scholarly journals THE ROLE OF RADIATION (rad) GENES IN MEIOTIC RECOMBINATION IN YEAST

Genetics ◽  
1980 ◽  
Vol 94 (1) ◽  
pp. 51-68
Author(s):  
J C Game ◽  
T J Zamb ◽  
R J Braun ◽  
M Resnick ◽  
R M Roth
Keyword(s):  
Dna Replication ◽  
Dna Synthesis ◽  
Gene Conversion ◽  
Mitotic Cell ◽  
Intragenic Recombination ◽  
Cell Cycles ◽  
Normal Functions ◽  
Rad Genes ◽  
Radiation Repair

ABSTRACT In yeast, the functions controlled by radiation-repair genes RAD6, RAD50, RAD52 and RAD57 are essential for normal meiosis; diploids with lesions in these genes either fail to sporulate (rad6) or sporulate but produce inviable spores (rad50, 52, 57). Since RAD genes may control aspects of DNA metabolism, we attempted to define more precisely the role of each gene in meiosis, especially with regard to possible roles in premeiotic DNA replication and recombination. We constructed diploids singly homozygous for each of the four rad mutations, heteroallelic at his1 and heterozygous for a recessive canavanine-resistance marker. Each strain was exposed to sporulation-inducing conditions and monitored for (1) completion of mitotic cell cycles, (2) cell viability, (3)utilization of acetate for mass increases, (4)premeiotic DNA synthesis, (5) intragenic recombination at his1, and (6) formation of viable haploid spores. Control strains heterozygous for the rad mutations completed mitosis, metabolized acetate, replicated their DNA, and showed typically high levels of gene conversion and viable-spore formation. The mutant diploids also completed mitosis, utilized acetate, and carried out premeiotic DNA replication. The mutants, however, showed little or no meiotic gene conversion. The rad50, 52 and 57 strains sporulated, but the spores were inviable. The rad6 strain did not sporulate. The rad50, 52 and 57 strains exhibited viability losses that co-incided with the period of DNA synthesis, but not with later meiotic events; the rad6 strain did not lose viability. We propose that the normal functions specified by RAD50,52 and 57 are not essential for either the initial or terminal steps in meiosis, but are required for successful recombination. The rad6 strain may be recombination-defective, o r it may fail to progress past DNA replication in the overall sequence leading to formation and recovery of meiotic recombinants.

scholarly journals Computational modelling of chromosome re-replication in mutant strains of fission yeast

2020 ◽  
Author(s):  
Béla Novák ◽  
John J Tyson
Keyword(s):  
Dna Replication ◽  
Fission Yeast ◽  
Computational Modelling ◽  
Mitotic Cell ◽  
Cyclin Dependent Kinase ◽  
Slow Increase ◽  
Cell Cycles ◽  
Mitotic Cyclin ◽  
The Mathematical Model ◽  
Insight Into

AbstractTypically cells replicate their genome only once per division cycle, but under some circumstances, both natural and unnatural, cells synthesize an overabundance of DNA, either in a disorganized fashion (‘over-replication’) or by a systematic doubling of chromosome number (‘endoreplication’). These variations on the theme of DNA replication and division have been studied in strains of fission yeast, Schizosaccharomyces pombe, carrying mutations that interfere with the function of mitotic cyclin-dependent kinase (Cdk1:Cdc13) without impeding the roles of DNA-replication licensing factor (Cdc18) and S-phase cyclin-dependent kinase (Cdk1:Cig2). Some of these mutations support endoreplication, and some over-replication. In this paper, we propose a dynamical model of the interactions among the proteins governing DNA replication and cell division in fission yeast. By computational simulations of the mathematical model, we account for the observed phenotypes of these re-replicating mutants, and by theoretical analysis of the dynamical system, we provide insight into the molecular distinctions between over-replicating and endoreplicating cells. In case of induced over-production of regulatory proteins, our model predicts that cells first switch from normal mitotic cell cycles to growth-controlled endoreplication, and ultimately to disorganized over-replication, parallel to the slow increase of protein to very high levels.

scholarly journals A dependent pathway of gene functions leading to chromosome segregation in Saccharomyces cerevisiae.

1982 ◽  
Vol 94 (3) ◽  
pp. 718-726 ◽  
Author(s):  
J S Wood ◽  
L H Hartwell
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Chromosome Segregation ◽  
Nuclear Division ◽  
Mitotic Cell ◽  
Mitotic Cell Cycle ◽  
Gene Products ◽  
Dependent Pathway

Methyl-benzimidazole-2-ylcarbamate (MBC) inhibits the mitotic cell cycle of Saccharomyces cerevisiae at a stage subsequent to DNA synthesis and before the completion of nuclear division (Quinlan, R. A., C. I. Pogson, and K, Gull, 1980, J Cell Sci., 46: 341-352). The step in the cell cycle that is sensitive to MBC inhibition was ordered to reciprocal shift experiments with respect to the step catalyzed by cdc gene products. Execution of the CDC7 step is required for the initiation of DNA synthesis and for completion of the MBC-sensitive step. Results obtained with mutants (cdc2, 6, 8, 9, and 21) defective in DNA replication and with an inhibitor of DNA replication (hydroxyurea) suggest that some DNA replication required for execution of the MBC-sensitive step but that the completion of replication is not. Of particular interest were mutants (cdc5, 13, 14, 15, 16, 17, and 23) that arrest cell division after DNA replication but before nuclear division since previous experiments had not been able to resolve the pathway of events in this part of the cell cycle. Execution of the CDC17 step was found to be a prerequisite for execution of the MBC-sensitive step; the CDC13, 16 and 23 steps are executed independently of the MBC-sensitive step; execution of the MBC-sensitive step is prerequisite for execution of the MBC-sensitive step; execution of the MBC-sensitive step is prerequisite for execution of the CDC14 and 23 steps. These results considerably extend the dependent pathway of events that constitute the cell cycle of S. cerevisiae.

Inhibition of cysteine protease activity disturbs DNA replication and prevents mitosis in the early mitotic cell cycles of sea urchin embryos

2005 ◽  
Vol 204 (2) ◽  
pp. 693-703 ◽  
Author(s):  
Carolina Concha ◽  
Antonia Monardes ◽  
Yasmine Even ◽  
Violeta Morin ◽  
Marcia Puchi ◽  
...  
Keyword(s):  
Dna Replication ◽  
Sea Urchin ◽  
Cysteine Protease ◽  
Protease Activity ◽  
Mitotic Cell ◽  
Cell Cycles ◽  
Sea Urchin Embryos ◽  
Cysteine Protease Activity

scholarly journals Involvement of the essential yeast DNA polymerases in induced gene conversion.

1999 ◽  
Vol 46 (4) ◽  
pp. 862-872 ◽  
Author(s):  
A Hałas ◽  
A Ciesielski ◽  
J Zuk
Keyword(s):  
Dna Synthesis ◽  
Gene Conversion ◽  
Dna Polymerase ◽  
Dna Polymerases ◽  
Yeast Saccharomyces Cerevisiae ◽  
Dna Polymerase Alpha ◽  
Genes Encoding ◽  
Mitotic Gene Conversion ◽  
Dna Strand

In the yeast Saccharomyces cerevisiae three different DNA polymerases alpha, delta and epsilon are involved in DNA replication. DNA polymerase alpha is responsible for initiation of DNA synthesis and polymerases delta and epsilon are required for elongation of DNA strand during replication. DNA polymerases delta and epsilon are also involved in DNA repair. In this work we studied the role of these three DNA polymerases in the process of recombinational synthesis. Using thermo-sensitive heteroallelic mutants in genes encoding DNA polymerases we studied their role in the process of induced gene conversion. Mutant strains were treated with mutagens, incubated under permissive or restrictive conditions and the numbers of convertants obtained were compared. A very high difference in the number of convertants between restrictive and permissive conditions was observed for polymerases alpha and delta, which suggests that these two polymerases play an important role in DNA synthesis during mitotic gene conversion. Marginal dependence of gene conversion on the activity of polymerase epsilon indicates that this DNA polymerase may be involved in this process but rather as an auxiliary enzyme.

scholarly journals Role of p38 in Replication of Trypanosoma brucei Kinetoplast DNA

2006 ◽  
Vol 26 (14) ◽  
pp. 5382-5393 ◽  
Author(s):  
Beiyu Liu ◽  
Henrik Molina ◽  
Dario Kalume ◽  
Akhilesh Pandey ◽  
Jack D. Griffith ◽  
...  
Keyword(s):  
Rna Interference ◽  
Dna Replication ◽  
Mitochondrial Genome ◽  
Dna Synthesis ◽  
Trypanosoma Brucei ◽  
Replication Origin ◽  
Mitochondrial Protein ◽  
Kinetoplast Dna ◽  
Z Dna

ABSTRACT Trypanosomes have an unusual mitochondrial genome, called kinetoplast DNA, that is a giant network containing thousands of interlocked minicircles. During kinetoplast DNA synthesis, minicircles are released from the network for replication as θ-structures, and then the free minicircle progeny reattach to the network. We report that a mitochondrial protein, which we term p38, functions in kinetoplast DNA replication. RNA interference (RNAi) of p38 resulted in loss of kinetoplast DNA and accumulation of a novel free minicircle species named fraction S. Fraction S minicircles are so underwound that on isolation they become highly negatively supertwisted and develop a region of Z-DNA. p38 binds to minicircle sequences within the replication origin. We conclude that cells with RNAi-induced loss of p38 cannot initiate minicircle replication, although they can extensively unwind free minicircles.

scholarly journals A novel recombinator in yeast based on gene II protein from bacteriophage f1.

Genetics ◽  
1991 ◽  
Vol 127 (1) ◽  
pp. 61-73 ◽  
Author(s):  
J N Strathern ◽  
K G Weinstock ◽  
D R Higgins ◽  
C B McGill
Keyword(s):  
Dna Replication ◽  
Gene Conversion ◽  
Mitotic Recombination ◽  
Recognition Site ◽  
Directional Bias ◽  
Site Specific ◽  
Origin Of Dna Replication ◽  
A Site ◽  
Stimulation Of

Abstract Interchromosomal mitotic recombination in yeast can be stimulated by the protein encoded by gene II of bacteriophage f1. The normal role of the gene II enzyme is to make a site-specific cleavage of a particular strand of the duplex form of the bacteriophage DNA at the origin of DNA replication. The gene II protein was expressed in yeast in an attempt to determine the role of nicked DNA in the initiation of recombination. Stimulation of recombination in yeast by the gene II protein was dependent on the presence of a recognition site for gene II enzyme in the region being assayed. Recombination was stimulated in both directions from the gene II recognition site but showed a directional bias. The distribution of alleles among the recombinants indicated that the chromosome with the gene II recognition site acted as the recipient in gene conversion events.

scholarly journals Cdc28 and Ime2 Possess Redundant Functions in Promoting Entry Into Premeiotic DNA Replication in Saccharomyces cerevisiae

Genetics ◽  
2001 ◽  
Vol 159 (4) ◽  
pp. 1547-1558
Author(s):  
Noga Guttmann-Raviv ◽  
Elisabeth Boger-Nadjar ◽  
Iris Edri ◽  
Yona Kassir
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Replication ◽  
Meiotic Recombination ◽  
Mitotic Cell ◽  
Temperature Sensitive ◽  
Cyclin Dependent Kinase ◽  
Yeast Saccharomyces Cerevisiae ◽  
Redundant Functions ◽  
Meiotic Cycle

Abstract In the budding yeast Saccharomyces cerevisiae initiation and progression through the mitotic cell cycle are determined by the sequential activity of the cyclin-dependent kinase Cdc28. The role of this kinase in entry and progression through the meiotic cycle is unclear, since all cdc28 temperature-sensitive alleles are leaky for meiosis. We used a “heat-inducible Degron system” to construct a diploid strain homozygous for a temperature-degradable cdc28-deg allele. We show that this allele is nonleaky, giving no asci at the nonpermissive temperature. We also show, using this allele, that Cdc28 is not required for premeiotic DNA replication and commitment to meiotic recombination. IME2 encodes a meiosis-specific hCDK2 homolog that is required for the correct timing of premeiotic DNA replication, nuclear divisions, and asci formation. Moreover, in ime2Δ diploids additional rounds of DNA replication and nuclear divisions are observed. We show that the delayed premeiotic DNA replication observed in ime2Δ diploids depends on a functional Cdc28. Ime2Δ cdc28-4 diploids arrest prior to initiation of premeiotic DNA replication and meiotic recombination. Ectopic overexpression of Clb1 at early meiotic times advances premeiotic DNA replication, meiotic recombination, and nuclear division, but the coupling between these events is lost. The role of Ime2 and Cdc28 in initiating the meiotic pathway is discussed.

scholarly journals Essential Role of MCM Proteins in Premeiotic DNA Replication

2002 ◽  
Vol 13 (2) ◽  
pp. 435-444 ◽  
Author(s):  
Karola Lindner ◽  
Juraj Gregán ◽  
Stuart Montgomery ◽  
Stephen E. Kearsey
Keyword(s):  
Dna Replication ◽  
S Phase ◽  
Yeast Cells ◽  
Critical Event ◽  
Minichromosome Maintenance ◽  
Cell Cycles ◽  
Eukaryotic Dna ◽  
Mcm Proteins ◽  
Meiotic Cycle

A critical event in eukaryotic DNA replication involves association of minichromosome maintenance (MCM2–7) proteins with origins, to form prereplicative complexes (pre-RCs) that are competent for initiation. The ability of mutants defective in MCM2–7 function to complete meiosis had suggested that pre-RC components could be irrelevant to premeiotic S phase. We show here that MCM2–7 proteins bind to chromatin in fission yeast cells preparing for meiosis and during premeiotic S phase in a manner suggesting they in fact are required for DNA replication in the meiotic cycle. This is confirmed by analysis of a degron mcm4 mutant, which cannot carry out premeiotic DNA replication. Later in meiosis, Mcm4 chromatin association is blocked between meiotic nuclear divisions, presumably accounting for the absence of a second round of DNA replication. Together, these results emphasize similarity between replication mechanisms in mitotic and meiotic cell cycles.

scholarly journals DNA polymerases ν and θ are required for efficient immunoglobulin V gene diversification in chicken

2010 ◽  
Vol 189 (7) ◽  
pp. 1117-1127 ◽  
Author(s):  
Masaoki Kohzaki ◽  
Kana Nishihara ◽  
Kouji Hirota ◽  
Eiichiro Sonoda ◽  
Michio Yoshimura ◽  
...  
Keyword(s):  
Dna Synthesis ◽  
Gene Conversion ◽  
B Lymphocyte ◽  
Dna Polymerases ◽  
Point Mutations ◽  
Triple Mutant ◽  
Translesion Dna Synthesis ◽  
Gene Diversification ◽  
V Genes

The chicken DT40 B lymphocyte line diversifies its immunoglobulin (Ig) V genes through translesion DNA synthesis–dependent point mutations (Ig hypermutation) and homologous recombination (HR)–dependent Ig gene conversion. The error-prone biochemical characteristic of the A family DNA polymerases Polν and Polθ led us to explore the role of these polymerases in Ig gene diversification in DT40 cells. Disruption of both polymerases causes a significant decrease in Ig gene conversion events, although POLN−/−/POLQ−/− cells exhibit no prominent defect in HR-mediated DNA repair, as indicated by no increase in sensitivity to camptothecin. Polη has also been previously implicated in Ig gene conversion. We show that a POLH−/−/POLN−/−/POLQ−/− triple mutant displays no Ig gene conversion and reduced Ig hypermutation. Together, these data define a role for Polν and Polθ in recombination and suggest that the DNA synthesis associated with Ig gene conversion is accounted for by three specialized DNA polymerases.

Sign in / Sign up

Export Citation Format

Share Document