scholarly journals Spo0J and SMC are required for normal chromosome segregation in Staphylococcus aureus

2020 ◽  
Vol 9 (4) ◽  
Author(s):  
Helena Chan ◽  
Bill Söderström ◽  
Ulf Skoglund
Keyword(s):  
Staphylococcus Aureus ◽  
Chromosome Segregation ◽  
Normal Chromosome

scholarly journals Phase separation of Polo-like kinase 4 by autoactivation and clustering drives centriole biogenesis

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Jung-Eun Park ◽  
Liang Zhang ◽  
Jeong Kyu Bang ◽  
Thorkell Andresson ◽  
Frank DiMaio ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Separation ◽  
Symmetry Breaking ◽  
Genomic Instability ◽  
Chromosome Segregation ◽  
Genomic Stability ◽  
Normal Chromosome ◽  
Tight Control ◽  
Centriole Duplication ◽  
Disordered Loop

Abstract Tight control of centriole duplication is critical for normal chromosome segregation and the maintenance of genomic stability. Polo-like kinase 4 (Plk4) is a key regulator of centriole biogenesis. How Plk4 dynamically promotes its symmetry-breaking relocalization and achieves its procentriole-assembly state remains unknown. Here we show that Plk4 is a unique kinase that utilizes its autophosphorylated noncatalytic cryptic polo-box (CPB) to phase separate and generate a nanoscale spherical condensate. Analyses of the crystal structure of a phospho-mimicking, condensation-proficient CPB mutant reveal that a disordered loop at the CPB PB2-tip region is critically required for Plk4 to generate condensates and induce procentriole assembly. CPB phosphorylation also promotes Plk4’s dissociation from the Cep152 tether while binding to downstream STIL, thus allowing Plk4 condensate to serve as an assembling body for centriole biogenesis. This study uncovers the mechanism underlying Plk4 activation and may offer strategies for anti-Plk4 intervention against genomic instability and cancer.

scholarly journals HIM-17 regulates the position of recombination events and GSP-1/2 localization to establish short arm identity on bivalents in meiosis

2021 ◽  
Vol 118 (17) ◽  
pp. e2016363118
Author(s):  
Saravanapriah Nadarajan ◽  
Elisabeth Altendorfer ◽  
Takamune T. Saito ◽  
Marina Martinez-Garcia ◽  
Monica P. Colaiácovo
Keyword(s):  
Chromosome Segregation ◽  
Normal Chromosome ◽  
Early Prophase ◽  
Dna Double Strand Breaks ◽  
Late Prophase ◽  
Strand Breaks ◽  
Meiotic Progression ◽  
Prophase I ◽  
Chromatid Cohesion ◽  
Normal Expression

The position of recombination events established along chromosomes in early prophase I and the chromosome remodeling that takes place in late prophase I are intrinsically linked steps of meiosis that need to be tightly regulated to ensure accurate chromosome segregation and haploid gamete formation. Here, we show that RAD-51 foci, which form at the sites of programmed meiotic DNA double-strand breaks (DSBs), exhibit a biased distribution toward off-centered positions along the chromosomes in wild-type Caenorhabditis elegans, and we identify two meiotic roles for chromatin-associated protein HIM-17 that ensure normal chromosome remodeling in late prophase I. During early prophase I, HIM-17 regulates the distribution of DSB-dependent RAD-51 foci and crossovers on chromosomes, which is critical for the formation of distinct chromosome subdomains (short and long arms of the bivalents) later during chromosome remodeling. During late prophase I, HIM-17 promotes the normal expression and localization of protein phosphatases GSP-1/2 to the surface of the bivalent chromosomes and may promote GSP-1 phosphorylation, thereby antagonizing Aurora B kinase AIR-2 loading on the long arms and preventing premature loss of sister chromatid cohesion. We propose that HIM-17 plays distinct roles at different stages during meiotic progression that converge to promote normal chromosome remodeling and accurate chromosome segregation.

Kinesinsklp5+ andklp6+ are required for normal chromosome movement in mitosis

2002 ◽  
Vol 115 (5) ◽  
pp. 931-940 ◽  
Author(s):  
Robert R. West ◽  
Terra Malmstrom ◽  
J. Richard McIntosh
Keyword(s):  
Chromosome Segregation ◽  
Spindle Assembly Checkpoint ◽  
Extended Period ◽  
Normal Chromosome ◽  
Chromosome Movement ◽  
Dynamic Interactions ◽  
Spindle Elongation ◽  
Synthetically Lethal ◽  
Anaphase B ◽  
Null Mutants

Proper mitotic chromosome segregation requires dynamic interactions between spindle microtubules and kinetochores. Here we demonstrate that two related fission yeast kinesins, klp5+ and klp6+, are required for normal chromosome segregation in mitosis. Null mutants frequently lack a normal metaphase chromosome alignment. Chromosome pairs move back and forth along the spindle for an extended period prior to sister chromatid separation, a phenotype reminiscent of the loss of CENP-E in metazoans. Ultimately, sister chromatids segregate, regardless of chromosome position along the spindle, and viable daughter cells are usually produced. The initiation of anaphase B is sometimes delayed, but the rate of spindle elongation is similar to wildtype. Despite a delay, anaphase B often begins before anaphase A is completed. The klp5Δ and klp6Δ null mutants are synthetically lethal with a deletion of the spindle assembly checkpoint gene, bub1+, several mutants in components of the anaphase promoting complex, and a cold sensitive allele of the kinetochore and microtubule-binding protein, Dis1p. Klp5p-GFP and Klp6p-GFP localize to kinetochores from prophase to the onset of anaphase A, but relocalize to the spindle midzone during anaphase B. These data indicate that Klp5p and Klp6p are kinetochore kinesins required for normal chromosome movement in prometaphase.

scholarly journals Contribution of SMC (Structural Maintenance of Chromosomes) and SpoIIIE to Chromosome Segregation in Staphylococci

2010 ◽  
Vol 192 (15) ◽  
pp. 4067-4073 ◽  
Author(s):  
Wenqi Yu ◽  
Silvia Herbert ◽  
Peter L. Graumann ◽  
Friedrich Götz
Keyword(s):  
Staphylococcus Aureus ◽  
Chromosome Segregation ◽  
Chromosome Dynamics ◽  
Chromosomal Segregation ◽  
Structural Maintenance Of Chromosomes

ABSTRACT In contrast to rod-shaped bacteria, little is known about chromosomal maintenance and segregation in the spherical Staphylococcus aureus. The analysis of chromosomal segregation in smc (structural maintenance of chromosomes) and spoIIIE single and double mutants unravels differences in the chromosome dynamics in the spherical staphylococcal cells compared to the model in rods.

scholarly journals Release of Mps1 from kinetochores is crucial for timely anaphase onset

2010 ◽  
Vol 191 (2) ◽  
pp. 281-290 ◽  
Author(s):  
Nannette Jelluma ◽  
Tobias B. Dansen ◽  
Tale Sliedrecht ◽  
Nicholas P. Kwiatkowski ◽  
Geert J.P.L. Kops
Keyword(s):  
Error Correction ◽  
Chromosome Segregation ◽  
Kinase Activity ◽  
Mitotic Checkpoint ◽  
Normal Chromosome ◽  
Half Time ◽  
Anaphase Onset ◽  
Chromosome Attachment

Mps1 kinase activity is required for proper chromosome segregation during mitosis through its involvements in microtubule–chromosome attachment error correction and the mitotic checkpoint. Mps1 dynamically exchanges on unattached kinetochores but is largely removed from kinetochores in metaphase. Here we show that Mps1 promotes its own turnover at kinetochores and that removal of Mps1 upon chromosome biorientation is a prerequisite for mitotic checkpoint silencing. Inhibition of Mps1 activity increases its half-time of recovery at unattached kinetochores and causes accumulation of Mps1 protein at these sites. Strikingly, preventing dissociation of active Mps1 from kinetochores delays anaphase onset despite normal chromosome attachment and alignment, and high interkinetochore tension. This delay is marked by continued recruitment of Mad1 and Mad2 to bioriented chromosomes and is attenuated by Mad2 depletion, indicating chronic engagement of the mitotic checkpoint in metaphase. We propose that release of Mps1 from kinetochores is essential for mitotic checkpoint silencing and a fast metaphase-to-anaphase transition.

scholarly journals CHROMOSOME MICROMANIPULATION

1969 ◽  
Vol 43 (1) ◽  
pp. 40-50 ◽  
Author(s):  
R. Bruce Nicklas ◽  
Carol A. Koch
Keyword(s):  
Chromosome Segregation ◽  
Normal Chromosome ◽  
Chromosome Distribution ◽  
Critical Process ◽  
Spindle Fibers

Kinetochore reorientation is the critical process ensuring normal chromosome distribution. Reorientation has been studied in living grasshopper spermatocytes, in which bivalents with both chromosomes oriented to the same pole (unipolar orientation) occur but are unstable: sooner or later one chromosome reorients, the stable, bipolar orientation results, and normal anaphase segregation to opposite poles follows. One possible source of stability in bipolar orientations is the normal spindle forces toward opposite poles, which slightly stretch the bivalent. This tension is lacking in unipolar orientations because all the chromosomal spindle fibers and spindle forces are directed toward one pole. The possible role of tension has been tested directly by micromanipulation of bivalents in unipolar orientation to artificially create the missing tension. Without exception, such bivalents never reorient before the tension is released; a total time "under tension" of over 5 hr has been accumulated in experiments on eight bivalents in eight cells. In control experiments these same bivalents reoriented from a unipolar orientation within 16 min, on the average, in the absence of tension. Controlled reorientation and chromosome segregation can be explained from the results of these and related experiments.

scholarly journals Meiotic disjunction of homologs in Saccharomyces cerevisiae is directed by pairing and recombination of the chromosome arms but not by pairing of the centromeres.

Genetics ◽  
1988 ◽  
Vol 119 (2) ◽  
pp. 273-287
Author(s):  
R T Surosky ◽  
B K Tye
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chromosome Segregation ◽  
Meiotic Chromosome ◽  
Chromosomal Rearrangements ◽  
Normal Chromosome ◽  
Telocentric Chromosome ◽  
Meiotic Chromosomes ◽  
Chromosome Recombination ◽  
Left And Right ◽  
Chromosome Iii

Abstract We explored the behavior of meiotic chromosomes in Saccharomyces cerevisiae by examining the effects of chromosomal rearrangements on the pattern of disjunction and recombination of chromosome III during meiosis. The segregation of deletion chromosomes lacking part or all (telocentric) of one arm was analyzed in the presence of one or two copies of a normal chromosome III. In strains containing one normal and any one deletion chromosome, the two chromosomes disjoined in most meioses. In strains with one normal chromosome and both a left and right arm telocentric chromosome, the two telocentrics preferentially disjoined from the normal chromosome. Homology on one arm was sufficient to direct chromosome disjunction, and two chromosomes could be directed to disjoin from a third. In strains containing one deletion chromosome and two normal chromosomes, the two normal chromosomes preferentially disjoined, but in 4-7% of the tetrads the normal chromosomes cosegregated, disjoining from the deletion chromosome. Recombination between the two normal chromosomes or between the deletion chromosome and a normal chromosome increased the probability that these chromosomes would disjoin, although cosegregation of recombinants was observed. Finally, we observed that a derivative of chromosome III in which the centromeric region was deleted and CEN5 was integrated at another site on the chromosome disjoined from a normal chromosome III with fidelity. These studies demonstrate that it is not pairing of the centromeres, but pairing and recombination along the arms of the homologs, that directs meiotic chromosome segregation.

scholarly journals Coordination of Chromosome Segregation and Cell Division in Staphylococcus aureus

2017 ◽  
Vol 8 ◽  
Author(s):  
Amy L. Bottomley ◽  
Andrew T. F. Liew ◽  
Kennardy D. Kusuma ◽  
Elizabeth Peterson ◽  
Lisa Seidel ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Division ◽  
Chromosome Segregation
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