scholarly journals Cytoplasmic Filament-Deficient Mutant ofTreponema denticola Has Pleiotropic Defects

2001 ◽  
Vol 183 (3) ◽  
pp. 1078-1084 ◽  
Author(s):  
Jacques Izard ◽  
William A. Samsonoff ◽  
Ronald J. Limberger
Keyword(s):  
Cell Division ◽  
Fluorescent Dyes ◽  
Homogeneous Distribution ◽  
Deficient Mutant ◽  
Chromosomal Dna ◽  
Erythromycin Resistance ◽  
Cytoplasmic Filaments ◽  
Insertional Inactivation ◽  
Division Process ◽  
Cytoplasmic Filament

ABSTRACT In Treponema denticola, a ribbon-like structure of cytoplasmic filaments spans the cytoplasm at all stages of the cell division process. Insertional inactivation was used as a first step to determine the function of the cytoplasmic filaments. A suicide plasmid was constructed that contained part of cfpA and a nonpolar erythromycin resistance cassette (ermF andermAM) inserted near the beginning of the gene. The plasmid was electroporated into T. denticola, and double-crossover recombinants which had the chromosomal copy of cfpAinsertionally inactivated were selected. Immunoblotting and electron microscopy confirmed the lack of cytoplasmic filaments. The mutant was further analyzed by dark-field microscopy to determine cell morphology and by the binding of two fluorescent dyes to DNA to assess the distribution of cellular nucleic acids. The cytoplasmic filament protein-deficient mutant exhibited pleiotropic defects, including highly condensed chromosomal DNA, compared to the homogeneous distribution of the DNA throughout the cytoplasm in a wild-type cell. Moreover, chains of cells are formed by the cytoplasmic filament-deficient mutant, and those cells show reduced spreading in agarose, which may be due to the abnormal cell length. The chains of cells and the highly condensed chromosomal DNA suggest that the cytoplasmic filaments may be involved in chromosome structure, segregation, or the cell division process in Treponema.

scholarly journals In Silico and Cellular Differences Related to the Cell Division Process between the A and B Races of the Colonial Microalga Botryococcus braunii

Biomolecules ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1463
Author(s):  
Xochitl Morales-de la Cruz ◽  
Alejandra Mandujano-Chávez ◽  
Daniel R. Browne ◽  
Timothy P. Devarenne ◽  
Lino Sánchez-Segura ◽  
...  
Keyword(s):  
Cell Division ◽  
Combustion Engine ◽  
Botryococcus Braunii ◽  
Slow Growth Rate ◽  
Cyclin Dependent Kinases ◽  
Multinucleated Cells ◽  
Cell Doubling Time ◽  
Division Process ◽  
Polyphosphate Bodies ◽  
Growing Conditions

Botryococcus braunii produce liquid hydrocarbons able to be processed into combustion engine fuels. Depending on the growing conditions, the cell doubling time can be up to 6 days or more, which is a slow growth rate in comparison with other microalgae. Few studies have analyzed the cell cycle of B. braunii. We did a bioinformatic comparison between the protein sequences for retinoblastoma and cyclin-dependent kinases from the A (Yamanaka) and B (Showa) races, with those sequences from other algae and Arabidopsis thaliana. Differences in the number of cyclin-dependent kinases and potential retinoblastoma phosphorylation sites between the A and B races were found. Some cyclin-dependent kinases from both races seemed to be phylogenetically more similar to A. thaliana than to other microalgae. Microscopic observations were done using several staining procedures. Race A colonies, but not race B, showed some multinucleated cells without chlorophyll. An active mitochondrial net was detected in those multinucleated cells, as well as being defined in polyphosphate bodies. These observations suggest differences in the cell division processes between the A and B races of B. braunii.

scholarly journals Complementation of a Nonmotile flaB Mutant ofBorrelia burgdorferi by Chromosomal Integration of a Plasmid Containing a Wild-Type flaB Allele

2001 ◽  
Vol 183 (22) ◽  
pp. 6558-6564 ◽  
Author(s):  
Marina L. Sartakova ◽  
Elena Y. Dobrikova ◽  
M. Abdul Motaleb ◽  
Henry P. Godfrey ◽  
Nyles W. Charon ◽  
...  
Keyword(s):  
Dna Hybridization ◽  
Kanamycin Resistance ◽  
Functional Restoration ◽  
Pcr Analysis ◽  
Null Mutant ◽  
Wild Type ◽  
Erythromycin Resistance ◽  
Cloning Vectors ◽  
Insertional Inactivation ◽  
Wave Morphology

ABSTRACT With the recent identification of antibiotic resistance phenotypes, the use of reporter genes, the isolation of null mutants by insertional inactivation, and the development of extrachromosomal cloning vectors, genetic analysis of Borrelia burgdorferi is becoming a reality. A previously described nonmotile, rod-shaped, kanamycin-resistant B. burgdorferi flaB::Km null mutant was complemented by electroporation with the erythromycin resistance plasmid pED3 (a pGK12 derivative) containing the wild-typeflaB sequence and 366 bp upstream from its initiation codon. The resulting MS17 clone possessed erythromycin and kanamycin resistance, flat-wave morphology, and microscopic and macroscopic motility. Several other electroporations with plasmids containing wild-type flaB and various lengths (198, 366, or 762 bp) of sequence upstream from the flaB gene starting codon did not lead to functional restoration of the nonmotileflaB null mutant. DNA hybridization, PCR analysis, and sequencing indicated that the wild-type flaB gene in nonmotile clones was present in the introduced extrachromosomal plasmids, while the motile MS17 clone was a merodiploid containing single tandem chromosomal copies of mutatedflaB::Km and wild-type flaBwith a 366-bp sequence upstream from its starting codon. Complementation was thus achieved only when wild-typeflaB was inserted into the borrelial chromosome. Several possible mechanisms for the failure of complementation for extrachromosomally located flaB are discussed.

Consistency of constructions for cell division processes

2015 ◽  
Vol 47 (3) ◽  
pp. 640-651 ◽  
Author(s):  
Werner Nagel ◽  
Eike Biehler
Keyword(s):  
Cell Division ◽  
Euclidean Space ◽  
Wide Class ◽  
Boundary Effects ◽  
Bounded Set ◽  
Spatial Consistency ◽  
Division Process

For a class of cell division processes in the Euclidean space ℝd, spatial consistency is investigated. This addresses the problem whether the distribution of the generated structures, restricted to a bounded set V, depends on the choice of a larger region W ⊃ V where the construction of the cell division process is performed. This can also be understood as the problem of boundary effects in the cell division procedure. It is known that the STIT tessellations are spatially consistent. In the present paper it is shown that, within a reasonable wide class of cell division processes, the STIT tessellations are the only ones that are consistent.

scholarly journals Partitioning of Chromosomal DNA during Establishment of Cellular Asymmetry in Bacillus subtilis

2002 ◽  
Vol 184 (6) ◽  
pp. 1743-1749 ◽  
Author(s):  
Joe Pogliano ◽  
Marc D. Sharp ◽  
Kit Pogliano
Keyword(s):  
Bacillus Subtilis ◽  
Cell Division ◽  
Asymmetric Cell Division ◽  
Chromosome Structure ◽  
Chromosomal Dna ◽  
Chromosome Partitioning ◽  
Cellular Asymmetry ◽  
The Future ◽  
Asymmetric Partitioning ◽  
Polar Division

ABSTRACT The switch from symmetric to asymmetric cell division is a key feature of development in many organisms, including Bacillus subtilis sporulation. Here we demonstrate that, prior to the onset of asymmetric cell division, the B. subtilis chromosome is partitioned into two unequally sized domains, with the origin-proximal one-third of the future forespore chromosome condensed near one pole of the cell. Asymmetric chromosome partitioning is independent of polar division, as it occurs in cells depleted of FtsZ but depends on two transcription factors that govern the initiation of sporulation, σH and Spo0A-P. It is also independent of chromosome partitioning proteins Spo0J and Soj, suggesting the existence of a novel mechanism controlling chromosome structure. Thus, our results demonstrate that, during sporulation, two separable events prepare B. subtilis for asymmetric cell division: the relocation of cell division sites to the cell poles and the asymmetric partitioning of the future forespore chromosome.

Enterococcus faecalis divIVA: an essential gene involved in cell division, cell growth and chromosome segregation

Microbiology ◽  
2005 ◽  
Vol 151 (5) ◽  
pp. 1381-1393 ◽  
Author(s):  
Sandra Ramirez-Arcos ◽  
Mingmin Liao ◽  
Susan Marthaler ◽  
Marc Rigden ◽  
Jo-Anne R. Dillon
Keyword(s):  
Cell Division ◽  
Enterococcus Faecalis ◽  
Chromosome Segregation ◽  
Essential Gene ◽  
Phylogenetic Distance ◽  
Multifunctional Protein ◽  
E Coli ◽  
Insertional Inactivation ◽  
Species Specific ◽  
Division Cell

Enterococcus faecalis divIVA (divIVA Ef) is an essential gene implicated in cell division and chromosome segregation. This gene was disrupted by insertional inactivation creating E. faecalis JHSR1, which was viable only when a wild-type copy of divIVA Ef was expressed in trans, confirming the essentiality of the gene. The absence of DivIVAEf in E. faecalis JHSR1 inhibited proper cell division, which resulted in abnormal cell clusters possessing enlarged cells of altered shape instead of the characteristic diplococcal morphology of enterococci. The lower viability of the divIVA Ef mutant is caused by improper nucleoid segregation and impaired septation within the numerous cells generated in each cluster. Overexpression of DivIVAEf in Escherichia coli KJB24 resulted in enlarged cells with disrupted cell division, suggesting that this round E. coli mutant strain could be used as an indicator for functionality of DivIVAEf. A Bacillus subtilis divIVA mutant was not complemented by DivIVAEf, indicating that this protein does not recognize DivIVA-specific target sites in B. subtilis, or that it does not interact with other proteins of the cell division machinery of this micro-organism. DivIVAEf also failed to complement a Streptococcus pneumoniae divIVA mutant, supporting the phylogenetic distance between Enterococcus and Streptococcus. Our results indicate that DivIVA is a species-specific multifunctional protein implicated in cell division and chromosome segregation in E. faecalis.

scholarly journals Insertion-Duplication Mutagenesis ofNeisseria: Use in Characterization of DNA Transfer Genes in the Gonococcal Genetic Island

2001 ◽  
Vol 183 (16) ◽  
pp. 4718-4726 ◽  
Author(s):  
Holly L. Hamilton ◽  
Kevin J. Schwartz ◽  
Joseph P. Dillard
Keyword(s):  
Type Iv Secretion ◽  
Phenotypic Characterization ◽  
Insertion Mutation ◽  
Dna Uptake ◽  
Chromosomal Dna ◽  
Chromosome Walking ◽  
Erythromycin Resistance ◽  
Type Iv ◽  
Transfer Genes

ABSTRACT We created plasmids for use in insertion-duplication mutagenesis (IDM) of Neisseria gonorrhoeae. This mutagenesis method has the advantage that it requires only a single cloning step prior to transformation into gonococci. Chromosomal DNA cloned into the plasmid directs insertion into the chromosome at the site of homology by a single-crossover (Campbell-type) recombination event. Two of the vectors contain an erythromycin resistance gene, ermC, with a strong promoter and in an orientation such that transcription will proceed into the cloned insert. Thus, these plasmids can be used to create insertions that are effectively nonpolar on the transcription of downstream genes. In addition to the improved ermC, the vector contains two copies of the neisserial DNA uptake sequence to facilitate high-frequency DNA uptake during transformation. Using various chromosomal DNA insert sizes, we have determined that even small inserts can target insertion mutation by this method and that the insertions are stably maintained in the gonococcal chromosome. We have used IDM to create knockouts in two genes in the gonococcal genetic island (GGI) and to clone additional regions of the GGI by a chromosome-walking procedure. Phenotypic characterization oftraG and traH mutants suggests a role for the encoded proteins in DNA secretion by a novel type IV secretion system.

scholarly journals Pachytene arrest and other meiotic effects of the start mutations in Saccharomyces cerevisiae.

Genetics ◽  
1989 ◽  
Vol 123 (1) ◽  
pp. 29-43 ◽  
Author(s):  
E O Shuster ◽  
B Byers
Keyword(s):  
Cell Division ◽  
Nuclear Division ◽  
Spindle Pole Body ◽  
Mitotic Cell ◽  
Spindle Pole ◽  
Mitotic Cell Cycle ◽  
Chromosomal Dna ◽  
Pole Body ◽  
Vegetative Cycle

Abstract Mutations in the Start class of cell division cycle genes (CDC28, CDC36 and CDC39) define the point in the G1 phase of the vegetative cycle at which the cell becomes committed to completing another round of cell division. Genetic, cytological and biochemical data demonstrate that these mutations cause meiotic cells to become arrested at pachytene following completion of both chromosomal DNA replication and spindle pole body (SPB) duplication. In contrast these mutations have previously been found to cause arrest of the mitotic cell cycle prior to either of these landmark events, so the role of the Start genes in these events during vegetative growth must be indirect. Our observations are consistent with the hypothesis that CDC28, CDC36 and CDC39 are required for irreversible commitment to nuclear division in both the mitotic and meiotic pathways. CDC28 was additionally found to be required for the SPB separation that precedes spindle formation in preparation for the second meiotic division. Cytological and genetic analyses of this requirement revealed both that such separation may fail independently at either SPB and that ascospore formation can proceed independently of SPB separation.

scholarly journals The Nucleoid Occlusion Protein SlmA Binds to Lipid Membranes

mBio ◽  
2020 ◽  
Vol 11 (5) ◽  
Author(s):  
Miguel Ángel Robles-Ramos ◽  
William Margolin ◽  
Marta Sobrinos-Sanguino ◽  
Carlos Alfonso ◽  
Germán Rivas ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cell Division ◽  
Dna Binding ◽  
Division Ring ◽  
Binding Sites ◽  
Lipid Membranes ◽  
Fine Tuning ◽  
Chromosomal Dna ◽  
Content Type ◽  
Binding Partners

ABSTRACT Protection of the chromosome from scission by the division machinery during cytokinesis is critical for bacterial survival and fitness. This is achieved by nucleoid occlusion, which, in conjunction with other mechanisms, ensures formation of the division ring at midcell. In Escherichia coli, this mechanism is mediated by SlmA, a specific DNA binding protein that antagonizes assembly of the central division protein FtsZ into a productive ring in the vicinity of the chromosome. Here, we provide evidence supporting direct interaction of SlmA with lipid membranes, tuned by its binding partners FtsZ and SlmA binding sites (SBS) on chromosomal DNA. Reconstructions in minimal membrane systems that mimic cellular environments show that SlmA binds to lipid-coated microbeads or locates at the edge of microfluidic-generated microdroplets, inside which the protein is encapsulated. DNA fragments containing SBS sequences do not seem to be recruited to the membrane by SlmA but instead compete with SlmA’s ability to bind lipids. The interaction of SlmA with FtsZ modulates this behavior, ultimately triggering membrane localization of the SBS sequences alongside the two proteins. The ability of SlmA to bind lipids uncovered in this work extends the interaction network of this multivalent regulator beyond its well-known protein and nucleic acid recognition, which may have implications in the overall spatiotemporal control of division ring assembly. IMPORTANCE Successful bacterial proliferation relies on the spatial and temporal precision of cytokinesis and its regulation by systems that protect the integrity of the nucleoid. In Escherichia coli, one of these protectors is SlmA protein, which binds to specific DNA sites around the nucleoid and helps to shield the nucleoid from inappropriate bisection by the cell division septum. Here, we discovered that SlmA not only interacts with the nucleoid and septum-associated cell division proteins but also binds directly to cytomimetic lipid membranes, adding a novel putative mechanism for regulating the local activity of these cell division proteins. We find that interaction between SlmA and lipid membranes is regulated by SlmA’s DNA binding sites and protein binding partners as well as chemical conditions, suggesting that the SlmA-membrane interactions are important for fine-tuning the regulation of nucleoid integrity during cytokinesis.

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