scholarly journals DELETION OF MITOCHONDRIAL DNA BYPASSING A CHROMOSOMAL GENE NEEDED FOR MAINTENANCE OF THE KILLER PLASMID OF YEAST

Genetics ◽  
1977 ◽  
Vol 87 (3) ◽  
pp. 441-452
Author(s):  
Reed B Wickner
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mitochondrial Dna ◽  
Mitochondrial Genome ◽  
Antimycin A ◽  
Chromosomal Gene ◽  
Wild Type ◽  
Suppressor Mutations ◽  
Induced Mutants ◽  
Chromosomal Genes ◽  
Killer Plasmid

ABSTRACT Strains of Saccharomyces cerevisiae carrying a 1.4 × 106 dalton double-stranded (ds) RNA in virus-like particles (the killer plasmid or virus) secrete a toxin that is lethal to strains not carrying this plasmid (virus). The mak10 gene is one of 24 chromosomal genes (called pets, mak1, mak2,…) that are needed to maintain and replicate the killer plasmid. We report here isolation of spontaneous and induced mutants in which the killer plasmid is maintained and replicated in spite of a defect in the mak10 gene. The bypass (or suppressor) mutations in these strains are in the mitochondrial genome. Respiratory deficiency produced by various chromosomal pet mutations, by chloramphenicol, or by antimycin A, does not bypass the mak10-1 mutation. Several spontaneous mak10-1 killer strains have about 12-fold more of the killer plasmid ds RNA than do wild-type killers. Although the absence of mitochondrial DNA bypasses mak10-1, it does not bypass pets-1, mak1-1, mak3-1, mak4-1, mak5-1, mak6-1, mak7-1, or mak8-1.

scholarly journals MUTANTS OF THE KILLER PLASMID OF SACCHAROMYCES CEREVISIAE DEPENDENT ON CHROMOSOMAL DIPLOIDY FOR EXPRESSION AND MAINTENANCE

Genetics ◽  
1976 ◽  
Vol 82 (2) ◽  
pp. 273-285
Author(s):  
Reed B Wickner
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Elevated Temperature ◽  
Mating Type ◽  
Chromosomal Gene ◽  
Wild Type ◽  
Opposite Mating Type ◽  
Diploid Clone ◽  
Wild Type Phenotype ◽  
Chromosomal Genes ◽  
Killer Plasmid

ABSTRACT Mutants of the killer plasmid of Saccharomyecs cerevisiaehave been isolated that depend upon chromosomal diploidy for the expression of plasmid functions and for replication or maintenance of the plasmid itself. These mutants are not defective in any chromosomal gene needed for expression or replication of the killer plasmid.—Haploids carrying these mutant plasmids (called d for diploid-dependent) are either unable to kill or unable to resist being killed or both and show frequent loss of the plasmid. The wild-type phenotype (K+R+) is restored by mating the d plasmid-carrying strain with either (a) a wild-type sensitive strain which apparently has no killer plasmid; (b) a strain which has been cured of the killer plasmid by growth at elevated temperature; (c) a strain which has been cured of the plasmid by growth in the presence of cycloheximide; (d) a strain which has lost the plasmid because it carries a mutation in a chromosomal mak gene; or (e) a strain of the opposite mating type which carries the same d plasmid and has the same defective phenotype, indicating that the restoration of the normal phenotype is not due to recombination between plasmid genomes or complementation of plasmid or chromosomal genes.—Sporulation of the phenotypically K+R+ diploids formed in matings between d and wild-type nonkiller strains yields tetrads, all four of whose haploid spores are defective for killing or resistance or maintenance of the plasmid or a combination of these. Every defective phenotype may be found among the segregants of a single diploid clone carrying a d plasmid. These defective segregants resume the normal killer phenotype in the diploids formed when a second round of mating is performed, and the segregants from a second round of meiosis and sporulation are again defective.

scholarly journals TWO CHROMOSOMAL GENES REQUIRED FOR KILLING EXPRESSION IN KILLER STRAINS OF SACCHAROMYCES CEREVISIAE

Genetics ◽  
1976 ◽  
Vol 82 (3) ◽  
pp. 429-442
Author(s):  
Reed B Wickner ◽  
Michael J Leibowitz
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Molecular Weight ◽  
Mutant Phenotype ◽  
Wild Type ◽  
Double Stranded Rna ◽  
Killer Strain ◽  
Chromosomal Genes ◽  
Complementation Groups ◽  
Killer Plasmid ◽  
Type Strains

ABSTRACT The killer character of yeast is determined by a 1.4 × 106 molecular weight double-stranded RNA plasmid and at least 12 chromosomal genes. Wild-type strains of yeast that carry this plasmid (killers) secrete a toxin which is lethal only to strains not carrying this plasmid (sensitives). —— We have isolated 28 independent recessive chromosomal mutants of a killer strain that have lost the ability to secrete an active toxin but remain resistant to the effects of the toxin and continue to carry the complete cytoplasmic killer genome. These mutants define two complementation groups, kex1 and kex2. Kex1 is located on chromosome VII between ade5 and lys5. Kex2 is located on chromosome XIV, but it does not show meiotic linkage to any gene previously located on this chromosome. —— When the killer plasmid of kex1 or kex2 strains is eliminated by curing with heat or cycloheximide, the strains become sensitive to killing. The mutant phenotype reappears among the meiotic segregants in a cross with a normal killer. Thus, the kex phenotype does not require an alteration of the killer plasmid. —— Kex1 and kex2 strains each contain near-normal levels of the 1.4 × 106 molecular weight double-stranded RNA, whose presence is correlated with the presence of the killer genome.

Conversion at large intergenic regions of mitochondrial DNA in Saccharomyces cerevisiae

1990 ◽  
Vol 10 (4) ◽  
pp. 1530-1537
Author(s):  
P J Skelly ◽  
G D Clark-Walker
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mitochondrial Dna ◽  
Rrna Gene ◽  
Supporting Evidence ◽  
Unexpected Result ◽  
Wild Type ◽  
Mitochondrial Dna Deletion ◽  
Direct Role ◽  
Atpase Subunit ◽  
Intergenic Regions

Saccharomyces cerevisiae mitochondrial DNA deletion mutants have been used to examine whether base-biased intergenic regions of the genome influence mitochondrial biogenesis. One strain (delta 5.0) lacks a 5-kilobase (kb) segment extending from the proline tRNA gene to the small rRNA gene that includes ori1, while a second strain (delta 3.7) is missing a 3.7-kb region between the genes for ATPase subunit 6 and glutamic acid tRNA that encompasses ori7 plus ori2. Growth of these strains on both fermentable and nonfermentable substrates does not differ from growth of the wild-type strain, indicating that the deletable regions of the genome do not play a direct role in the expression of mitochondrial genes. Examination of whether the 5- or 3.7-kb regions influence mitochondrial DNA transmission was undertaken by crossing strains and examining mitochondrial genotypes in zygotic colonies. In a cross between strain delta 5.0, harboring three active ori elements (ori2, ori3, and ori5), and strain delta 3.7, containing only two active ori elements (ori3 and ori5), there is a preferential recovery of the genome containing two active ori elements (37% of progeny) over that containing three active elements (20%). This unexpected result, suggesting that active ori elements do not influence transmission of respiratory-competent genomes, is interpreted to reflect a preferential conversion of the delta 5.0 genome to the wild type (41% of progeny). Supporting evidence for conversion over biased transmission is shown by preferential recovery of a nonparental genome in the progeny of a heterozygous cross in which both parental molecules can be identified by size polymorphisms.

scholarly journals Conversion at large intergenic regions of mitochondrial DNA in Saccharomyces cerevisiae.

1990 ◽  
Vol 10 (4) ◽  
pp. 1530-1537 ◽  
Author(s):  
P J Skelly ◽  
G D Clark-Walker
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mitochondrial Dna ◽  
Rrna Gene ◽  
Supporting Evidence ◽  
Unexpected Result ◽  
Wild Type ◽  
Mitochondrial Dna Deletion ◽  
Direct Role ◽  
Atpase Subunit ◽  
Intergenic Regions

Saccharomyces cerevisiae mitochondrial DNA deletion mutants have been used to examine whether base-biased intergenic regions of the genome influence mitochondrial biogenesis. One strain (delta 5.0) lacks a 5-kilobase (kb) segment extending from the proline tRNA gene to the small rRNA gene that includes ori1, while a second strain (delta 3.7) is missing a 3.7-kb region between the genes for ATPase subunit 6 and glutamic acid tRNA that encompasses ori7 plus ori2. Growth of these strains on both fermentable and nonfermentable substrates does not differ from growth of the wild-type strain, indicating that the deletable regions of the genome do not play a direct role in the expression of mitochondrial genes. Examination of whether the 5- or 3.7-kb regions influence mitochondrial DNA transmission was undertaken by crossing strains and examining mitochondrial genotypes in zygotic colonies. In a cross between strain delta 5.0, harboring three active ori elements (ori2, ori3, and ori5), and strain delta 3.7, containing only two active ori elements (ori3 and ori5), there is a preferential recovery of the genome containing two active ori elements (37% of progeny) over that containing three active elements (20%). This unexpected result, suggesting that active ori elements do not influence transmission of respiratory-competent genomes, is interpreted to reflect a preferential conversion of the delta 5.0 genome to the wild type (41% of progeny). Supporting evidence for conversion over biased transmission is shown by preferential recovery of a nonparental genome in the progeny of a heterozygous cross in which both parental molecules can be identified by size polymorphisms.

scholarly journals Oxygen and haem regulate the synthesis of peroxisomal proteins: catalase A, acyl-CoA oxidase and Pex1p in the yeast Saccharomyces cerevisiae; the regulation of these proteins by oxygen is not mediated by haem

2000 ◽  
Vol 350 (1) ◽  
pp. 313-319 ◽  
Author(s):  
Marek SKONECZNY ◽  
Joanna RYTKA
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mitochondrial Genome ◽  
Oxygen Sensor ◽  
Transcriptional Factor ◽  
The Other ◽  
Wild Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Regulatory Factors ◽  
Genes Encoding ◽  
Acyl Coa Oxidase

Saccharomyces cerevisiae genes related to respiration are typically controlled by oxygen and haem. Usually the regulation by these factors is co-ordinated; haem is indicated as the oxygen sensor. However, the responsiveness of peroxisome functions to these regulatory factors is poorly understood. The expression of CTA1, POX1 and PEX1 genes encoding the peroxisomal proteins catalase A, acyl-CoA oxidase and Pex1p peroxin respectively was studied under various conditions: in anaerobiosis, in the absence of haem and in respiratory incompetence caused by the lack of a mitochondrial genome (ρ0). The influence of haem deficiency or ρ0 on peroxisomal morphology was also investigated. Respiratory incompetence has no effect on the expression of CTA1 and POX1, whereas in the absence of haem their expression is markedly decreased. The synthesis of Pex1p is decreased in ρ0 cells and is decreased even more in haem-deficient cells. Nevertheless, peroxisomal morphology in both these types of cell does not differ significantly from the morphology of peroxisomes in wild-type cells. The down-regulating effect of anoxia on the expression of CTA1 and POX1 is even stronger than the effect of haem deficiency and is not reversed by the addition of exogenous haem or the presence of endogenous haem. Moreover, neither of these genes responds to the known haem-controlled transcriptional factor Hap1p. In contrast with the other two genes studied, PEX1 is up-regulated in anaerobiosis. The existence of one or more novel mechanisms of regulation of peroxisomal genes by haem and oxygen, different from those already known in S. cerevisiae, is postulated.

scholarly journals The cold sensitivity of a mutant of Saccharomyces cerevisiae lacking a mitochondrial heat shock protein 70 is suppressed by loss of mitochondrial DNA.

1996 ◽  
Vol 134 (3) ◽  
pp. 603-613 ◽  
Author(s):  
B Schilke ◽  
J Forster ◽  
J Davis ◽  
P James ◽  
W Walter ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mitochondrial Dna ◽  
Heat Shock ◽  
Heat Shock Protein ◽  
Cold Sensitivity ◽  
Growth Defect ◽  
Wild Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
The Matrix ◽  
Cold Sensitive

SSH1, a newly identified member of the heat shock protein (hsp70) multigene family of the budding yeast Saccharomyces cerevisiae, encodes a protein localized to the mitochondrial matrix. Deletion of the SSH1 gene results in extremely slow growth at 23 degrees C or 30 degrees C, but nearly wild-type growth at 37 degrees C. The matrix of the mitochondria contains another hsp70, Ssc1, which is essential for growth and required for translocation of proteins into mitochondria. Unlike SSC1 mutants, an SSH1 mutant showed no detectable defects in import of several proteins from the cytosol to the matrix compared to wild type. Increased expression of Ssc1 partially suppressed the cold-sensitive growth defect of the SSH1 mutant, suggesting that when present in increased amounts, Ssc1 can at least partially carry out the normal functions of Ssh1. Spontaneous suppressors of the cold-sensitive phenotype of an SSH1 null mutant were obtained at a high frequency at 23 degrees C, and were all found to be respiration deficient. 15 of 16 suppressors that were analyzed lacked mitochondrial DNA, while the 16th had reduced amounts. We suggest that Ssh1 is required for normal mitochondrial DNA replication, and that disruption of this process in ssh1 cells results in a defect in mitochondrial function at low temperatures.

scholarly journals [HOK], A NEW YEAST NON-MENDELIAN TRAIT, ENABLES A REPLICATION-DEFECTIVE KILLER PLASMID TO BE MAINTAINED

Genetics ◽  
1982 ◽  
Vol 100 (2) ◽  
pp. 159-174
Author(s):  
Reed B Wickner ◽  
Akio Toh-E
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Copy Number ◽  
Double Stranded Rna ◽  
Protein Toxin ◽  
Defective Mutant ◽  
Chromosomal Genes ◽  
Killer Plasmid ◽  
New Yeast ◽  
Lower Copy ◽  
Host Strains

ABSTRACT The K1 killer plasmid, [KIL-k1], of Saccharomyces cerevisiae is a 1.25 × 106 dalton linear double-stranded RNA plasmid coding for a protein toxin and immunity to that toxin. The [KIL-sd1] plasmid is a replication-defective mutant of [KIL-k1] that depends on one of the recessive chromosomal superkiller (ski  -) mutations for its maintenance (Toh-e and Wickner 1979). This report concerns a means by which [KIL-sd1] can be stably maintained in a SKI  + host. Strains carrying a plasmid we call [HOK] (helper of killer) stably maintain [KIL-sd1]. [HOK] segregates 4 [HOK]:0 in meiotic crosses and is efficiently transferred by cytoplasmic mixing (heterokaryon formation). [HOK] depends for its maintenance on the products of PET18, MAK3, and MAK10, three chromosomal genes needed to maintain [KIL-k1], but is independent of 10 other MAK genes and of MKT1. [HOK] is not mitochondrial DNA and is unaffected by agents which convert ψ+ strains to ψ-. [HOK] is also distinct from the previously described plasmids [URE3], 20S RNA, 2 µ DNA, and [EXL]. Strains lacking [HOK] consistently have a four-fold lower copy number of L double-stranded RNA than strains carrying [HOK].

scholarly journals RECESSIVE LETHAL AMBER SUPPRESSORS IN YEAST

Genetics ◽  
1975 ◽  
Vol 79 (4) ◽  
pp. 551-560
Author(s):  
Marjorie C Brandriss ◽  
Larry Soll ◽  
David Botstein
Keyword(s):  
Saccharomyces Cerevisiae ◽  
The Other ◽  
Wild Type ◽  
Diploid Strain ◽  
Recessive Lethal ◽  
Suppressor Mutations ◽  
Amber Suppressor ◽  
Chromosome Iii

ABSTRACT Recessive lethal amber suppressor mutations have been isolated in a diploid strain of Saccharomyces cerevisiae. Diploids carrying these suppressors upon sporulation yield asci with only two live spores, both lacking the suppressor. At least two classes of recessive lethal suppressors exist. Aneuploid strains carrying one wild type and one suppressor locus have been isolated and used in mapping studies; one suppressor maps on chromosome III, the other does not.

scholarly journals Role of glutathione in heat-shock-induced cell death of Saccharomyces cerevisiae

2000 ◽  
Vol 352 (1) ◽  
pp. 71-78 ◽  
Author(s):  
Kei-ichi SUGIYAMA ◽  
Atsuki KAWAMURA ◽  
Shingo IZAWA ◽  
Yoshiharu INOUE
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mitochondrial Dna ◽  
Heat Shock ◽  
Type Strain ◽  
Wild Type Strain ◽  
Wild Type ◽  
Glutathione Synthesis ◽  
Heat Shock Stress ◽  
Shock Stress

Previously we reported that expression of GSH1 (γ-glutamylcysteine synthetase) and GSH2 (glutathione synthetase) of the yeast Saccharomyces cerevisiae was increased by heat-shock stress in a Yap1p-dependent fashion and consequently intracellular glutathione content was increased [Sugiyama, Izawa and Inoue (2000) J. Biol. Chem. 275, 15535–15540]. In the present study, we discuss the physiological role of glutathione in the heat-shock stress response in this yeast. Both gsh1 and gsh2 mutants could acquire thermotolerance by mild heat-shock stress and induction of Hsp104p in both mutants was normal; however, mutant cells died faster by heat shock than their parental wild-type strain. After pretreatment at a sublethal temperature, the number of respiration-deficient mutants increased in a gsh1 mutant strain in the early stages of exposure to a lethal temperature, although this increase was partially suppressed by the addition of glutathione. These results lead us to suspect that an increase of glutathione synthesis during heat-shock stress is to protect mitochondrial DNA from oxidative damage. To investigate the correlation between mitochondrial DNA damage and glutathione, mitochondrial Mn-superoxide dismutase (the SOD2 gene product) was disrupted. As a result, the rate of generation of respiration-deficient mutants of a sod2∆ strain was higher than that of the isogenic wild-type strain and treatment of the sod2∆ mutant with buthionine sulphoximine, an inhibitor of glutathione synthesis, inhibited cell growth. These results suggest that glutathione synthesis is induced by heat shock to protect the mitochondrial DNA from oxidative damage that may lead to cell death.

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