scholarly journals A Saccharomyces cerevisiae RAD52 allele expressing a C-terminal truncation protein: activities and intragenic complementation of missense mutations.

Genetics ◽  
1993 ◽  
Vol 133 (1) ◽  
pp. 39-49 ◽  
Author(s):  
K L Boundy-Mills ◽  
D M Livingston
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Repair ◽  
Deletion Mutants ◽  
Crossing Over ◽  
Missense Mutations ◽  
Wild Type ◽  
Spore Viability ◽  
Deletion Allele ◽  
Low Level ◽  
Intragenic Complementation

Abstract A nonsense allele of the yeast RAD52 gene, rad52-327, which expresses the N-terminal 65% of the protein was compared to two missense alleles, rad52-1 and rad52-2, and to a deletion allele. While the rad52-1 and the deletion mutants have severe defects in DNA repair, recombination and sporulation, the rad52-327 and rad52-2 mutants retain either partial or complete capabilities in repair and recombination. These two mutants behave similarly in most tests of repair and recombination during mitotic growth. One difference between these two alleles is that a homozygous rad52-2 diploid fails to sporulate, whereas the homozygous rad52-327 diploid sporulates weakly. The low level of sporulation by the rad52-327 diploid is accompanied by a low percentage of spore viability. Among these viable spores the frequency of crossing over for markers along chromosome VII is the same as that found in wild-type spores. rad52-327 complements rad52-2 for repair and sporulation. Weaker intragenic complementation occurs between rad52-327 and rad52-1.

scholarly journals Analysis of mitotic and meiotic defects in Saccharomyces cerevisiae SRS2 DNA helicase mutants.

Genetics ◽  
1992 ◽  
Vol 132 (1) ◽  
pp. 23-37 ◽  
Author(s):  
F Palladino ◽  
H L Klein
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Helicase ◽  
Missense Mutations ◽  
Spore Viability ◽  
Mutational Change ◽  
Uv Sensitivity ◽  
Helicase Gene ◽  
Definition Of ◽  
Gene Variability ◽  
New Alleles

Abstract The hyper-gene conversion srs2-101 mutation of the SRS2 DNA helicase gene of Saccharomyces cerevisiae has been reported to suppress the UV sensitivity of rad18 mutants. New alleles of SRS2 were recovered using this suppressor phenotype. The alleles have been characterized with respect to suppression of rad18 UV sensitivity, hyperrecombination, reduction of meiotic viability, and definition of the mutational change within the SRS2 gene. Variability in the degree of rad18 suppression and hyperrecombination were found. The alleles that showed the severest effects were found to be missense mutations within the consensus domains of the DNA helicase family of proteins. The effect of mutations in domains I (ATP-binding) and V (proposed DNA binding) are reported. Some alleles of SRS2 reduce spore viability to 50% of wild-type levels. This phenotype is not bypassed by spo13 mutation. Although the srs2 homozygous diploids strains undergo normal commitment to meiotic recombination, this event is delayed by several hours in the mutant strains and the strains appear to stall in the progression from meiosis I to meiosis II.

scholarly journals Low-Power Red and Infrared Laser Effects on Cells Deficient in DNA Repair

2019 ◽  
Vol 10 (3) ◽  
pp. 157-162
Author(s):  
Lucas Kiyoshi da Fonseca Iwahara ◽  
Flavia de Paoli ◽  
Adenilson de Souza da Fonseca
Keyword(s):  
Escherichia Coli ◽  
Dna Repair ◽  
Low Power ◽  
Cell Viability ◽  
Bacterial Cells ◽  
Wild Type ◽  
Low Level ◽  
Affect Cell Viability ◽  
Study Results ◽  
Emission Mode

Introduction: Low-level lasers are successfully used to prevent and treat diseases in soft oral and bone tissues, particularly diseases in oral cavity caused by chemotherapy and radiotherapy in oncology. However, controversy exists as to whether these lasers induce molecular side effects, mainly on DNA. The aim of this work was to assess the effects of low-power lasers on mutant Escherichia coli cells in DNA repair. Methods: Escherichia coli wild type cultures as well as those lacking recombination DNA repair (recA- ) and la SOS responses (lexA- ) irradiated with lasers at different energy densities, powers, and emission modes for cell viability and morphology assessment were used in this study. Results: Laser irradiation: (i) did not affect cell viability of non-mutant and lexA- cells but decreased viability in recA- cultures; (ii) altered morphology of wild type and lexA, depending on the energy density, power, emission mode, and wavelength. Conclusion: Results show that low-level lasers have lethal effects on both recombination DNA repair and SOS response bacterial cells but do not induce morphological modifications in these cells.

scholarly journals Regulation of Copper Metabolism by Nitrogen Utilization in Saccharomyces cerevisiae

2021 ◽  
Vol 7 (9) ◽  
pp. 756
Author(s):  
Suzie Kang ◽  
Hyewon Seo ◽  
Min-Gyu Lee ◽  
Cheol-Won Yun
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Iron Uptake ◽  
Nitrogen Starvation ◽  
Copper Metabolism ◽  
Nitrogen Utilization ◽  
Deletion Mutants ◽  
Uptake System ◽  
Wild Type ◽  
High Affinity ◽  
Uptake Activity

To understand the relationship between carbon or nitrogen utilization and iron homeostasis, we performed an iron uptake assay with several deletion mutants with partial defects in carbon or nitrogen metabolism. Among them, some deletion mutants defective in carbon metabolism partially and the MEP2 deletion mutant showed lower iron uptake activity than the wild type. Mep2 is known as a high-affinity ammonia transporter in Saccharomyces cerevisiae. Interestingly, we found that nitrogen starvation resulted in lower iron uptake activity than that of wild-type cells without downregulation of the genes involved in the high-affinity iron uptake system FET3/FTR1. However, the gene expression of FRE1 and CTR1 was downregulated by nitrogen starvation. The protein level of Ctr1 was also decreased by nitrogen starvation, and addition of copper to the nitrogen starvation medium partially restored iron uptake activity. However, the expression of MAC1, which is a copper-responsive transcriptional activator, was not downregulated by nitrogen starvation at the transcriptional level but was highly downregulated at the translational level. Mac1 was downregulated dramatically under nitrogen starvation, and treatment with MG132, which is an inhibitor of proteasome-dependent protein degradation, partially attenuated the downregulation of Mac1. Taken together, these results suggest that nitrogen starvation downregulates the high-affinity iron uptake system by degrading Mac1 in a proteasome-dependent manner and eventually downregulates copper metabolism.

scholarly journals High-Resolution Genetic Mapping With Ordered Arrays of Saccharomyces cerevisiae Deletion Mutants

Genetics ◽  
2002 ◽  
Vol 162 (3) ◽  
pp. 1091-1099 ◽  
Author(s):  
Paul Jorgensen ◽  
Bryce Nelson ◽  
Mark D Robinson ◽  
Yiqun Chen ◽  
Brenda Andrews ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
High Resolution ◽  
Genetic Mapping ◽  
Large Scale ◽  
Model Organisms ◽  
Deletion Mutants ◽  
Wild Type ◽  
Allele Specific ◽  
Single Allele ◽  
Kinase Signaling Pathway

Abstract We present a method for high-resolution genetic mapping that takes advantage of the ordered set of viable gene deletion mutants, which form a set of colinear markers covering almost every centimorgan of the Saccharomyces cerevisiae genome, and of the synthetic genetic array (SGA) system, which automates the construction of double mutants formed by mating and meiotic recombination. The Cbk1 kinase signaling pathway, which consists minimally of CBK1, MOB2, KIC1, HYM1, and TAO3 (PAG1), controls polarized morphogenesis and activation of the Ace2 transcription factor. Deletion mutations in the Cbk1 pathway genes are tolerated differently by common laboratory strains of S. cerevisiae, being viable in the W303 background but dead in the S288C background. Genetic analysis indicated that the lethality of Cbk1 pathway deletions in the S288C background was suppressed by a single allele specific to the W303 background. SGA mapping (SGAM) was used to locate this W303-specific suppressor to the SSD1 locus, which contains a known polymorphism that appears to compromise SSD1 function. This procedure should map any mutation, dominant or recessive, whose phenotype is epistatic to wild type, that is, a phenotype that can be scored from a mixed population of cells obtained by germination of both mutant and wild-type spores. In principle, SGAM should be applicable to the analysis of multigenic traits. Large-scale construction of ordered mutations in other model organisms would broaden the application of this approach.

scholarly journals Intragenic complementation of amino and carboxy terminal SMN missense mutations can rescue Smn null mice

2020 ◽  
Author(s):  
Vicki L McGovern ◽  
Kaitlyn M Kray ◽  
W David Arnold ◽  
Sandra I Duque ◽  
Chitra C Iyer ◽  
...  
Keyword(s):  
Functional Unit ◽  
Muscular Atrophy ◽  
Missense Mutations ◽  
Wild Type ◽  
Sm Proteins ◽  
Intragenic Complementation ◽  
Missense Allele ◽  
Smn Protein ◽  
Neuron Electrophysiology ◽  
Carboxy Terminal

Abstract Spinal muscular atrophy is caused by reduced levels of SMN resulting from the loss of SMN1 and reliance on SMN2 for the production of SMN. Loss of SMN entirely is embryonic lethal in mammals. There are several SMN missense mutations found in humans. These alleles do not show partial function in the absence of wild-type SMN and cannot rescue a null Smn allele in mice. However, these human SMN missense allele transgenes can rescue a null Smn allele when SMN2 is present. We find that the N- and C-terminal regions constitute two independent domains of SMN that can be separated genetically and undergo intragenic complementation. These SMN protein heteromers restore snRNP assembly of Sm proteins onto snRNA and completely rescue both survival of Smn null mice and motor neuron electrophysiology demonstrating that the essential functional unit of SMN is the oligomer.

scholarly journals Saccharomyces cerevisiae RAD5-encoded DNA repair protein contains DNA helicase and zinc-binding sequence motifs and affects the stability of simple repetitive sequences in the genome.

1992 ◽  
Vol 12 (9) ◽  
pp. 3807-3818 ◽  
Author(s):  
R E Johnson ◽  
S T Henderson ◽  
T D Petes ◽  
S Prakash ◽  
M Bankmann ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Repair ◽  
Repetitive Sequences ◽  
Dna Helicase ◽  
Gene Arrangement ◽  
Sequence Motif ◽  
Sequence Motifs ◽  
Wild Type ◽  
Dna Repair Gene ◽  
Simple Repetitive Sequences

rad5 (rev2) mutants of Saccharomyces cerevisiae are sensitive to UV light and other DNA-damaging agents, and RAD5 is in the RAD6 epistasis group of DNA repair genes. To unambiguously define the function of RAD5, we have cloned the RAD5 gene, determined the effects of the rad5 deletion mutation on DNA repair, DNA damage-induced mutagenesis, and other cellular processes, and analyzed the sequence of RAD5-encoded protein. Our genetic studies indicate that RAD5 functions primarily with RAD18 in error-free postreplication repair. We also show that RAD5 affects the rate of instability of poly(GT) repeat sequences. Genomic poly(GT) sequences normally change length at a rate of about 10(-4); this rate is approximately 10-fold lower in the rad5 deletion mutant than in the corresponding isogenic wild-type strain. RAD5 encodes a protein of 1,169 amino acids of M(r) 134,000, and it contains several interesting sequence motifs. All seven conserved domains found associated with DNA helicases are present in RAD5. RAD5 also contains a cysteine-rich sequence motif that resembles the corresponding sequences found in 11 other proteins, including those encoded by the DNA repair gene RAD18 and the RAG1 gene required for immunoglobin gene arrangement. A leucine zipper motif preceded by a basic region is also present in RAD5. The cysteine-rich region may coordinate the binding of zinc; this region and the basic segment might constitute distinct DNA-binding domains in RAD5. Possible roles of RAD5 putative ATPase/DNA helicase activity in DNA repair and in the maintenance of wild-type rates of instability of simple repetitive sequences are discussed.

scholarly journals MAPPING AND GENE CONVERSION STUDIES WITH THE STRUCTURAL GENE FOR ISO-1-CYTOCHROME C IN YEAST

Genetics ◽  
1975 ◽  
Vol 81 (4) ◽  
pp. 615-629
Author(s):  
Christopher W Lawrence ◽  
Fred Sherman ◽  
Mary Jackson ◽  
Richard A Gilmore
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Gene Conversion ◽  
The Other ◽  
Crossing Over ◽  
Wild Type ◽  
Chromosome X ◽  
Tetrad Analysis ◽  
Yeast Saccharomyces Cerevisiae ◽  
Distal Marker ◽  
The Right

ABSTRACT We have investigated the order of the four genes cyc1, rad7, SUP4, and cdc8 which form a tightly linked cluster on the right arm of chromosome X in the yeast Saccharomyces cerevisiae. Crossing over and coconversion data from tetrad analysis established the gene order to be centromere–cyc1–rad7–SUP4. Also cdc8 appeared to be distal to SUP4 on the basis of crossovers that were associated with conversion of SUP4. The frequencies of recombination and the occurrence of coconversions suggest that these four genes are contiguous or at least nearly so. Gene-conversion frequencies for several cyc1 alleles were studied, including cyc1–1, a deletion of the whole gene that extends into the rad7 locus. The cyc1–1 deletion was found to be capable of conversion, though at a frequency some fivefold less than the other alleles studied, and both 3:1 and 1:3 events were detected. In general 1:3 and 3:1 conversion events were equally frequent at all loci studied, and approximately 50% of conversions were accompanied by reciprocal recombination for flanking markers. The orientation of the cyc1 gene could not be clearly deduced from the behavior of the distal marker SUP4 in wild-type recombinants that arose from diploids heteroallelic for cyc1 mutations.

scholarly journals GENETICS OF YEAST HEXOKINASE

Genetics ◽  
1977 ◽  
Vol 86 (4) ◽  
pp. 727-744
Author(s):  
Zita Lobo ◽  
P K Maitra
Keyword(s):  
Saccharomyces Cerevisiae ◽  
The Other ◽  
Missense Mutations ◽  
Structural Genes ◽  
Wild Type ◽  
Hexokinase Activity ◽  
Mutant Strains ◽  
Mutant Genes ◽  
Yeast Hexokinase ◽  
Respective Wild Type

ABSTRACT Two independent isolates of Saccharomyces cerevisiae lacking hexokinase activity (EC 2.7.1.1) are described. Both mutant strains grow on glucose but are unable to grow on fructose, and contain two mutant genes h×k1 and h×k2 each. The mutations are recessive and noncomplementing. Genetic analysis suggests that these two unlinked genes h×k1 and h×k2 determine, independently of each other, the synthesis of hexokinase isozymes P1 and P2, respectively. h×k1 is located on chromosome VIR distal to met10, and h×k2 is on chromosome IIIR distal to MAL2. Of four hexokinase-positive spontaneous reversions, one is very tightly linked to h×k1 and the other three to the h×k2 locus. The reverted enzymes are considerably more thermolabile than the respective wild-type enzymes, and in one case show altered immunological properties. Data are presented which suggest that the h×k1 and h×k2 mutations are missense mutations in the structural genes of hexokinase P1 and hexokinase P2, respectively. These are presumably the only enzymes that allow S. cerevisiae to grow on fructose.

scholarly journals Reduced Mismatch Repair of Heteroduplexes Reveals “Non”-interfering Crossing Over in Wild-Type Saccharomyces cerevisiae

Genetics ◽  
2008 ◽  
Vol 178 (3) ◽  
pp. 1251-1269 ◽  
Author(s):  
Tony J. Getz ◽  
Stephen A. Banse ◽  
Lisa S. Young ◽  
Allison V. Banse ◽  
Johanna Swanson ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mismatch Repair ◽  
Crossing Over ◽  
Wild Type

scholarly journals Saccharomyces cerevisiae Mer3 Is a DNA Helicase Involved in Meiotic Crossing Over

2002 ◽  
Vol 22 (10) ◽  
pp. 3281-3291 ◽  
Author(s):  
Takuro Nakagawa ◽  
Richard D. Kolodner
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Helicase ◽  
Double Strand Breaks ◽  
Crossing Over ◽  
Helicase Activity ◽  
Wild Type ◽  
Rna Helicases ◽  
Conserved Residues ◽  
Strand Breaks ◽  
Homologous Chromosomes

ABSTRACT Crossing over is regulated to occur at least once per each pair of homologous chromosomes during meiotic prophase to ensure proper segregation of chromosomes at the first meiotic division. In a mer3 deletion mutant of Saccharomyces cerevisiae, crossing over is decreased, and the distribution of the crossovers that occur is random. The predicted Mer3 protein contains seven motifs characteristic of the DExH box type of DNA/RNA helicases. The mer3G166D and the mer3K167A mutation, amino acid substitutions of conserved residues in a putative nucleotide-binding domain of the helicase motifs caused a defect in the transition of meiosis-specific double-strand breaks to later intermediates, decreased crossing over, and reduced crossover interference. The purified Mer3 protein was found to have DNA helicase activity. This helicase activity was reduced by the mer3GD mutation to <1% of the wild-type activity, even though binding of the mutant protein to single- and double-strand DNA was unaffected. The mer3KA mutation eliminated the ATPase activity of the wild-type protein. These results demonstrate that Mer3 is a DNA helicase that functions in meiotic crossing over.

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