scholarly journals Chromosome loss from par mutants of Pseudomonas putida depends on growth medium and phase of growth

Microbiology ◽  
2002 ◽  
Vol 148 (2) ◽  
pp. 537-548 ◽  
Author(s):  
Richard A Lewis ◽  
Colin R Bignell ◽  
Wei Zeng ◽  
Anthony C Jones ◽  
Christopher M Thomas
Keyword(s):  
Cell Division ◽  
Stationary Phase ◽  
Pseudomonas Putida ◽  
Chromosome Segregation ◽  
Copy Number ◽  
Minimal Medium ◽  
Exponential Phase ◽  
Chromosome Loss ◽  
Chromosome Partitioning ◽  
Mutant Phenotypes

The proteins encoded by chromosomal homologues of the parA and parB genes of many bacterial plasmids have been implicated in chromosome partitioning. Unlike their plasmid counterparts, mutant phenotypes produced by deleting these genes have so far been elusive or weakly expressed, except during sporulation. Here the properties of Pseudomonas putida strains with mutations in parA and parB are described. These mutants do not give rise to elevated levels of anucleate bacteria when grown in rich medium under standard conditions. However, in M9-minimal medium different parA and parB mutations gave between 5 and 10% anucleate cells during the transition from exponential phase to stationary phase. Comparison of the DNA content of bacteria at different stages of the growth curve, in batch culture in L-broth and in M9-minimal medium, suggests that the par genes are particularly important for chromosome partitioning when cell division reduces the chromosome copy number per cell from two to one. This transition occurs in P. putida during the entry into stationary phase in M9-minimal medium, but not in L-broth. It is proposed that the partition apparatus is important to ensure proper chromosome segregation primarily when the bacteria are undergoing cell division in the absence of ongoing DNA replication.

scholarly journals Bacterial chromosome segregation.

2005 ◽  
Vol 52 (1) ◽  
pp. 1-34 ◽  
Author(s):  
Aneta A Bartosik ◽  
Grazyna Jagura-Burdzy
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Chromosome Segregation ◽  
Copy Number ◽  
Bacterial Cells ◽  
Replication Machinery ◽  
Rapid Separation ◽  
Dna Segregation ◽  
Low Copy Number ◽  
Bacterial Chromosomes

In most bacteria two vital processes of the cell cycle: DNA replication and chromosome segregation overlap temporally. The action of replication machinery in a fixed location in the cell leads to the duplication of oriC regions, their rapid separation to the opposite halves of the cell and the duplicated chromosomes gradually moving to the same locations prior to cell division. Numerous proteins are implicated in co-replicational DNA segregation and they will be characterized in this review. The proteins SeqA, SMC/MukB, MinCDE, MreB/Mbl, RacA, FtsK/SpoIIIE playing different roles in bacterial cells are also involved in chromosome segregation. The chromosomally encoded ParAB homologs of active partitioning proteins of low-copy number plasmids are also players, not always indispensable, in the segregation of bacterial chromosomes.

scholarly journals Deletion of the parA (soj) Homologue in Pseudomonas aeruginosa Causes ParB Instability and Affects Growth Rate, Chromosome Segregation, and Motility

2007 ◽  
Vol 189 (15) ◽  
pp. 5762-5772 ◽  
Author(s):  
Krzysztof Lasocki ◽  
Aneta A. Bartosik ◽  
Jolanta Mierzejewska ◽  
Christopher M. Thomas ◽  
Grazyna Jagura-Burdzy
Keyword(s):  
Amino Acids ◽  
Growth Rate ◽  
Pseudomonas Aeruginosa ◽  
Stationary Phase ◽  
Chromosome Segregation ◽  
Turnover Rate ◽  
Exponential Phase ◽  
Full Length ◽  
Cytosolic Protein

ABSTRACT The parA and parB genes of Pseudomonas aeruginosa are located approximately 8 kb anticlockwise from oriC. ParA is a cytosolic protein present at a level of around 600 molecules per cell in exponential phase, but the level drops about fivefold in stationary phase. Overproduction of full-length ParA or the N-terminal 85 amino acids severely inhibits growth of P. aeruginosa and P. putida. Both inactivation of parA and overexpression of parA in trans in P. aeruginosa also lead to accumulation of anucleate cells and changes in motility. Inactivation of parA also increases the turnover rate (degradation) of ParB. This may provide a mechanism for controlling the level of ParB in response to the growth rate and expression of the parAB operon.

The role of catalase isozymes in the culturability of the root colonizer Pseudomonas putida after exposure to hydrogen peroxide and antibiotics

1994 ◽  
Vol 40 (5) ◽  
pp. 382-387 ◽  
Author(s):  
Martin G. Klotz ◽  
Anne J. Anderson
Keyword(s):  
Hydrogen Peroxide ◽  
Stationary Phase ◽  
Pseudomonas Putida ◽  
Growth Phase ◽  
Stationary Growth Phase ◽  
Exponential Phase ◽  
Wild Type ◽  
Early Stationary Growth Phase ◽  
Mutant Cells

The culturability of Pseudomonas putida cells after exposure to hydrogen peroxide and antibiotics was correlated with growth-dependent expression of catalase isozymes. Exponential phase wild-type cells, which contained catalase isozyme A, survived a 15-min treatment with less than 4 mM hydrogen peroxide, but were killed by higher concentrations. The culturability of P. putida mutant JIM, which lacked any functional catalase in exponential phase, was reduced by more than 75% after a 15-min exposure to ≥ 0.25 mM hydrogen peroxide. Because submillimolar concentrations of hydrogen peroxide are physiologically relevant in the bacterial cell, our results demonstrate that catalase isozyme A has essential housekeeping functions for growing cultures of P. putida. The accumulation of catalase isozymes B and C during growth into stationary phase coincided with a decrease in the sensitivity of wild-type and JIM cells of P. putida to hydrogen peroxide. Late stationary phase wild-type cells survived a 15-min exposure to even 50 mM hydrogen peroxide and mutant J1M cells survived exposure to 20 mM but not 50 mM hydrogen peroxide. The antibiotics tetracycline and kanamycin, which inhibit protein synthesis, were used to study the role of catalase induction in resistance to hydrogen peroxide. More than 40 and 80% of exponential phase cells of P. putida wild-type and J1M strains, respectively, were rendered nonculturable after a 20-min exposure to 45 μM tetracycline. Surprisingly, stationary phase cells of both P. putida strains were culturable after a 20-min exposure to tetracycline but remained sensitive to kanamycin. Exposure to tetracycline of stationary phase cells did not reduce the resistance of these cells to hydrogen peroxide. Tetracycline but not kanamycin increased the activity of catalase in lysates prepared from P. putida wild-type and mutant cells in early stationary growth phase. At this growth phase, only catalase isozyme B is operational in both strains, which suggests that tetracycline affects the activity of this enzyme.Key words: Pseudomonas putida, antibiotics, catalase, culturability, growth phase.

scholarly journals RocS drives chromosome segregation and nucleoid occlusion in Streptococcus pneumoniae

2018 ◽  
Author(s):  
Chryslène Mercy ◽  
Jean-Pierre Lavergne ◽  
Jelle Slager ◽  
Adrien Ducret ◽  
Pierre Simon Garcia ◽  
...  
Keyword(s):  
Cell Division ◽  
Streptococcus Pneumoniae ◽  
Chromosome Segregation ◽  
Cellular Processes ◽  
Daughter Cells ◽  
Chromosome Partitioning ◽  
Replication Region ◽  
Membrane Bound ◽  
Opportunistic Human Pathogen ◽  
Immune Detection

AbstractSegregation of replicated chromosomes in bacteria is poorly understood outside some prominent model strains and even less is known about how it is coordinated with other cellular processes. Here we report that RocS is crucial for chromosome segregation in the opportunistic human pathogen Streptococcus pneumoniae. RocS is membrane-bound and interacts both with DNA and the chromosome partitioning protein ParB to properly segregate the origin of replication region to new daughter cells. In addition, we show that RocS interacts with the tyrosine-autokinase CpsD required for polysaccharide capsule biogenesis, which is crucial for S. pneumoniae’s ability to prevent host immune detection. Altering the RocS-CpsD interaction drastically hinders chromosome partitioning and cell division. Altogether, this work reveals that RocS is the cornerstone of an atypical nucleoid occlusion system ensuring proper cell division in coordination with the biogenesis of a protective capsular layer.

scholarly journals Role of the C Terminus of FtsK in Escherichia coli Chromosome Segregation

1998 ◽  
Vol 180 (23) ◽  
pp. 6424-6428 ◽  
Author(s):  
Xuan-Chuan Yu ◽  
Elizabeth K. Weihe ◽  
William Margolin
Keyword(s):  
Escherichia Coli ◽  
Cell Division ◽  
Chromosome Segregation ◽  
Null Mutation ◽  
Synthetic Lethal ◽  
Lethal Phenotype ◽  
Chromosome Partitioning ◽  
C Terminus

ABSTRACT FtsK is essential for Escherichia coli cell division. We report that cells lacking the C terminus of FtsK are defective in chromosome segregation as well as septation, often exhibiting asymmetrically positioned nucleoids and large anucleate regions. Combining the corresponding truncated ftsK gene with amukB null mutation resulted in a synthetic lethal phenotype. When the truncated ftsK was combined with aminCDE deletion, chains of minicells were generated, many of which contained DNA. These results suggest that the C terminus of FtsK has an important role in chromosome partitioning.

scholarly journals Adaptation of Mycobacterium smegmatis to Stationary Phase

1999 ◽  
Vol 181 (1) ◽  
pp. 270-283 ◽  
Author(s):  
Marjan J. Smeulders ◽  
Jacquie Keer ◽  
Richard A. Speight ◽  
Huw D. Williams
Keyword(s):  
Cell Division ◽  
Stationary Phase ◽  
Mycobacterium Smegmatis ◽  
Acid Stress ◽  
Exponential Phase ◽  
Quiescent State ◽  
Dependent Manner ◽  
Wild Type ◽  
Glycerol Uptake ◽  
Dynamic Population

ABSTRACT Mycobacterium tuberculosis can persist for many years within host lung tissue without causing clinical disease. Little is known about the state in which the bacilli survive, although it is frequently referred to as dormancy. Some evidence suggests that cells survive in nutrient-deprived stationary phase. Therefore, we are studying stationary-phase survival of Mycobacterium smegmatis as a model for mycobacterial persistence. M. smegmatis cultures could survive 650 days of either carbon, nitrogen, or phosphorus starvation. In carbon-limited medium, cells entered stationary phase before the carbon source (glycerol) had been completely depleted and glycerol uptake from the medium continued during the early stages of stationary phase. These results suggest that the cells are able to sense when the glycerol is approaching limiting concentrations and initiate a shutdown into stationary phase, which involves the uptake of the remaining glycerol from the medium. During early stationary phase, cells underwent reductive cell division and became more resistant to osmotic and acid stress and pool mRNA stabilized. Stationary-phase cells were also more resistant to oxidative stress, but this resistance was induced during late exponential phase in a cell-density-dependent manner. Upon recovery in fresh medium, stationary-phase cultures showed an immediate increase in protein synthesis irrespective of culture age. Colony morphology variants accumulated in stationary-phase cultures. A flat colony variant was seen in 75% of all long-term-stationary-phase cultures and frequently took over the whole population. Cryo scanning electron microscopy showed that the colony organization was different in flat colony strains, flat colonies appearing less well organized than wild-type colonies. Competition experiments with an exponential-phase-adapted wild-type strain showed that the flat strain had a competitive advantage in stationary phase, as well a providing evidence that growth and cell division occur in stationary-phase cultures of M. smegmatis. These results argue against stationary-phase M. smegmatis cultures entering a quiescent state akin to dormancy but support the idea that they are a dynamic population of cells.

scholarly journals The Bifunctional FtsK Protein Mediates Chromosome Partitioning and Cell Division in Caulobacter

2006 ◽  
Vol 188 (4) ◽  
pp. 1497-1508 ◽  
Author(s):  
Sherry C. E. Wang ◽  
Lisandra West ◽  
Lucy Shapiro
Keyword(s):  
Cell Division ◽  
Chromosome Segregation ◽  
Caulobacter Crescentus ◽  
Topoisomerase Iv ◽  
Division Plane ◽  
Cellular Processes ◽  
Chromosome Partitioning ◽  
C Terminus ◽  
N Terminus ◽  
Necessary And Sufficient

ABSTRACT Bacterial chromosome partitioning and cell division are tightly connected cellular processes. We show here that the Caulobacter crescentus FtsK protein localizes to the division plane, where it mediates multiple functions involved in chromosome segregation and cytokinesis. The first 258 amino acids of the N terminus are necessary and sufficient for targeting the protein to the division plane. Furthermore, the FtsK N terminus is required to either assemble or maintain FtsZ rings at the division plane. The FtsK C terminus is essential in Caulobacter and is involved in maintaining accurate chromosome partitioning. In addition, the C-terminal region of FtsK is required for the localization of the topoisomerase IV ParC subunit to the replisome to facilitate chromosomal decatenation prior to cell division. These results suggest that the interdependence between chromosome partitioning and cell division in Caulobacter is mediated, in part, by the FtsK protein.

scholarly journals Involvement of Cyclopropane Fatty Acids in the Response of Pseudomonas putida KT2440 to Freeze-Drying

2006 ◽  
Vol 72 (1) ◽  
pp. 472-477 ◽  
Author(s):  
Jesús Muñoz-Rojas ◽  
Patricia Bernal ◽  
Estrella Duque ◽  
Patricia Godoy ◽  
Ana Segura ◽  
...  
Keyword(s):  
Stationary Phase ◽  
Pseudomonas Putida ◽  
Freeze Drying ◽  
Plant Root ◽  
Survival Rates ◽  
Exponential Phase ◽  
Pseudomonas Putida Kt2440 ◽  
Long Term Storage ◽  
Foreign Genes ◽  
A Minor

ABSTRACT Pseudomonas putida KT2440, a saprophytic soil bacterium that colonizes the plant root, is a suitable microorganism for the removal of pollutants and a stable host for foreign genes used in biotransformation processes. Because of its potential use in agriculture and industry, we investigated the conditions for the optimal preservation of the strain and its derivatives for long-term storage. The highest survival rates were achieved with cells that had reached the stationary phase and which had been subjected to freeze-drying in the presence of disaccharides (trehalose, maltose, and lactose) as lyoprotectants. Using fluorescence polarization techniques, we show that cell membranes of KT2440 were more rigid in the stationary phase than in the exponential phase of growth. This is consistent with the fact that cells grown in the stationary phase exhibited a higher proportion of C17:cyclopropane as a fatty acid than cells in the exponential phase. Mutants for the cfaB gene, which encodes the main C17:cyclopropane synthase, and for the cfaA gene, which encodes a minor C17:cyclopropane synthase, were constructed. These mutants were more sensitive to freeze-drying than wild-type cells, particularly the mutant with a knockout in the cfaB gene that produced less than 2% of the amount of C17:cyclopropane produced by the parental strain.

Morphological Characterization of Mycobacteriophage R1

1974 ◽  
Vol 32 ◽  
pp. 254-255
Author(s):  
B. L. Soloff ◽  
T. A. Rado
Keyword(s):  
Carbon Source ◽  
Stationary Phase ◽  
Growth Phase ◽  
Minimal Medium ◽  
Morphological Characterization ◽  
Logarithmic Growth Phase ◽  
Complete Lysis ◽  
Lysogenic Culture ◽  
Logarithmic Growth

Mycobacteriophage R1 was originally isolated from a lysogenic culture of M. butyricum. The virus was propagated on a leucine-requiring derivative of M. smegmatis, 607 leu−, isolated by nitrosoguanidine mutagenesis of typestrain ATCC 607. Growth was accomplished in a minimal medium containing glycerol and glucose as carbon source and enriched by the addition of 80 μg/ ml L-leucine. Bacteria in early logarithmic growth phase were infected with virus at a multiplicity of 5, and incubated with aeration for 8 hours. The partially lysed suspension was diluted 1:10 in growth medium and incubated for a further 8 hours. This permitted stationary phase cells to re-enter logarithmic growth and resulted in complete lysis of the culture.

scholarly journals The Role of Cdh1p in Maintaining Genomic Stability in Budding Yeast

Genetics ◽  
2003 ◽  
Vol 165 (2) ◽  
pp. 489-503 ◽  
Author(s):  
Karen E Ross ◽  
Orna Cohen-Fix
Keyword(s):  
Cell Cycle ◽  
Chromosome Segregation ◽  
Spindle Assembly Checkpoint ◽  
Chromosome Loss ◽  
Cyclin Dependent Kinase ◽  
Anaphase Promoting Complex ◽  
Growth Defects ◽  
Genes Encoding ◽  
Specificity Factor

Abstract Cdh1p, a substrate specificity factor for the cell cycle-regulated ubiquitin ligase, the anaphase-promoting complex/cyclosome (APC/C), promotes exit from mitosis by directing the degradation of a number of proteins, including the mitotic cyclins. Here we present evidence that Cdh1p activity at the M/G1 transition is important not only for mitotic exit but also for high-fidelity chromosome segregation in the subsequent cell cycle. CDH1 showed genetic interactions with MAD2 and PDS1, genes encoding components of the mitotic spindle assembly checkpoint that acts at metaphase to prevent premature chromosome segregation. Unlike cdh1Δ and mad2Δ single mutants, the mad2Δ cdh1Δ double mutant grew slowly and exhibited high rates of chromosome and plasmid loss. Simultaneous deletion of PDS1 and CDH1 caused extensive chromosome missegregation and cell death. Our data suggest that at least part of the chromosome loss can be attributed to kinetochore/spindle problems. Our data further suggest that Cdh1p and Sic1p, a Cdc28p/Clb inhibitor, have overlapping as well as nonoverlapping roles in ensuring proper chromosome segregation. The severe growth defects of both mad2Δ cdh1Δ and pds1Δ cdh1Δ strains were rescued by overexpressing Swe1p, a G2/M inhibitor of the cyclin-dependent kinase, Cdc28p/Clb. We propose that the failure to degrade cyclins at the end of mitosis leaves cdh1Δ mutant strains with abnormal Cdc28p/Clb activity that interferes with proper chromosome segregation.

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