing tubRZC, tubX and orf9-10 was more stable than the ones containing only tubRZC and either tubX or orf9-10. The data indicate that the plasmid maintenance system on pBsph includes orf9-orf10 TA system.
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Martín-García B, Martín-González A, Carrasco C, Hernández-Arriaga AM, Ruíz-Quero R, Díaz-Orejas R, Aicart-Ramos C, Moreno-Herrero F, Oliva MA. The TubR-centromere complex adopts a double-ring segrosome structure in Type III partition systems. Nucleic Acids Res 2018; 46:5704-5716. [PMID: 29762781 PMCID: PMC6009700 DOI: 10.1093/nar/gky370] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 04/27/2018] [Indexed: 11/26/2022] Open
Abstract
In prokaryotes, the centromere is a specialized segment of DNA that promotes the assembly of the segrosome upon binding of the Centromere Binding Protein (CBP). The segrosome structure exposes a specific surface for the interaction of the CBP with the motor protein that mediates DNA movement during cell division. Additionally, the CBP usually controls the transcriptional regulation of the segregation system as a cell cycle checkpoint. Correct segrosome functioning is therefore indispensable for accurate DNA segregation. Here, we combine biochemical reconstruction and structural and biophysical analysis to bring light to the architecture of the segrosome complex in Type III partition systems. We present the particular features of the centromere site, tubC, of the model system encoded in Clostridium botulinum prophage c-st. We find that the split centromere site contains two different iterons involved in the binding and spreading of the CBP, TubR. The resulting nucleoprotein complex consists of a novel double-ring structure that covers part of the predicted promoter. Single molecule data provides a mechanism for the formation of the segrosome structure based on DNA bending and unwinding upon TubR binding.
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Affiliation(s)
- Bárbara Martín-García
- Department of Structural and Chemical Biology, CSIC-Centro de Investigaciones Biológicas, Madrid 28040, Spain
| | | | - Carolina Carrasco
- Department of Macromolecular Structures, CSIC-Centro Nacional de Biotecnología, Madrid 28049, Spain
| | - Ana M Hernández-Arriaga
- Department of Structural and Chemical Biology, CSIC-Centro de Investigaciones Biológicas, Madrid 28040, Spain
| | - Rubén Ruíz-Quero
- Department of Structural and Chemical Biology, CSIC-Centro de Investigaciones Biológicas, Madrid 28040, Spain
| | - Ramón Díaz-Orejas
- Department of Structural and Chemical Biology, CSIC-Centro de Investigaciones Biológicas, Madrid 28040, Spain
| | - Clara Aicart-Ramos
- Department of Macromolecular Structures, CSIC-Centro Nacional de Biotecnología, Madrid 28049, Spain
| | - Fernando Moreno-Herrero
- Department of Macromolecular Structures, CSIC-Centro Nacional de Biotecnología, Madrid 28049, Spain
| | - María A Oliva
- Department of Structural and Chemical Biology, CSIC-Centro de Investigaciones Biológicas, Madrid 28040, Spain
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18
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Abstract
Microtubules (MTs) form a rapidly adaptable network of filaments that radiate throughout the cell. These dynamic arrays facilitate a wide range of cellular processes, including the capture, transport, and spatial organization of cargos and organelles, as well as changes in cell shape, polarity, and motility. Nucleating from MT-organizing centers, including but by no means limited to the centrosome, MTs undergo rapid transitions through phases of growth, pause, and catastrophe, continuously exploring and adapting to the intracellular environment. Subsets of MTs can become stabilized in response to environmental cues, acquiring distinguishing posttranslational modifications and performing discrete functions as specialized tracks for cargo trafficking. The dynamic behavior and organization of the MT array is regulated by MT-associated proteins (MAPs), which include a subset of highly specialized plus-end-tracking proteins (+TIPs) that respond to signaling cues to alter MT behavior. As pathogenic cargos, viruses require MTs to transport to and from their intracellular sites of replication. While interactions with and functions for MT motor proteins are well characterized and extensively reviewed for many viruses, this review focuses on MT filaments themselves. Changes in the spatial organization and dynamics of the MT array, mediated by virus- or host-induced changes to MT regulatory proteins, not only play a central role in the intracellular transport of virus particles but also regulate a wider range of processes critical to the outcome of infection.
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The Contribution of Bacteriophages to the Biology and Virulence of Pathogenic Clostridia. ADVANCES IN APPLIED MICROBIOLOGY 2017; 101:169-200. [PMID: 29050666 DOI: 10.1016/bs.aambs.2017.05.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Bacteriophages are key players in the evolution of most bacteria. Temperate phages have been associated with virulence of some of the deadliest pathogenic bacteria. Among the most notorious cases, the genes encoding the botulinum neurotoxin produced by Clostridium botulinum types C and D and the α-toxin (TcnA) produced by Clostridium novyi are both encoded within prophage genomes. Clostridium difficile is another important human pathogen and the recent identification of a complete binary toxin locus (CdtLoc) carried on a C. difficile prophage raises the potential for horizontal transfer of toxin genes by mobile genetic elements. Although the TcdA and TcdB toxins produced by C. difficile have never been found outside the pathogenicity locus (PaLoc), some prophages can still influence their production. Prophages can alter the expression of several metabolic and regulatory genes in C. difficile, as well as cell surface proteins such as CwpV, which confers phage resistance. Homologs of an Agr-like quorum sensing system have been identified in a C. difficile prophage, suggesting that it could possibly participate in cell-cell communication. Yet, other C. difficile prophages contain riboswitches predicted to recognize the secondary messenger molecule c-di-GMP involved in bacterial multicellular behaviors. Altogether, recent findings on clostridial phages underline the diversity of mechanisms and intricate relationship linking phages with their host. Here, milestone discoveries linking phages and virulence of some of the most pathogenic clostridial species will be retraced, with a focus on C. botulinum, C. novyi, C. difficile, and Clostridium perfringens phages, for which evidences are mostly available.
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20
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TubZ filament assembly dynamics requires the flexible C-terminal tail. Sci Rep 2017; 7:43342. [PMID: 28230082 PMCID: PMC5322520 DOI: 10.1038/srep43342] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 01/24/2017] [Indexed: 11/12/2022] Open
Abstract
Cytomotive filaments are essential for the spatial organization in cells, showing a dynamic behavior based on nucleotide hydrolysis. TubZ is a tubulin-like protein that functions in extrachromosomal DNA movement within bacteria. TubZ filaments grow in a helical fashion following treadmilling or dynamic instability, although the underlying mechanism is unclear. We have unraveled the molecular basis for filament assembly and dynamics combining electron and atomic force microscopy and biochemical analyses. Our findings suggest that GTP caps retain the filament helical structure and hydrolysis triggers filament stiffening upon disassembly. We show that the TubZ C-terminal tail is an unstructured domain that fulfills multiple functions contributing to the filament helical arrangement, the polymer remodeling into tubulin-like rings and the full disassembly process. This C-terminal tail displays the binding site for partner proteins and we report how it modulates the interaction of the regulator protein TubY.
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21
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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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22
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Abstract
A family of tubulin-related proteins (TubZs) has been identified in prokaryotes as being important for the inheritance of virulence plasmids of several pathogenic Bacilli and also being implicated in the lysogenic life cycle of several bacteriophages. Cell biological studies and reconstitution experiments revealed that TubZs function as prokaryotic cytomotive filaments, providing one-dimensional motive forces. Plasmid-borne TubZ filaments most likely transport plasmid centromeric complexes by depolymerisation, pulling on the plasmid DNA, in vitro. In contrast, phage-borne TubZ (PhuZ) pushes bacteriophage particles (virions) to mid cell by filament growth. Structural studies by both crystallography and electron cryo-microscopy of multiple proteins, both from the plasmid partitioning sub-group and the bacteriophage virion centring group of TubZ homologues, allow a detailed consideration of the structural phylogeny of the group as a whole, while complete structures of both crystallographic protofilaments at high resolution and fully polymerised filaments at intermediate resolution by cryo-EM have revealed details of the polymerisation behaviour of both TubZ sub-groups.
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Oliva MA. Segrosome Complex Formation during DNA Trafficking in Bacterial Cell Division. Front Mol Biosci 2016; 3:51. [PMID: 27668216 PMCID: PMC5016525 DOI: 10.3389/fmolb.2016.00051] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 08/24/2016] [Indexed: 12/18/2022] Open
Abstract
Bacterial extrachromosomal DNAs often contribute to virulence in pathogenic organisms or facilitate adaptation to particular environments. The transmission of genetic information from one generation to the next requires sufficient partitioning of DNA molecules to ensure that at least one copy reaches each side of the division plane and is inherited by the daughter cells. Segregation of the bacterial chromosome occurs during or after replication and probably involves a strategy in which several protein complexes participate to modify the folding pattern and distribution first of the origin domain and then of the rest of the chromosome. Low-copy number plasmids rely on specialized partitioning systems, which in some cases use a mechanism that show striking similarity to eukaryotic DNA segregation. Overall, there have been multiple systems implicated in the dynamic transport of DNA cargo to a new cellular position during the cell cycle but most seem to share a common initial DNA partitioning step, involving the formation of a nucleoprotein complex called the segrosome. The particular features and complex topologies of individual segrosomes depend on both the nature of the DNA binding protein involved and on the recognized centromeric DNA sequence, both of which vary across systems. The combination of in vivo and in vitro approaches, with structural biology has significantly furthered our understanding of the mechanisms underlying DNA trafficking in bacteria. Here, I discuss recent advances and the molecular details of the DNA segregation machinery, focusing on the formation of the segrosome complex.
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Affiliation(s)
- María A Oliva
- Department of Chemical and Physical Biology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas Madrid, Spain
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The IntXO-PSL Recombination System Is a Key Component of the Second Maintenance System for Bacillus anthracis Plasmid pXO1. J Bacteriol 2016; 198:1939-1951. [PMID: 27137503 DOI: 10.1128/jb.01004-15] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 04/25/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED We previously identified three noncontiguous regions on Bacillus anthracis plasmid pXO1 that comprise a system for accurate plasmid partitioning and maintenance. However, deletion of these regions did not decrease retention of certain shortened pXO1 plasmids during vegetative growth. Using two genetic tools developed for DNA manipulation in B. anthracis (the Cre-loxP and Flp-FRT systems), we found two other noncontiguous pXO1 regions that together are sufficient for plasmid stability. This second pXO1 maintenance system includes the tubZ and tubR genes, characteristic of a type III partitioning system, and the IntXO recombinase gene (GBAA_RS29165), encoding a tyrosine recombinase, along with its adjacent 37-bp perfect stem-loop (PSL) target. Insertion of either the tubZ and tubR genes or the IntXO-PSL system into an unstable mini-pXO1 plasmid did not restore plasmid stability. The need for the two components of the second pXO1 maintenance system follows from the sequential roles of IntXO-PSL in generating monomeric circular daughter pXO1 molecules (thereby presumably preventing dimer catastrophe) and of TubZ/TubR in partitioning the monomers during cell division. We show that the IntXO recombinase deletes DNA regions located between two PSL sites in a manner similar to the actions of the Cre-loxP and Flp-FRT systems. IMPORTANCE Tyrosine recombinases catalyze cutting and joining reactions between short specific DNA sequences. Three types of reactions occur: integration and excision of DNA segments, inversion of DNA segments, and separation of monomeric forms from replicating circular DNA molecules. Here we show that the newly discovered site-specific IntXO-PSL recombinase system that contributes to the maintenance of the B. anthracis plasmid pXO1 can be used for genome engineering in a manner similar to that of the Cre-loxP or Flp-FRT system.
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Busiek KK, Margolin W. Bacterial actin and tubulin homologs in cell growth and division. Curr Biol 2016; 25:R243-R254. [PMID: 25784047 DOI: 10.1016/j.cub.2015.01.030] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In contrast to the elaborate cytoskeletal machines harbored by eukaryotic cells, such as mitotic spindles, cytoskeletal structures detectable by typical negative stain electron microscopy are generally absent from bacterial cells. As a result, for decades it was thought that bacteria lacked cytoskeletal machines. Revolutions in genomics and fluorescence microscopy have confirmed the existence not only of smaller-scale cytoskeletal structures in bacteria, but also of widespread functional homologs of eukaryotic cytoskeletal proteins. The presence of actin, tubulin, and intermediate filament homologs in these relatively simple cells suggests that primitive cytoskeletons first arose in bacteria. In bacteria such as Escherichia coli, homologs of tubulin and actin directly interact with each other and are crucial for coordinating cell growth and division. The function and direct interactions between these proteins will be the focus of this review.
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Affiliation(s)
- Kimberly K Busiek
- Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, 6431 Fannin St., Houston, TX 77030, USA
| | - William Margolin
- Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, 6431 Fannin St., Houston, TX 77030, USA.
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Sakaguchi Y, Suzuki T, Yamamoto Y, Nishikawa A, Oguma K. Genomics of Clostridium botulinum group III strains. Res Microbiol 2015; 166:318-25. [DOI: 10.1016/j.resmic.2014.07.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 07/30/2014] [Indexed: 10/24/2022]
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27
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Donovan C, Heyer A, Pfeifer E, Polen T, Wittmann A, Krämer R, Frunzke J, Bramkamp M. A prophage-encoded actin-like protein required for efficient viral DNA replication in bacteria. Nucleic Acids Res 2015; 43:5002-16. [PMID: 25916847 PMCID: PMC4446434 DOI: 10.1093/nar/gkv374] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 04/09/2015] [Indexed: 12/31/2022] Open
Abstract
In host cells, viral replication is localized at specific subcellular sites. Viruses that infect eukaryotic and prokaryotic cells often use host-derived cytoskeletal structures, such as the actin skeleton, for intracellular positioning. Here, we describe that a prophage, CGP3, integrated into the genome of Corynebacterium glutamicum encodes an actin-like protein, AlpC. Biochemical characterization confirms that AlpC is a bona fide actin-like protein and cell biological analysis shows that AlpC forms filamentous structures upon prophage induction. The co-transcribed adaptor protein, AlpA, binds to a consensus sequence in the upstream promoter region of the alpAC operon and also interacts with AlpC, thus connecting circular phage DNA to the actin-like filaments. Transcriptome analysis revealed that alpA and alpC are among the early induced genes upon excision of the CGP3 prophage. Furthermore, qPCR analysis of mutant strains revealed that both AlpA and AlpC are required for efficient phage replication. Altogether, these data emphasize that AlpAC are crucial for the spatio-temporal organization of efficient viral replication. This is remarkably similar to actin-assisted membrane localization of eukaryotic viruses that use the actin cytoskeleton to concentrate virus particles at the egress sites and provides a link of evolutionary conserved interactions between intracellular virus transport and actin.
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Affiliation(s)
- Catriona Donovan
- Department of Biology I, Ludwig-Maximilians-University Munich, Großhaderner Str. 2-4, 82152 Planegg-Martinsried, Germany Institute for Biochemistry, University of Cologne, Zülpicherstr. 47, 50674 Cologne, Germany
| | - Antonia Heyer
- Institut für Bio- und Geowissenschaften, IBG-1: Biotechnologie, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Eugen Pfeifer
- Institut für Bio- und Geowissenschaften, IBG-1: Biotechnologie, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Tino Polen
- Institut für Bio- und Geowissenschaften, IBG-1: Biotechnologie, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Anja Wittmann
- Institute for Biochemistry, University of Cologne, Zülpicherstr. 47, 50674 Cologne, Germany
| | - Reinhard Krämer
- Institute for Biochemistry, University of Cologne, Zülpicherstr. 47, 50674 Cologne, Germany
| | - Julia Frunzke
- Institut für Bio- und Geowissenschaften, IBG-1: Biotechnologie, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Marc Bramkamp
- Department of Biology I, Ludwig-Maximilians-University Munich, Großhaderner Str. 2-4, 82152 Planegg-Martinsried, Germany Institute for Biochemistry, University of Cologne, Zülpicherstr. 47, 50674 Cologne, Germany
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28
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Reconstitution of a prokaryotic minus end-tracking system using TubRC centromeric complexes and tubulin-like protein TubZ filaments. Proc Natl Acad Sci U S A 2015; 112:E1845-50. [PMID: 25825718 DOI: 10.1073/pnas.1423746112] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Segregation of DNA is a fundamental process during cell division. The mechanism of prokaryotic DNA segregation is largely unknown, but several low-copy-number plasmids encode cytomotive filament systems of the actin type and tubulin type important for plasmid inheritance. Of these cytomotive filaments, only actin-like systems are mechanistically well characterized. In contrast, the mechanism by which filaments of tubulin-like TubZ protein mediate DNA motility is unknown. To understand polymer-driven DNA transport, we reconstituted the filaments of TubZ protein (TubZ filaments) from Bacillus thuringiensis pBtoxis plasmid with their centromeric TubRC complexes containing adaptor protein TubR and tubC DNA. TubZ alone assembled into polar filaments, which annealed laterally and treadmilled. Using single-molecule imaging, we show that TubRC complexes were not pushed by filament polymerization; instead, they processively tracked shrinking, depolymerizing minus ends. Additionally, the TubRC complex nucleated TubZ filaments and allowed for treadmilling. Overall, our results indicate a pulling mechanism for DNA transport by the TubZRC system. The discovered minus end-tracking property of the TubRC complex expands the mechanistic diversity of the prokaryotic cytoskeleton.
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Yuan Y, Peng Q, Wu D, Kou Z, Wu Y, Liu P, Gao M. Effects of actin-like proteins encoded by two Bacillus pumilus phages on unstable lysogeny, revealed by genomic analysis. Appl Environ Microbiol 2015; 81:339-50. [PMID: 25344242 PMCID: PMC4272706 DOI: 10.1128/aem.02889-14] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 10/20/2014] [Indexed: 12/16/2022] Open
Abstract
We characterized two newly isolated myoviruses, Bp8p-C and Bp8p-T, infecting the ginger rhizome rot disease pathogen Bacillus pumilus GR8. The plaque of Bp8p-T exhibited a clear center with a turbid rim, suggesting that Bp8p-T could transform into latent phage. Lysogeny assays showed that both the two phages could form latent states, while Bp8p-T could form latent phage at a higher frequency and stability than Bp8p-C. The genomes of Bp8p-C and Bp8p-T were 151,417 and 151,419 bp, respectively; both encoded 212 putative proteins, and only differed by three nucleotides. Moreover, owing to this difference, Bp8p-C encoded a truncated, putative actin-like plasmid segregation protein Gp27-C. Functional analysis of protein Gp27 showed that Gp27-T encoded by Bp8p-T exhibited higher ATPase activity and assembly ability than Gp27-C. The results indicate that the difference in Gp27 affected the phage lysogenic ability. Structural proteome analysis of Bp8p-C virion resulted in the identification of 14 structural proteins, among which a pectin lyase-like protein, a putative poly-gamma-glutamate hydrolase, and three proteins with unknown function, were firstly identified as components of the phage virion. Both phages exhibited specific lytic ability to the host strain GR8. Bp8p-C showed better control effect on the pathogen in ginger rhizome slices than Bp8p-T, suggesting that Bp8p-C has a potential application in bio-control of ginger rhizome rot disease.
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Affiliation(s)
- Yihui Yuan
- Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, People's Republic of China
| | - Qin Peng
- Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, People's Republic of China
| | - Dandan Wu
- Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, People's Republic of China
| | - Zheng Kou
- Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, People's Republic of China
| | - Yan Wu
- Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, People's Republic of China
| | - Pengming Liu
- Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, People's Republic of China
| | - Meiying Gao
- Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, People's Republic of China
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Erb ML, Kraemer JA, Coker JKC, Chaikeeratisak V, Nonejuie P, Agard DA, Pogliano J. A bacteriophage tubulin harnesses dynamic instability to center DNA in infected cells. eLife 2014; 3. [PMID: 25429514 PMCID: PMC4244570 DOI: 10.7554/elife.03197] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Accepted: 10/22/2014] [Indexed: 11/13/2022] Open
Abstract
Dynamic instability, polarity, and spatiotemporal organization are hallmarks of the microtubule cytoskeleton that allow formation of complex structures such as the eukaryotic spindle. No similar structure has been identified in prokaryotes. The bacteriophage-encoded tubulin PhuZ is required to position DNA at mid-cell, without which infectivity is compromised. Here, we show that PhuZ filaments, like microtubules, stochastically switch from growing in a distinctly polar manner to catastrophic depolymerization (dynamic instability) both in vitro and in vivo. One end of each PhuZ filament is stably anchored near the cell pole to form a spindle-like array that orients the growing ends toward the phage nucleoid so as to position it near mid-cell. Our results demonstrate how a bacteriophage can harness the properties of a tubulin-like cytoskeleton for efficient propagation. This represents the first identification of a prokaryotic tubulin with the dynamic instability of microtubules and the ability to form a simplified bipolar spindle.
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Affiliation(s)
- Marcella L Erb
- Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - James A Kraemer
- Department of Biochemistry and Biophysics, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, United States
| | - Joanna K C Coker
- Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Vorrapon Chaikeeratisak
- Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Poochit Nonejuie
- Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - David A Agard
- Department of Biochemistry and Biophysics, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, United States
| | - Joe Pogliano
- Division of Biological Sciences, University of California, San Diego, La Jolla, United States
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31
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Sui H. Inside out: tubulin cytomotive filaments versus microtubules. Structure 2014; 22:509-10. [PMID: 24717557 DOI: 10.1016/j.str.2014.03.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
In this issue of Structure, Zehr and colleagues describe a structure of a three-stranded PhuZ tubulin cytomotive filament determined at 8.6 Å resolution. This reveals an assembly mechanism different from that of microtubules, leading to a hypothesis explaining cytomotive-filament dynamics.
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Affiliation(s)
- Haixin Sui
- Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA; Department of Biomedical Sciences, School of Public Health, University at Albany, Albany, NY 12201, USA.
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32
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A novel transcriptional activator, tubX, is required for the stability of Bacillus sphaericus mosquitocidal plasmid pBsph. J Bacteriol 2014; 196:4304-14. [PMID: 25266379 DOI: 10.1128/jb.01855-14] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Stable maintenance of the low-copy-number plasmid pBsph in Bacillus sphaericus requires a partitioning (par) system that consists of a filament-forming protein, B. sphaericus TubZ (TubZ-Bs); a centromere-binding protein, TubR-Bs; and a centromere-like DNA site, tubC, composed of three blocks (I, II, and III) of 12-bp degenerate repeats. Previous studies have shown that mini-pBsph replicons encoding the TubZ system are segregationally highly unstable, whereas the native pBsph is stably maintained. However, the mechanism underlying the stability discrepancy between pBsph and its minireplicon is poorly understood. Here orf187 (encoding TubX), a gene downstream of tubZ-Bs, was found to play a role in plasmid stabilization. Null mutation or overexpression of tubX resulted in a defect in pBsph stability and a significant decrease in the level of tubRZ-Bs expression, and the TubX-null phenotype was suppressed by ectopic expression of a wild-type copy of tubX and additional tubRZ-Bs. An electrophoresis mobility shift assay (EMSA) and a DNase I footprinting assay revealed that the TubX protein bound directly to five 8-bp degenerate repeats located in the par promoter region and that TubX competed with TubR-Bs for binding to the par promoter. Further studies demonstrated that TubX significantly stimulated the transcription of the par operon in the absence of tubR-Bs, and a higher level of gene activation was observed when tubR-Bs was present. These results suggested that TubX positively regulates tubRZ-Bs transcription by interfering with TubR-Bs-mediated repression and binding directly to the tubRZ-Bs promoter region.
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Abstract
Elastic forces within DNA drive the segregation of chromosomes in bacteria.
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Affiliation(s)
- Ramanujam Srinivasan
- Ramanujam Srinivasan is in the Centre for Biosciences and Biomedical Engineering, Indian Institute of Technology, Indore, India
| | - Mohan K Balasubramanian
- Mohan K Balasubramanian is at the Warwick Medical School, University of Warwick, Coventry, United Kingdom, and the Temasek Life Sciences Laboratory, the Department of Biological Sciences and the Mechanobiology Institute, National University of Singapore, Singapore, Singapore
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34
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Identification of three noncontiguous regions on Bacillus anthracis plasmid pXO1 that are important for its maintenance. J Bacteriol 2014; 196:2921-33. [PMID: 24914182 DOI: 10.1128/jb.01747-14] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacillus anthracis pXO1 minireplicon (MR) plasmid consisting of open reading frames (ORFs) GBAA_pXO1_0020 to GBAA_pXO1_0023 is not stably maintained in B. anthracis, whereas the full-size parent pXO1 plasmid (having 181,677 bp and 217 ORFs) is extremely stable under the same growth conditions. Two genetic tools developed for DNA manipulation in B. anthracis (Cre-loxP and Flp-FRT systems) were used to identify pXO1 regions important for plasmid stability. We localized a large segment of pXO1 that enables stable plasmid maintenance during vegetative growth. Further genetic analysis identified three genes that are necessary for pXO1 maintenance: amsP (GBAA_pXO1_0069), minP (GBAA_pXO1_0082), and sojP (GBAA_pXO1_0084). Analysis of conserved domains in the corresponding proteins indicated that only AmsP (activator of maintenance system of pXO1) is predicted to bind DNA, due to its strong helix-turn-helix domain. Two conserved domains were found in the MinP protein (Min protein from pXO1): an N-terminal domain having some similarity to the B. anthracis septum site-determining protein MinD and a C-terminal domain that resembles a baculovirus single-stranded-DNA-binding protein. The SojP protein (Soj from pXO1) contains putative Walker box motifs and belongs to the ParA family of ATPases. No sequences encoding other components of type I plasmid partition systems, namely, cis-acting centromere parS and its binding ParB protein, were identified within the pXO1 genome. A model describing the role of the MinP protein in pXO1 distribution between daughter cells is proposed.
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Ge Y, Hu X, Zhao N, Shi T, Cai Q, Yuan Z. A new tubRZ operon involved in the maintenance of the Bacillus sphaericus mosquitocidal plasmid pBsph. Microbiology (Reading) 2014; 160:1112-1124. [DOI: 10.1099/mic.0.075465-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
pBsph is a mosquitocidal plasmid first identified from Bacillus sphaericus, encoding binary toxins (Bin toxins) that are highly toxic to mosquito larvae. This plasmid plays an important role in the maintenance and evolution of the bin genes in B. sphaericus. However, little is known about its replication and partitioning. Here, we identified a 2.4 kb minimal replicon of pBsph plasmid that contained an operon encoding TubR-Bs and TubZ-Bs, each of which was shown to be required for plasmid replication. TubR-Bs was shown to be a transcriptional repressor of tubRZ-Bs genes and could bind cooperatively to the replication origin of eleven 12 bp degenerate repeats in three blocks, and this binding was essential for plasmid replication. TubZ-Bs exhibited GTPase activities and interacted with TubR-Bs : DNA complex to form a ternary nucleoprotein apparatus. Electron and fluorescence microscopy revealed that TubZ-Bs assembled filaments both in vitro and in vivo, and two point mutations in TubZ-Bs (T114A and Y260A) that severely impaired the GTPase and polymerization activities were found to be defective for plasmid maintenance. Further investigation demonstrated that overproduction of TubZ-Bs-GFP or its mutant forms significantly reduced the stability of pBsph. Taken together, these results suggested that TubR-Bs and TubZ-Bs are involved in the replication and probably in the partitioning of pBsph plasmid, increasing our understanding of the genetic particularity of TubZ systems.
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Affiliation(s)
- Yong Ge
- University of the Chinese Academy of Sciences, Beijing 100039, PR China
- Key Laboratory of Applied and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China
| | - Xiaomin Hu
- Key Laboratory of Applied and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China
| | - Ni Zhao
- Key Laboratory of Applied and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China
| | - Tingyu Shi
- Key Laboratory of Applied and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China
| | - Quanxin Cai
- Key Laboratory of Applied and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China
| | - Zhiming Yuan
- Key Laboratory of Applied and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China
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36
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Zehr EA, Kraemer JA, Erb ML, Coker JKC, Montabana EA, Pogliano J, Agard DA. The structure and assembly mechanism of a novel three-stranded tubulin filament that centers phage DNA. Structure 2014; 22:539-48. [PMID: 24631461 DOI: 10.1016/j.str.2014.02.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 01/31/2014] [Accepted: 02/11/2014] [Indexed: 10/25/2022]
Abstract
Tubulins are a universally conserved protein superfamily that carry out diverse biological roles by assembling filaments with very different architectures. The underlying basis of this structural diversity is poorly understood. Here, we determine a 7.1 Å cryo-electron microscopy reconstruction of the bacteriophage-encoded PhuZ filament and provide molecular-level insight into its cooperative assembly mechanism. The PhuZ family of tubulins is required to actively center the phage within infected host cells, facilitating efficient phage replication. Our reconstruction and derived model reveal the first example of a three-stranded tubulin filament. We show that the elongated C-terminal tail simultaneously stabilizes both longitudinal and lateral interactions, which in turn define filament architecture. Identified interaction surfaces are conserved within the PhuZ family, and their mutagenesis compromises polymerization in vitro and in vivo. Combining kinetic modeling of PhuZ filament assembly and structural data, we suggest a common filament structure and assembly mechanism for the PhuZ family of tubulins.
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Affiliation(s)
- Elena A Zehr
- Department of Biochemistry and Biophysics and the Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - James A Kraemer
- Department of Biochemistry and Biophysics and the Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Marcella L Erb
- Division of Biological Sciences, University of California, San Diego, San Diego, CA 92093, USA
| | - Joanna K C Coker
- Division of Biological Sciences, University of California, San Diego, San Diego, CA 92093, USA
| | - Elizabeth A Montabana
- Department of Biochemistry and Biophysics and the Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Joe Pogliano
- Division of Biological Sciences, University of California, San Diego, San Diego, CA 92093, USA
| | - David A Agard
- Department of Biochemistry and Biophysics and the Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA.
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37
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Bacterial tubulin TubZ-Bt transitions between a two-stranded intermediate and a four-stranded filament upon GTP hydrolysis. Proc Natl Acad Sci U S A 2014; 111:3407-12. [PMID: 24550513 DOI: 10.1073/pnas.1318339111] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cytoskeletal filaments form diverse superstructures that are highly adapted for specific functions. The recently discovered TubZ subfamily of tubulins is involved in type III plasmid partitioning systems, facilitating faithful segregation of low copy-number plasmids during bacterial cell division. One such protein, TubZ-Bt, is found on the large pBtoxis plasmid in Bacillus thuringiensis, and interacts via its extended C terminus with a DNA adaptor protein TubR. Here, we use cryo-electron microscopy to determine the structure of TubZ-Bt filaments and light scattering to explore their mechanism of polymerization. Surprisingly, we find that the helical filament architecture is remarkably sensitive to nucleotide state, changing from two-stranded to four-stranded depending on the ability of TubZ-Bt to hydrolyze GTP. We present pseudoatomic models of both the two- and four-protofilament forms based on cryo-electron microscopy reconstructions (10.8 Å and 6.9 Å, respectively) of filaments formed under different nucleotide states. These data lead to a model in which the two-stranded filament is a necessary intermediate along the pathway to formation of the four-stranded filament. Such nucleotide-directed structural polymorphism is to our knowledge an unprecedented mechanism for the formation of polar filaments.
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38
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Erb ML, Pogliano J. Cytoskeletal proteins participate in conserved viral strategies across kingdoms of life. Curr Opin Microbiol 2013; 16:786-9. [PMID: 24055040 DOI: 10.1016/j.mib.2013.08.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 08/18/2013] [Indexed: 12/18/2022]
Abstract
The discovery of tubulin-like cytoskeletal proteins carried on the genomes of bacteriophages that are actively used for phage propagation during both the lytic and lysogenic cycle have revealed that there at least two ways that viruses can utilize a cytoskeleton; co-opt the host cytoskeleton or bring their own homologues. Either strategy underscores the deep evolutionary relationship between viruses and cytoskeletal proteins and points to a conservation of viral strategies that crosses the kingdoms of life. Here we review some of the most recent discoveries about tubulin cytoskeletal elements encoded by phages and compare them to some of the strategies utilized by the gammaherpesvirues of mammalian cells.
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Affiliation(s)
- Marcella L Erb
- University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, United States
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39
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Aylett CHS, Izoré T, Amos LA, Löwe J. Structure of the tubulin/FtsZ-like protein TubZ from Pseudomonas bacteriophage ΦKZ. J Mol Biol 2013; 425:2164-73. [PMID: 23528827 PMCID: PMC3678025 DOI: 10.1016/j.jmb.2013.03.019] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 03/07/2013] [Accepted: 03/08/2013] [Indexed: 11/25/2022]
Abstract
Pseudomonas ΦKZ-like bacteriophages encode a group of related tubulin/FtsZ-like proteins believed to be essential for the correct centring of replicated bacteriophage virions within the bacterial host. In this study, we present crystal structures of the tubulin/FtsZ-like protein TubZ from Pseudomonas bacteriophage ΦKZ in both the monomeric and protofilament states, revealing that ΦKZ TubZ undergoes structural changes required to polymerise, forming a canonical tubulin/FtsZ-like protofilament. Combining our structures with previous work, we propose a polymerisation–depolymerisation cycle for the Pseudomonas bacteriophage subgroup of tubulin/FtsZ-like proteins. Electron cryo-microscopy of ΦKZ TubZ filaments polymerised in vitro implies a long-pitch helical arrangement for the constituent protofilaments. Intriguingly, this feature is shared by the other known subgroup of bacteriophage tubulin/FtsZ-like proteins from Clostridium species, which are thought to be involved in partitioning the genomes of bacteriophages adopting a pseudo-lysogenic life cycle.
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40
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Abstract
Cytoskeletal elements are well known to be widespread in eukaryotes and prokaryotes, providing important, diverse functions for cells large and small. Two new studies report that some bacteriophages encode their own tubulin homologs to facilitate phage reproduction within the host cell.
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41
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Andreu JM, Oliva MA. Purification and assembly of bacterial tubulin BtubA/B and constructs bearing eukaryotic tubulin sequences. Methods Cell Biol 2013; 115:269-81. [PMID: 23973078 DOI: 10.1016/b978-0-12-407757-7.00017-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Bacterial tubulin BtubA/B is a close structural homolog of eukaryotic αβ-tubulin, thought to have originated by transfer of ancestral tubulin genes from a primitive eukaryotic cell to a bacterium, followed by divergent evolution. BtubA and BtubB are easily expressed homogeneous polypeptides that fold spontaneously without eukaryotic chaperone requirements, associate into weak BtubA/B heterodimers and assemble forming tubulin-like protofilaments. These protofilaments coalesce into pairs and bundles, or form five-protofilament tubules proposed to share the architecture of microtubules. Bacterial tubulin is an attractive framework for tubulin engineering. Potential applications include humanizing different sections of bacterial tubulin with the aims of creating recombinant binding sites for antitumor drugs, obtaining well-defined substrates for the enzymes responsible for tubulin posttranslational modification, or bacterial microtubule-like polymeric trails for motor proteins. Several divergent sequences from the surface loops of bacterial tubulin have already been replaced by the corresponding eukaryotic sequences, yielding soluble folded chimeras. We describe the purification protocol of untagged bacterial tubulin BtubA/B by means of ion exchange, size exclusion chromatography, and an assembly-disassembly cycle. This is followed by methods and examples to characterize its assembly, employing light scattering, sedimentation, and electron microscopy.
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Affiliation(s)
- José M Andreu
- Centro de Investigaciones Biológicas, CSIC, Madrid, Spain
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42
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Hoshino S, Maki T, Hayashi I. Crystallization and preliminary X-ray data analysis of the pXO1 plasmid-partitioning factor TubZ from Bacillus cereus. Acta Crystallogr Sect F Struct Biol Cryst Commun 2012; 68:1550-3. [PMID: 23192045 PMCID: PMC3509986 DOI: 10.1107/s1744309112045551] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Accepted: 11/04/2012] [Indexed: 11/10/2022]
Abstract
TubZ is a structural homologue of tubulin and FtsZ GTPases, which are involved in the type III plasmid-partitioning system. TubZ assembles into polymers in a GTP-dependent manner and drives plasmid segregation as `cytomotive' filaments. In this study, C-terminally truncated TubZ from Bacillus cereus was crystallized in the presence or absence of GDP by the hanging-drop vapour-diffusion method. The crystal of TubZ in complex with GDP belonged to the monoclinic space group P2(1), with unit-cell parameters a=67.05, b=84.49, c=67.66 Å, β=92.92°, and was non-isomorphous with GDP-bound TubZ previously crystallized in the presence of the slowly hydrolysable GTP analogue GTPγS. TubZ was also crystallized in the free form and the crystal belonged to space group P2(1), with unit-cell parameters a=53.91, b=65.54, c=58.18 Å, β=106.19°. Data were collected to 1.7 and 2.1 Å resolution for the free and GDP-bound forms, respectively.
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Affiliation(s)
- Shota Hoshino
- Department of Supramolecular Biology, Graduate School of Nanobioscience, Yokohama City University, 1-7-29 Suehiro, Tsurumi, Yokohama 230-0045, Japan
| | - Takahisa Maki
- Department of Supramolecular Biology, Graduate School of Nanobioscience, Yokohama City University, 1-7-29 Suehiro, Tsurumi, Yokohama 230-0045, Japan
| | - Ikuko Hayashi
- Department of Supramolecular Biology, Graduate School of Nanobioscience, Yokohama City University, 1-7-29 Suehiro, Tsurumi, Yokohama 230-0045, Japan
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43
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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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44
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Superstructure of the centromeric complex of TubZRC plasmid partitioning systems. Proc Natl Acad Sci U S A 2012; 109:16522-7. [PMID: 23010931 DOI: 10.1073/pnas.1210899109] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Bacterial plasmid partitioning systems segregate plasmids into each daughter cell. In the well-understood ParMRC plasmid partitioning system, adapter protein ParR binds to centromere parC, forming a helix around which the DNA is externally wrapped. This complex stabilizes the growth of a filament of actin-like ParM protein, which pushes the plasmids to the poles. The TubZRC plasmid partitioning system consists of two proteins, tubulin-like TubZ and TubR, and a DNA centromere, tubC, which perform analogous roles to those in ParMRC, despite being unrelated in sequence and structure. We have dissected in detail the binding sites that comprise Bacillus thuringiensis tubC, visualized the TubRC complex by electron microscopy, and determined a crystal structure of TubR bound to the tubC repeat. We show that the TubRC complex takes the form of a flexible DNA-protein filament, formed by lateral coating along the plasmid from tubC, the full length of which is required for the successful in vitro stabilization of TubZ filaments. We also show that TubR from Bacillus megaterium forms a helical superstructure resembling that of ParR. We suggest that the TubRC DNA-protein filament may bind to, and stabilize, the TubZ filament by forming such a ring-like structure around it. The helical superstructure of this TubRC may indicate convergent evolution between the actin-containing ParMRC and tubulin-containing TubZRC systems.
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45
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Zhang D, Aravind L. Novel transglutaminase-like peptidase and C2 domains elucidate the structure, biogenesis and evolution of the ciliary compartment. Cell Cycle 2012; 11:3861-75. [PMID: 22983010 PMCID: PMC3495828 DOI: 10.4161/cc.22068] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
In addition to their role in motility, eukaryotic cilia serve as a distinct compartment for signal transduction and regulatory sequestration of biomolecules. Recent genetic and biochemical studies have revealed an extraordinary diversity of protein complexes involved in the biogenesis of cilia during each cell cycle. Mutations in components of these complexes are at the heart of human ciliopathies such as Nephronophthisis (NPHP), Meckel-Gruber syndrome (MKS), Bardet-Biedl syndrome (BBS) and Joubert syndrome (JBTS). Despite intense studies, proteins in some of these complexes, such as the NPHP1-4-8 and the MKS, remain poorly understood. Using a combination of computational analyses we studied these complexes to identify novel domains in them which might throw new light on their functions and evolutionary origins. First, we identified both catalytically active and inactive versions of transglutaminase-like (TGL) peptidase domains in key ciliary/centrosomal proteins CC2D2A/MKS6, CC2D2B, CEP76 and CCDC135. These ciliary TGL domains appear to have originated from prokaryotic TGL domains that act as peptidases, either in a prokaryotic protein degradation system with the MoxR AAA+ ATPase, the precursor of eukaryotic dyneins and midasins, or in a peptide-ligase system with an ATP-grasp enzyme comparable to tubulin-modifying TTL proteins. We suggest that active ciliary TGL proteins are part of a cilia-specific peptidase system that might remove tubulin modifications or cleave cilia- localized proteins, while the inactive versions are likely to bind peptides and mediate key interactions during ciliogenesis. Second, we observe a vast radiation of C2 domains, which are key membrane-localization modules, in multiple ciliary proteins, including those from the NPHP1-4-8 and the MKS complexes, such as CC2D2A/MKS6, RPGRIP1, RPGRIP1L, NPHP1, NPHP4, C2CD3, AHI1/Jouberin and CEP76, most of which can be traced back to the last common eukaryotic ancestor. Identification of these TGL and C2 domains aid in the proper reconstruction of the Y-shaped linkers, which are key structures in the transitional zone of cilia, by allowing precise prediction of the multiple membrane-contacting and protein-protein interaction sites in these structures. These findings help decipher key events in the evolutionary separation of the ciliary and nuclear compartments in course of the emergence of the eukaryotic cell.
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Affiliation(s)
- Dapeng Zhang
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
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Phages find a backbone. Nat Rev Microbiol 2012; 10:522-3. [DOI: 10.1038/nrmicro2838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Hoshino S, Hayashi I. Filament formation of the FtsZ/tubulin-like protein TubZ from the Bacillus cereus pXO1 plasmid. J Biol Chem 2012; 287:32103-12. [PMID: 22847006 DOI: 10.1074/jbc.m112.373803] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Stable maintenance of low-copy-number plasmids requires partition (par) systems that consist of a nucleotide hydrolase, a DNA-binding protein, and a cis-acting DNA-binding site. The FtsZ/tubulin-like GTPase TubZ was identified as a partitioning factor of the virulence plasmids pBtoxis and pXO1 in Bacillus thuringiensis and Bacillus anthracis, respectively. TubZ exhibits high GTPase activity and assembles into polymers both in vivo and in vitro, and its "treadmilling" movement is required for plasmid stability in the cell. To investigate the molecular mechanism of pXO1 plasmid segregation by TubZ filaments, we determined the crystal structures of Bacillus cereus TubZ in apo-, GDP-, and guanosine 5'-3-O-(thio)triphosphate (GTPγS)-bound forms at resolutions of 2.1, 1.9, and 3.3 Å, respectively. Interestingly, the slowly hydrolyzable GTP analog GTPγS was hydrolyzed to GDP in the crystal. In the post-GTP hydrolysis state, GDP-bound B. cereus TubZ forms a dimer by the head-to-tail association of individual subunits in the asymmetric unit, which is similar to the protofilament formation of FtsZ and B. thuringiensis TubZ. However, the M loop interacts with the nucleotide-binding site of the adjacent subunit and stabilizes the filament structure in a different manner, which indicates that the molecular assembly of the TubZ-related par systems is not stringently conserved. Furthermore, we show that the C-terminal tail of TubZ is required for association with the DNA-binding protein TubR. Using a combination of crystallography, site-directed mutagenesis, and biochemical analysis, our results provide the structural basis of the TubZ polymer that may drive DNA segregation.
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Affiliation(s)
- Shota Hoshino
- Department of Supramolecular Biology, Graduate School of Nanobioscience, Yokohama City University, 1-7-29 Suehiro, Tsurumi, Yokohama 230-0045, Japan
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