scholarly journals A MUTATOR AFFECTING THE REGION OF THE ISO-1-CYTOCHROME c GENE IN YEAST

Genetics ◽  
1979 ◽  
Vol 92 (3) ◽  
pp. 783-802 ◽  
Author(s):  
Susan W Liebman ◽  
Arjun Singh ◽  
Fred Sherman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cytochrome C ◽  
Chromosomal Aberrations ◽  
High Rate ◽  
Yeast Saccharomyces Cerevisiae ◽  
Uv Sensitivity ◽  
Mutator Gene ◽  
Mendelian Gene ◽  
Cis And Trans ◽  
Low Rate

ABSTRACT The mutator gene DEL1 in the yeast Saccharomyces cerevisiae cauces a high rate of formation of multisite mutations that encompass the following three adjacent genes: CYC1, which determines the structure of iso-l-cyto-chrome c; RAD7, which controls UV sensitivity; and OSM1, which controls osomotic sensitivity. The simplest hypothesis is that these multisite mutations are deletions, although it has not been excluded that they may involve other types of gross chromosomal aberrations. In contrast, normal strains do not produce such multisite mutations even after mutagenic treatments.——The multisite mutations arise at a rate of approximately 10-5 to 10-6 per cell per division in DEL1 strains, which is much higher than rates observed for mutation of genes in normal strains. For example, normal strains produce all types of cycl mutants at a low rate of approximately 10-8 to 10-9. No evidence for multisite mutations was obtained upon analysis of numerous spontaneous adel, ade2, met2 and met15 mutants isolated in a DEL1 strain. DEL1 segregates as a single Mendelian gene closely linked to the CYC1 locus. DEL1 appears to be both cis- and trans-dominant. The location of the DEL1 gene and the lack of effect on other genes suggest that the mutator acts only on a region adjacent to itself.

scholarly journals DELETIONS OF THE ISO-1-CYTOCHROME c AND ADJACENT GENES OF YEAST: DISCOVERY OF THE OSM1 GENE CONTROLLING OSMOTIC SENSITIVITY

Genetics ◽  
1978 ◽  
Vol 89 (4) ◽  
pp. 653-665
Author(s):  
Arjun Singh ◽  
Fred Sherman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cytochrome C ◽  
Uv Light ◽  
Yeast Saccharomyces Cerevisiae ◽  
Osmotic Sensitivity ◽  
Inhibition Of Growth

ABSTRACT Some of the deletions in the yeast Saccharomyces cerevisiae that encompass the CYC1 gene, which determines iso-1-cytochrome c, extend into the OSM1 gene, causing inhibition of growth on hypertonic media, and into the RAD7 gene, causing sensitivity to UV light. Two deletions (cyc1-363 and cyc1-367) encompass only the CYC1 gene, two deletions (cyc1-366 and cyc1-368) encompass the CYC1 and OSM1 genes, three deletions (cyc1-1, cyc1-364 and cyc1-365) encompass the CYC1, OSM1 and RAD7 genes, while none of the deletions extend into the closely linked SUP4 gene.

scholarly journals cis- and trans-acting suppressors of a translation initiation defect at the cyc1 locus of Saccharomyces cerevisiae.

Genetics ◽  
1992 ◽  
Vol 132 (1) ◽  
pp. 97-112 ◽  
Author(s):  
I Pinto ◽  
J G Na ◽  
F Sherman ◽  
M Hampsey
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cytochrome C ◽  
Point Mutations ◽  
Start Codon ◽  
Reading Frame ◽  
Codon Recognition ◽  
Short Open Reading Frame ◽  
Initiator Codon ◽  
Extragenic Suppressors ◽  
Cis And Trans

Abstract The cyc1-362 mutant of Saccharomyces cerevisiae is deficient in iso-1-cytochrome c as a consequence of an aberrant ATG codon that initiates a short open reading frame (uORF) in the cyc1 transcribed leader region. We have isolated and characterized functional revertants of cyc1-362 in an effort to define cis- and trans-acting factors that can suppress the effect of the uORF. Genetic and DNA sequence analyses have defined three classes of revertants: (i) those that acquired point mutations in the upstream ATG (uATG), restoring iso-1-cytochrome c to its normal level; (ii) substitution of the normal A residue at position -1 relative to the uATG by either C or T, enhancing iso-1-cytochrome c production from approximately 2% to 6% (C) or 10% (T) of normal, indicating that the nucleotide immediately preceding the initiator codon can affect the efficiency of AUG start codon recognition and that purines are preferred over pyrimidines at this site; and (iii) extragenic suppressors that enhance iso-1-cytochrome c expression to 10-40% of normal while retaining the uATG. These suppressors are represented by five different genes, designated sua1-sua4 and sua6. In contrast to the previously described sua7 and sua8 suppressors, they do not compensate for the uATG by affecting cyc1 transcription start site selection. Potential suppressor mechanisms are discussed.

scholarly journals The mechanism for the ATP-induced uncoupling of respiration in mitochondria of the yeast Saccharomyces cerevisiae

1995 ◽  
Vol 307 (3) ◽  
pp. 657-661 ◽  
Author(s):  
S Prieto ◽  
F Bouillaud ◽  
E Rial
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Membrane Potential ◽  
Cytochrome C ◽  
Oxidative Phosphorylation ◽  
Cytochrome C Oxidase ◽  
Kinetic Properties ◽  
Yeast Saccharomyces Cerevisiae ◽  
Saccharomyces Cerevisiae Mitochondria ◽  
Low Efficiency ◽  
Respiratory Chain Activity

We have recently reported that ATP induces an uncoupling pathway in Saccharomyces cerevisiae mitochondria [Prieto, Bouillaud, Ricquier and Rial (1992) Eur. J. Biochem. 208, 487-491]. The presence of this pathway would explain the reported low efficiency of oxidative phosphorylation in S. cerevisiae, and may represent one of the postulated energy-dissipating mechanisms present in these yeasts. In this paper we demonstrate that ATP exerts its action in two steps: first, at low ATP/Pi ratios, it increases the respiratory-chain activity, probably by altering the kinetic properties of cytochrome c oxidase. Second, at higher ATP/Pi ratios, an increase in membrane permeability leads to a collapse in membrane potential. The ATP effect on cytochrome c oxidase corroborates a recent report showing that ATP interacts specifically with yeast cytochrome oxidase, stimulating its activity [Taanman and Capaldi (1993) J. Biol. Chem. 268, 18754-18761].

scholarly journals DEPENDENCE ON MATING TYPE FOR THE OVERPRODUCTION OF ISO-2-CYTOCHROME c IN THE YEAST MUTANT CYC7–H2

Genetics ◽  
1980 ◽  
Vol 94 (4) ◽  
pp. 891-898
Author(s):  
Rodney J Rothstein ◽  
Fred Sherman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cytochrome C ◽  
Mating Type ◽  
Regulatory Region ◽  
The Other ◽  
Yeast Mutant ◽  
Yeast Saccharomyces Cerevisiae ◽  
Type Locus ◽  
Active Expression ◽  
Structural Region

ABSTRACT The CYC7-H2 mutation causes an approximately 20-fold overproduction of iso-2-cytochromo c in a and α haploid strains of the yeast Saccharomyces cerevisiae due to an alteration in the nontranslated regulatory region that is presumably contiguous with the structural region. In this investigation, we demonstrated that heterozygosity at the mating type locus, a /α or a/a/α/α, prevents expression of the overproduction, while homozygosity, a/a and α/α and hemizygosity, a/O and α/O, allow full expression of the CYC7-H2 mutation, equivalent to the expression observed in a and α haploid strains. There is no decrease in the overproduction of iso-2-cytochrome c in a/α diploid strains containing either of the other two similar mutations, CYC7-H1 and CYC7-H3. It appears as if active expression of one or another of the mating-type alleles is required for the overproduction of iso-2-cytochrome c in CYC7-H2 mutants.

mRNA structures influencing translation in the yeast Saccharomyces cerevisiae

1988 ◽  
Vol 8 (4) ◽  
pp. 1591-1601
Author(s):  
S B Baim ◽  
F Sherman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cytochrome C ◽  
Context Effect ◽  
Leader Region ◽  
Mrna Sequence ◽  
Specific Sequence ◽  
Yeast Saccharomyces Cerevisiae ◽  
Initiator Codon ◽  
The Stability ◽  
Nested Deletions

The mRNA sequence and structures that modify and are required for translation of iso-1-cytochrome c in the yeast Saccharomyces cerevisiae were investigated with sets of CYC1 alleles having alterations in the 5' leader region. Measurements of levels of CYC1 mRNA and iso-1-cytochrome c in strains having single copies of altered alleles with nested deletions led to the conclusion that there is no specific sequence adjacent to the AUG initiator codon required for efficient translation. However, the nucleotides preceding the AUG initiator codon at positions -1 and -3 slightly modified the efficiency of translation to an order of preference similar to that found in higher cells. In contrast to large effects observed in higher eucaryotes, the magnitude of this AUG context effect in S. cerevisiae was only two- to threefold. Furthermore, introduction of hairpin structures in the vicinity of the AUG initiator codon inhibited translation, with the degree of inhibition related to the stability and proximity of the hairpin. These results with S. cerevisiae and published findings on other organisms suggest that translation in S. cerevisiae is more sensitive to secondary structures than is translation in higher eucaryotes.

Identification of regulatory regions within the Ty1 transposable element that regulate iso-2-cytochrome c production in the CYC7-H2 yeast mutant

1984 ◽  
Vol 4 (7) ◽  
pp. 1393-1401
Author(s):  
B Errede ◽  
T S Cardillo ◽  
M A Teague ◽  
F Sherman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cytochrome C ◽  
Transposable Element ◽  
Yeast Cells ◽  
Yeast Mutant ◽  
Yeast Saccharomyces Cerevisiae ◽  
Specific Restriction ◽  
Restriction Endonuclease Cleavage

The CYC7-H2 mutation in the yeast Saccharomyces cerevisiae was caused by insertion of a Ty1 transposable element in front of the iso-2-cytochrome c structural gene, CYC7. The Ty1 insertion places iso-2-cytochrome c production under control of regulatory signals that are normally required for mating functions in yeast cells. We have investigated the regions of the Ty1 insertion that are responsible for the aberrant production of iso-2-cytochrome c in the CYC7-H2 mutant. Five alterations of the CYC7-H2 gene were obtained by specific restriction endonuclease cleavage of the cloned DNA and ligation of appropriate fragments. The CYC7+, CYC7-H2, and modified CYC7-H2 genes were each inserted into the yeast vector YIp5 and used to transform a cytochrome c-deficient yeast strain. Expression and regulation of each allele integrated at the CYC7 locus have been compared in vivo by determination of the amount of iso-2-cytochrome c produced. These results show that distal regions of the Ty1 element are not essential for the CYC7-H2 overproducing phenotype. In contrast, alterations in the vicinity of the proximal Ty1 junction abolish the CYC7-H2 expression and give rise to different phenotypes.

scholarly journals A mutation allowing an mRNA secondary structure diminishes translation of Saccharomyces cerevisiae iso-1-cytochrome c.

1985 ◽  
Vol 5 (8) ◽  
pp. 1839-1846 ◽  
Author(s):  
S B Baim ◽  
D F Pietras ◽  
D C Eustice ◽  
F Sherman
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acid ◽  
Secondary Structure ◽  
Cytochrome C ◽  
Mrna Secondary Structure ◽  
Wild Type ◽  
Stable Secondary Structure ◽  
Yeast Saccharomyces Cerevisiae ◽  
Wild Type Level ◽  
Altered Protein

The CYC1-239-O mutation in the yeast Saccharomyces cerevisiae produces a -His-Leu- replacement of the normal -Ala-Gly- sequence at amino acid positions 5 and 6, which lie within a dispensable region of iso-1-cytochrome c; this mutation can accommodate the formation of a hairpin structure at the corresponding site in the mRNA. The amount of the altered protein was diminished to 20% of the wild-type level, whereas the amount of the mRNA remained normal. However, in contrast to the normal CYC1+ mRNA that is associated mainly with four to seven ribosomes, the bulk of the CYC1-239-O mRNA is associated with one to four ribosomes. These results suggest that the stable secondary structure within the translated region of the CYC1 mRNA diminishes translation by inhibiting elongation.

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