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.

scholarly journals A MUTANT KILLER PLASMID WHOSE REPLICATION DEPENDS ON A CHROMOSOMAL "SUPERKILLER" MUTATION

Genetics ◽  
1979 ◽  
Vol 91 (4) ◽  
pp. 673-682
Author(s):  
Akio Toh-E ◽  
Reed B Wickner
Keyword(s):  
Molecular Weight ◽  
Specific Form ◽  
Wild Type ◽  
Double Stranded Rna ◽  
Virus Like Particles ◽  
Chromosomal Mutation ◽  
Recessive Mutations ◽  
Yeast Strains ◽  
Chromosomal Genes ◽  
Killer Plasmid

ABSTRACT Yeast strains carrying a 1.5 × 106 molecular weight linear double-stranded RNA in virus-like particles (M dsRKA, the killer plasmid or virus) secrete a toxin that is lethal to strains not carrying this plasmid. Recessive mutations in any of four chromosomal genes (called skil-ski4) result in increased production of toxin activity. We report here a mutation of the killer plasmid (called [KIL-sd] for ski-dependent) that makes the killer plasmid dependent for its replication on the presence of a chromosomal mutation in any ski gene. Thus, the [KIL-sd] plasmid is lost from SKI+ strains. When the wild-type killer plasmid, [KIL-k], is introduced into a ski2-2 [KIL-o] strain, the killer plasmid changes to a [KIL-sd] plasmid. This may represent a specific form of mutagenesis or selective replication in the ski2-2 strain of [KIL-sd] variants (mutants) in the normal [KIL-k] population. The ski2-1 and ski2-3 mutations do not convert [KIL-k] to [KIL-sd], but ski2-3 does allow maintenance of the [KIL-sd] plasmid. The [KIL-sd] plasmid thus lacks a plasmid site or product needed for replication in wild-type cells.

scholarly journals TWENTY-SIX CHROMOSOMAL GENES NEEDED TO MAINTAIN THE KILLER DOUBLE-STRANDED RNA PLASMID OF SACCHAROMYCES CEREVISIAE

Genetics ◽  
1978 ◽  
Vol 88 (3) ◽  
pp. 419-425
Author(s):  
Reed B Wickner
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Gene Product ◽  
Double Stranded Rna ◽  
Plasmid Maintenance ◽  
Protein Toxin ◽  
Yeast Strains ◽  
Chromosomal Genes ◽  
Complementation Groups ◽  
Killer Plasmid

ABSTRACT The double-stranded RNA killer plasmid gives yeast strains carrying it both the ability to secrete a protein toxin and immunity to that toxin. This report describes a new series of mutants in chromsomal genes needed for killer plasmid maintenance (mak genes). These mutants comprise 12 complementation groups. There are a total of at least 26 mak genes. Each mak gene product is needed for plasmid maintenance in diploids as well as in haploids. None of these mak mutations prevent the killer plasmid from entering the mak  - spores in the process of meiotic sporulation. Complementation between mak mutants can be performed by mating meiotic spores from a makx/α plasmid-carrying diploid with a maky haploid. If x = y, about half the diploid clones formed lose the killer plasmid. If x # y, complementation occurs, and all of the diploid clones are killers.

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 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 DOMINANT CHROMOSOMAL MUTATION BYPASSING CHROMOSOMAL GENES NEEDED FOR KILLER RNA PLASMID REPLICATION IN YEAST

Genetics ◽  
1977 ◽  
Vol 87 (3) ◽  
pp. 453-469
Author(s):  
Reed B Wickner ◽  
Michael J Leibowitz
Keyword(s):  
Plasmid Replication ◽  
Wild Type ◽  
Double Stranded Rna ◽  
Virus Like Particles ◽  
Chromosomal Mutation ◽  
Reversion Frequency ◽  
Yeast Strains ◽  
Chromosomal Genes ◽  
Chromosomal Changes ◽  
Killer Plasmid

ABSTRACT Yeast strains carrying a double-stranded RNA plasmid of 1.4-1.7 × 106 daltons encapsulated in virus-like particles secrete a toxin that kills strains lacking this plasmid. The plasmid requires at least 24 chromosomal genes (pets, and mak1 through mak23) for its replication or maintenance. We have detected dominant Mendelian mutations (called KRB1 for killer replication bypass) that bypass two chromosomal genes, mak7 and pets, normally needed for plasmid replication. Strains mutant in mak7 and carrying the bypass mutation (mak7-1 KRB1) are isolated as frequent K+R+ sectors of predominantly K-R- segregants from crosses of mak7-1 with a wild-type killer. All KRB1 mutations isolated in this way are inherited as single dominant centromere-linked chromosomal changes. They define a new centromere. KRB1 is not a translational suppressor. KRB1 strains contain a genetically normal killer plasmid and ds RNA species approximately the same in size and amount as do wild-type killers. Bypass of both mak7 and pets by one mutation suggests that these two genes are functionally related. Two properties of the inheritance of KRB1 indicate an unusually high reversion frequency: (1) Heat or cycloheximide (treatments known to cure strains of the wild-type killer plasmid) readily induce conversion of mak7-1 KRB1 strains from killers to nonkillers with concomitant disappearance of KRB1 as judged by further crosses, and (2) mating two strains of the type mak7-1 KRB1 with each other yields mostly 2 K+R+: 2 K-R- segregation, although the same KRB1 mutation and the same killer plasmid are present in both parents.

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 Influences of Histone Stoichiometry on the Target Site Preference of Retrotransposons Ty1 and Ty2 in Saccharomyces cerevisiae

Genetics ◽  
1996 ◽  
Vol 142 (3) ◽  
pp. 761-776 ◽  
Author(s):  
Lori A Rinckel ◽  
David J Garfinkel
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Promoter Region ◽  
Target Site ◽  
Site Preference ◽  
Wild Type ◽  
Histone Proteins ◽  
Protein Levels ◽  
In The Wild ◽  
Type Strains ◽  
Orientation Bias

Abstract In Saccharomyces cerevisiae, the target site specificity of the retrotransposon Ty1 appears to involve the Ty integration complex recognizing chromatin structures. To determine whether changes in chromatin structure affect Ty1 and Ty2 target site preference, we analyzed Ty transposition at the CAN1 locus in mutants containing altered levels of histone proteins. A Δhta1-htb1 mutant with decreased levels of H2A and H2B histone proteins showed a pattern of Ty1 and Ty2 insertions at CAN1 that was significantly different from that of both the wild-type and a Δhta2-htb2 mutant, which does not have altered histone protein levels. Altered levels of H2A and H2B proteins disrupted a dramatic orientation bias in the CAN1 promoter region. In the wild-type strains, few Ty1 and Ty2 insertions in the promoter region were oriented opposite to the direction of CAN1 transcription. In the Δhta1-htb1 background, however, numerous Ty1 and Ty2 insertions were in the opposite orientation clustered within the TATA region. This altered insertion pattern does not appear to be due to a bias caused by selecting canavanine resistant isolates in the different HTA1-HTB1 backgrounds. Our results suggest that reduced levels of histone proteins alter Ty target site preference and disrupt an asymmetric Ty insertion pattern.

scholarly journals Mutants inSaccharomyces lactiscontrolling both β-glucosidase and β-galactosidase activities

1972 ◽  
Vol 19 (1) ◽  
pp. 27-32 ◽  
Author(s):  
M. Tingle ◽  
H. O. Halvorson
Keyword(s):  
Nuclear Gene ◽  
Mutant Phenotype ◽  
Single Mutation ◽  
Wild Type ◽  
Genetic Studies ◽  
Glucosidase Activity ◽  
Type Strains

SUMMARYInSaccharomyces lactis, a class of mutants isolated for low β-glucosidase activity are reduced in activity for β-galactosidase as well. Genetic studies indicate that their properties are the result of a single mutation in a nuclear gene. In diploide containing a wild-type and mutant β-galactosidase allele, the mutant phenotype is partially dominant. The two enzymes can be separated physically and under appropriate conditions are induced independently in wild-type strains.

Multiple GCD genes required for repression of GCN4, a transcriptional activator of amino acid biosynthetic genes in Saccharomyces cerevisiae

1986 ◽  
Vol 6 (11) ◽  
pp. 3990-3998
Author(s):  
S Harashima ◽  
A G Hinnebusch
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acid ◽  
Lacz Gene ◽  
Gene Products ◽  
Wild Type ◽  
Double Mutation ◽  
Double Stranded Rna ◽  
Amino Acid Availability ◽  
Genes Encoding ◽  
New Alleles

GCN4 encodes a positive regulator of multiple unlinked genes encoding amino acid biosynthetic enzymes in Saccharomyces cerevisiae. Expression of GCN4 is coupled to amino acid availability by a control mechanism involving GCD1 as a negative effector and GCN1, GCN2, and GCN3 as positive effectors of GCN4 expression. We used reversion of a gcn2 gcn3 double mutation to isolate new alleles of GCD1 and mutations in four additional GCD genes which we designate GCD10, GCD11, GCD12, and GCD13. All of the mutations lead to constitutive derepression of HIS4 transcription in the absence of the GCN2+ and GCN3+ alleles. By contrast, the gcd mutations require the wild-type GCN4 allele for their derepressing effect, suggesting that each acts by influencing the level of GCN4 activity in the cell. Consistent with this interpretation, mutations in each GCD gene lead to constitutive derepression of a GCN4::lacZ gene fusion. Thus, at least five gene products are required to maintain the normal repressed level of GCN4 expression in nonstarvation conditions. Interestingly, the gcd mutations are pleiotropic and also affect growth rate in nonstarvation conditions. In addition, certain alleles lead to a loss of M double-stranded RNA required for the killer phenotype. This pleiotropy suggests that the GCD gene products contribute to an essential cellular function, in addition to, or in conjunction with, their role in GCN4 regulation.

Bioreduction of Some Common Carbonylic Compounds Mediated by Yeasts

2010 ◽  
Vol 65 (1-2) ◽  
pp. 1-9 ◽  
Author(s):  
Javier Silva ◽  
Julio Alarcón ◽  
Sergio A. Aguila ◽  
Joel B. Alderete
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Pichia Pastoris ◽  
Aqueous Medium ◽  
Ethyl Acetoacetate ◽  
Enantiomeric Excess ◽  
Optically Active ◽  
Environmentally Benign ◽  
Wild Type ◽  
Regeneration System ◽  
Type Strains

Bioreduction of several prochiral carbonylic compounds such as acetophenone (1), ethyl acetoacetate (2) and ethyl phenylpropionate (3) to the corresponding optically active secalcohols 1a - 3a was performed using wild-type strains of Pichia pastoris UBB 1500, Rhodotorula sp., and Saccharomyces cerevisiae. The reductions showed moderate to excellent conversion and high enantiomeric excess, in an extremely mild and environmentally benign manner in aqueous medium, using glucose as cofactor regeneration system. The obtained alcohols follow Prelog’s rule, but in the reduction of 1 with P. pastoris UBB 1500 the anti- Prelog enantiopreference was observed

Sign in / Sign up

Export Citation Format

Share Document