scholarly journals Yeast mutants sensitive to antimicrotubule drugs define three genes that affect microtubule function.

Genetics ◽  
1990 ◽  
Vol 124 (2) ◽  
pp. 251-262 ◽  
Author(s):  
T Stearns ◽  
M A Hoyt ◽  
D Botstein
Keyword(s):  
Chromosome Loss ◽  
Gene Products ◽  
Wild Type ◽  
Tubulin Genes ◽  
New Genes ◽  
Complementation Groups ◽  
Yeast Mutants ◽  
Antimicrotubule Drugs ◽  
Tubulin Mutations ◽  
Microtubule Function

Abstract Three new genes affecting microtubule function in Saccharomyces cerevisiae were isolated by screening for mutants displaying supersensitivity to the antimicrotubule drug benomyl. Such mutants fall into six complementation groups: TUB1, TUB2 and TUB3, the three tubulin genes of yeast, and three new genes, which we have named CIN1, CIN2 and CIN4. Mutations in each of the CIN genes were also independently isolated by screening for mutants with increased rates of chromosome loss. Strains bearing mutations in the CIN genes are approximately tenfold more sensitive than wild type to both benomyl and to the related antimicrotubule drug, nocodazole. This phenotype is recessive for all alleles isolated. The CIN1, CIN2 and CIN4 genes were cloned by complementation of the benomyl-supersensitive phenotype. Null mutants of each of the genes are viable, and have phenotypes similar to those of the point mutants. Genetic evidence for the involvement of the CIN gene products in microtubule function comes from the observation that some tubulin mutations are suppressed by cin mutations, while other tubulin mutations are lethal in combination with cin mutations. Additional genetic experiments with cin mutants suggest that the three genes act together in the same pathway or structure to affect microtubule function.

scholarly journals Reduced Mad2 expression keeps relaxed kinetochores from arresting budding yeast in mitosis

2011 ◽  
Vol 22 (14) ◽  
pp. 2448-2457 ◽  
Author(s):  
Erin L. Barnhart ◽  
Russell K. Dorer ◽  
Andrew W. Murray ◽  
Scott C. Schuyler
Keyword(s):  
Chromosome Segregation ◽  
Budding Yeast ◽  
Spindle Checkpoint ◽  
Chromosome Loss ◽  
Wild Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Sister Chromatids ◽  
Chromatid Cohesion ◽  
Diploid Cells ◽  
Antimicrotubule Drugs

Chromosome segregation depends on the spindle checkpoint, which delays anaphase until all chromosomes have bound microtubules and have been placed under tension. The Mad1–Mad2 complex is an essential component of the checkpoint. We studied the consequences of removing one copy of MAD2 in diploid cells of the budding yeast, Saccharomyces cerevisiae. Compared to MAD2/MAD2 cells, MAD2/mad2Δ heterozygotes show increased chromosome loss and have different responses to two insults that activate the spindle checkpoint: MAD2/mad2Δ cells respond normally to antimicrotubule drugs but cannot respond to chromosomes that lack tension between sister chromatids. In MAD2/mad2Δ cells with normal sister chromatid cohesion, removing one copy of MAD1 restores the checkpoint and returns chromosome loss to wild-type levels. We conclude that cells need the normal Mad2:Mad1 ratio to respond to chromosomes that are not under tension.

scholarly journals MUTATIONS IN THE PHO80 GENE CONFER PERMEABILITY TO 5'-MONONUCLEOTIDES IN SACCHAROMYCES CEREVISIAE

Genetics ◽  
1982 ◽  
Vol 102 (3) ◽  
pp. 341-359
Author(s):  
Linda F Bisson ◽  
Jeremy Thorner
Keyword(s):  
Inorganic Phosphate ◽  
Phosphate Transport ◽  
Culture Conditions ◽  
Yeast Cells ◽  
Wild Type ◽  
Coordinate Control ◽  
Complementation Groups ◽  
The Right ◽  
Yeast Mutants ◽  
Type Strains

ABSTRACT Yeast mutants permeable to dTMP (tup) were selected and two new complementation groups (tup5 and tup7) were identified. Assay of the levels of both acid and alkaline phosphatase in cells grown under either repressing (5 mm PO4  -3) or derepressing (0.03 mm PO4  -3) conditions indicated that, in general, tup mutations cause cells to be defective in their regulation of phosphatase synthesis. In addition, three of the tup mutations (tup1, tup4 and tup7) displayed markedly elevated rates of inorganic phosphate transport. The tup7 locus was found to be tightly centromere-linked on the right arm of chromosome XV, and was shown to be allelic with the pho80 regulatory locus on the basis of both genetic and biochemical criteria. Analysis of other mutations known to affect phosphatase levels (pho) indicated that some also conferred permeability to dTMP. Possible allelic relationships between tup genes and certain of these pho mutations are discussed. Regardless of the culture conditions, wild-type strains were not permeable to dTMP; in contrast, it was found in the course of this work that normal yeast cells were permeable to dUMP and that dUMP permeability was regulated by the concentration of inorganic phosphate present in the medium used to grow the cells. Thus, permeability to 5′-mononucleotides appears to be under coordinate control with phosphatase synthesis.

scholarly journals Yeast Mutants Deficient in ER-Associated Degradation of the Z Variant of Alpha-1-Protease Inhibitor

Genetics ◽  
1996 ◽  
Vol 144 (4) ◽  
pp. 1355-1362 ◽  
Author(s):  
Ardythe A McCracken ◽  
Igor V Karpichev ◽  
James E Ernaga ◽  
Eric D Werner ◽  
Andrew G Dillin ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Degradation ◽  
Proteinase Inhibitor ◽  
Parent Strain ◽  
Mendelian Inheritance ◽  
Wild Type ◽  
Mutant Strains ◽  
Complementation Groups ◽  
Yeast Mutants ◽  
Wild Type Yeast

Saccharomyces cerevisiae mutants deficient in degradation of alpha-1-proteinase inhibitor Z (A1PiZ) have been isolated and genetically characterized. Wild-type yeast expressing A1PiZ synthesize an ER form of this protein that is rapidly degraded by an intracellular proteolytic process known as ER-associated protein degradation (ERAD). The mutant strains were identified after treatment with EMS using a colony blot immunoassay to detect colonies that accumulated high levels of A1PiZ. A total of 120,000 colonies were screened and 30 putative mutants were identified. The level of A1PiZ accumulation in these mutants, measured by ELISA, ranged from two to 11 times that of A1PiZ in the parent strain. Further studies demonstrated that the increased levels of A1PiZ in most of the mutant strains was not the result of defective secretion or elevated A1PiZ mRNA. Pulse chase experiments indicated that A1PiZ was stabilized in several strains, evidence that these mutants are defective in ER-associated protein degradation. Genetic analyses revealed that most of the mutations were recessive, ∼30% of the mutants characterized conformed to simple Mendelian inheritance, and at least seven complementation groups were identified.

scholarly journals Multiple new genes that determine activity for the first step of leucine biosynthesis in Saccharomyces cerevisiae.

Genetics ◽  
1988 ◽  
Vol 119 (1) ◽  
pp. 13-20 ◽  
Author(s):  
P Drain ◽  
P Schimmel
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Wild Type ◽  
Leucine Biosynthesis ◽  
Yeast Saccharomyces Cerevisiae ◽  
Multiple Components ◽  
New Genes ◽  
Yeast Strains ◽  
Complementation Groups ◽  
Or Genes ◽  
New Mutations

Abstract The first step in the biosynthesis of leucine is catalyzed by alpha-isopropylmalate (alpha-IPM) synthase. In the yeast Saccharomyces cerevisiae, LEU4 encodes the isozyme responsible for the majority of alpha-IPM synthase activity. Yeast strains that bear disruption alleles of LEU4, however, are Leu+ and exhibit a level of synthase activity that is 20% of the wild type. To identify the gene or genes that encode this remaining activity, a leu4 disruption strain was mutagenized. The mutations identified define three new complementation groups, designated leu6, leu7 and leu8. Each of these new mutations effect leucine auxotrophy only if a leu4 mutation is present and each results in loss of alpha-IPM synthase activity. Further analysis suggests that LEU7 and LEU8 are candidates for the gene or genes that encode an alpha-IPM synthase activity. The results demonstrate that multiple components determine the residual alpha-IPM synthase activity in leu4 gene disruption strains of S. cerevisiae.

scholarly journals Interacting genes that affect microtubule function in Drosophila melanogaster: two classes of mutation revert the failure to complement between haync2 and mutations in tubulin genes.

Genetics ◽  
1990 ◽  
Vol 125 (1) ◽  
pp. 77-90
Author(s):  
C L Regan ◽  
M T Fuller
Keyword(s):  
Drosophila Melanogaster ◽  
Gene Product ◽  
Genetic Interaction ◽  
Meiotic Spindle ◽  
Male Sterile ◽  
Alpha Tubulin ◽  
Tubulin Genes ◽  
Recessive Phenotype ◽  
Tubulin Mutations ◽  
Microtubule Function

Abstract The recessive male sterile mutation haync2 of Drosophila melanogaster fails to complement certain beta 2-tubulin and alpha-tubulin mutations, suggesting that the haywire product plays a role in microtubule function, perhaps as a structural component of microtubules. The genetic interaction appears to require the presence of the aberrant product encoded by haync2, which may act as a structural poison. Based on this observation, we have isolated ten new mutations that revert the failure to complement between haync2 and B2tn. The revertants tested behaved as intragenic mutations of hay in recombination tests, and fell into two phenotypic classes, suggesting two functional domains of the hay gene product. Some revertants were hemizygous viable and less severe than haync2 in their recessive phenotype. These mutations might revert the poison by restoring the aberrant product encoded by the haync2 allele to more wild-type function. Most of the revertants were recessive lethal mutations, indicating that the hay gene product is essential for viability. These more extreme mutations could revert the poison by destroying the ability of the aberrant haywirenc2 product to interact structurally with microtubules. Flies heterozygous for the original haync2 allele and an extreme revertant show defects in both the structure and the function of the male meiotic spindle.

scholarly journals A temperature-sensitive calmodulin mutant loses viability during mitosis.

1992 ◽  
Vol 118 (3) ◽  
pp. 607-617 ◽  
Author(s):  
T N Davis
Keyword(s):  
Wild Type Strain ◽  
Fold Increase ◽  
Chromosome Loss ◽  
Temperature Sensitive ◽  
Single Mutation ◽  
Nonpermissive Temperature ◽  
Wild Type ◽  
Nuclear Movement ◽  
Yeast Mutants ◽  
Calmodulin Mutant

Although rare, a recessive temperature-sensitive calmodulin mutant has been isolated in Saccharomyces cerevisiae. The mutant carries two mutations in CMD1, isoleucine 100 is changed to asparagine and glutamic acid 104 is changed to valine. Neither mutation alone conferred temperature sensitivity. A single mutation that allowed production of an intact but defective protein was not identified. At the nonpermissive temperature, the temperature-sensitive mutant displayed multiple defects. Bud formation and growth was delayed, but this defect was not responsible for the temperature-sensitive lethality. Cells synchronized in G1 progressed through the cell cycle and retained viability until the movement of the nucleus to the neck between the mother cell and the large bud. After nuclear movement, less than 5% of the cells survived the first mitosis and could form colonies when returned to permissive conditions. The duplicated DNA was dispersed along the spindle, extending from mother to daughter cell. Cells synchronized in G2/M lost viability immediately upon the shift to the nonpermissive temperature. At a semipermissive temperature, the mutant showed approximately a 10-fold increase in the rate of chromosome loss compared to a wild-type strain. The mitotic phenotype is very similar to yeast mutants that are defective in chromosome disjunction. The mutant also showed defects in cytokinesis.

scholarly journals New SNF genes, GAL11 and GRR1 affect SUC2 expression in Saccharomyces cerevisiae.

Genetics ◽  
1991 ◽  
Vol 129 (3) ◽  
pp. 675-684 ◽  
Author(s):  
L G Vallier ◽  
M Carlson
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Null Mutation ◽  
Wild Type ◽  
Glucose Limitation ◽  
Wild Type Level ◽  
Recessive Mutations ◽  
New Genes ◽  
Complementation Groups ◽  
Invertase Gene ◽  
Inducible Gene

Abstract To identify new genes required for depression of the SUC2 (invertase) gene in Saccharomyces cerevisiae, we have isolated mutants with defects in raffinose utilization. In addition to mutations in SUC2 and previously identified SNF genes, we recovered recessive mutations that define four new complementation groups, designated snf7 through snf10. These mutations cause defects in the derepression of SUC2 in response to glucose limitation. We also recovered five alleles of gal11 and showed that a gal11 null mutation decreases SUC2 expression to 30% of the wild-type level. Finally, one of the mutants carries a grr1 allele that converts SUC2 from a glucose-inducible gene.

Identification of a baculovirus polyhedron formation mutant with a novel phenotype

1996 ◽  
Vol 54 ◽  
pp. 796-797
Author(s):  
James M. Slavicek ◽  
Melissa J. Mercer ◽  
Mary Ellen Kelly
Keyword(s):  
Viral Gene ◽  
Gene Products ◽  
Type Number ◽  
Infection Cycle ◽  
Wild Type ◽  
Protein Matrix ◽  
Insect Midgut ◽  
Viral Particles ◽  
Budded Virus ◽  
Viral Form

Nucleopolyhedroviruses (NPV, family Baculoviridae) produce two morphological forms, a budded virus form and a viral form that is occluded into a paracrystalline protein matrix. This structure is termed a polyhedron and is composed primarily of the protein polyhedrin. Insects are infected by NPVs after ingestion of the polyhedron and release of the occluded virions through dissolution of the polyhedron in the alkaline environment of the insect midgut. Early after infection the budded virus form is produced. It buds through the plasma membrane and then infects other cells. Later in the infection cycle the occluded form of the virus is generated (reviewed by Blissard and Rohrmann, 1990).The processes of polyhedron formation and virion occlusion are likely to involve a number of viral gene products. However, only two genes, the polyhedrin gene and 25K FP gene, have been identified to date that are necessary for the wild type number of polyhedra to be formed and viral particles occluded.

scholarly journals CSE4 Genetically Interacts With the Saccharomyces cerevisiae Centromere DNA Elements CDE I and CDE II but Not CDE III: Implications for the Path of the Centromere DNA Around a Cse4p Variant Nucleosome

Genetics ◽  
2000 ◽  
Vol 156 (3) ◽  
pp. 973-981
Author(s):  
Kevin C Keith ◽  
Molly Fitzgerald-Hayes
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chromosome Loss ◽  
Structural Studies ◽  
Wild Type ◽  
Histone Fold ◽  
Histone Fold Domain ◽  
Histone H3 Variant ◽  
Dna Elements ◽  
Mutant Cells ◽  
Loss Rates

Abstract Each Saccharomyces cerevisiae chromosome contains a single centromere composed of three conserved DNA elements, CDE I, II, and III. The histone H3 variant, Cse4p, is an essential component of the S. cerevisiae centromere and is thought to replace H3 in specialized nucleosomes at the yeast centromere. To investigate the genetic interactions between Cse4p and centromere DNA, we measured the chromosome loss rates exhibited by cse4 cen3 double-mutant cells that express mutant Cse4 proteins and carry chromosomes containing mutant centromere DNA (cen3). When compared to loss rates for cells carrying the same cen3 DNA mutants but expressing wild-type Cse4p, we found that mutations throughout the Cse4p histone-fold domain caused surprisingly large increases in the loss of chromosomes carrying CDE I or CDE II mutant centromeres, but had no effect on chromosomes with CDE III mutant centromeres. Our genetic evidence is consistent with direct interactions between Cse4p and the CDE I-CDE II region of the centromere DNA. On the basis of these and other results from genetic, biochemical, and structural studies, we propose a model that best describes the path of the centromere DNA around a specialized Cse4p-nucleosome.

Isolation of a Schizosaccharomyces pombe rad21ts Mutant That Is Aberrant in Chromosome Segregation, Microtubule Function, DNA Repair and Sensitive to Hydroxyurea: Possible Involvement of Rad21 in Ubiquitin-Mediated Proteolysis

Genetics ◽  
1998 ◽  
Vol 148 (1) ◽  
pp. 49-57
Author(s):  
Kazuo Tatebayashi ◽  
Jun-ichi Kato ◽  
Hideo Ikeda
Keyword(s):  
Dna Repair ◽  
Temperature Sensitive ◽  
Permissive Temperature ◽  
Repair Gene ◽  
Tubulin Genes ◽  
Gene Coding ◽  
Abnormal Mitosis ◽  
Dna Repair Gene ◽  
Nuclear Structures ◽  
Microtubule Function

Abstract The fission yeast DNA repair gene rad21+ is essential for cell growth. To investigate the function essential for cell proliferation, we have isolated a temperature-sensitive mutant of the rad21+ gene. The mutant, rad21-K1, showed abnormal mitosis at the nonpermissive temperature. Some cells contained abnormal nuclear structures, such as condensed chromosomes with short spindles, or chromosomes stretched or unequally separated by elongating spindles. Other cells exhibited the displaced nucleus or a cut-like phenotype. Similar abnormalities were observed when the Rad21 protein was depleted from cells. We therefore concluded that Rad21 is essential for proper segregation of chromosomes. Moreover, the rad21-K1 mutant is sensitive not only to UV and γ-ray irradiation but to thiabendazole and hydroxyurea, indicating that Rad21 plays important roles in microtubule function, DNA repair, and S phase function. The relation to the microtubule function was further confirmed by the fact that rad21+ genetically interacts with tubulin genes, nda2+ and nda3+. Finally, the growth of the rad21-K1 mutant was inhibited at the permissive temperature by introduction of another mutation in the cut9+ gene, coding for a component of the 20S cyclosome/anaphase promoting complex, which is involved in ubiquitin-mediated proteolysis. The results suggest that these diverse functions of Rad21 may be facilitated through ubiquitin-mediated proteolysis.

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