scholarly journals Mutations in GCR3, a Gene Involved in the Expression of Glycolytic Genes in Saccharomyces cerevisiae, Suppress the Temperature-Sensitive Growth of hpr1 Mutants

Genetics ◽  
1996 ◽  
Vol 142 (4) ◽  
pp. 1095-1103
Author(s):  
Hiroshi Uemura ◽  
Sunil Pandit ◽  
Yoshifumi Jigami ◽  
Rolf Sternglanz
Keyword(s):  
Topoisomerase I ◽  
Double Mutant ◽  
Genetic Interaction ◽  
Protein A ◽  
Suppressor Gene ◽  
Growth Defect ◽  
Temperature Sensitive ◽  
Triple Mutant ◽  
Dna Topoisomerase ◽  
Cold Sensitive

Abstract To study the functions of DNA topoisomerase I and Hpr1 protein, a suppressor mutant of the temperature-sensitive growth of an hpr1 top1-5ts double mutant was isolated. The isolated triple mutant showed cold-sensitive growth. By complementation of this phenotype, the suppressor gene was cloned. DNA sequencing showed it to be GCR3, a gene involved in the expression of glycolytic genes. Further analysis showed that gcr3 mutations also suppressed the temperature-sensitive growth of hpr1 single mutants. Experiments with gcr3 truncation mutants also suggested a genetic interaction between GCR3 and HPR1. The fact that top1 suppressed the growth defect of gcr3 suggested an interaction between those two genes also. Plasmid DNA isolated from gcr3 mutants was significantly more negatively supercoiled than normal, suggesting that Gcr3 protein, like topoisomerase I and Hpr1p, affects chromatin structure, perhaps during transcription.

scholarly journals Genetic interactions and functional analyses of the fission yeast gsk3 and amk2 single and double mutants defective in TORC1-dependent processes

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Charalampos Rallis ◽  
StJohn Townsend ◽  
Jürg Bähler
Keyword(s):  
Fission Yeast ◽  
Double Mutant ◽  
Genetic Interaction ◽  
Genetic Network ◽  
Cellular Growth ◽  
Regulatory Subunit ◽  
Triple Mutant ◽  
Network Information ◽  
Damage Repair ◽  
Dependent Processes

Abstract The Target of Rapamycin (TOR) signalling network plays important roles in aging and disease. The AMP-activated protein kinase (AMPK) and the Gsk3 kinase inhibit TOR during stress. We performed genetic interaction screens using synthetic genetic arrays (SGA) with gsk3 and amk2 as query mutants, the latter encoding the regulatory subunit of AMPK. We identified 69 negative and 82 positive common genetic interactors, with functions related to cellular growth and stress. The 120 gsk3-specific negative interactors included genes functioning in translation and ribosomes. The 215 amk2-specific negative interactors included genes functioning in chromatin silencing and DNA damage repair. Both amk2- and gsk3-specific interactors were enriched in phenotype categories related to abnormal cell size and shape. We also performed SGA screen with the amk2 gsk3 double mutant as a query. Mutants sensitive to 5-fluorouracil, an anticancer drug are under-represented within the 305 positive interactors specific for the amk2 gsk3 query. The triple-mutant SGA screen showed higher number of negative interactions than the double mutant SGA screens and uncovered additional genetic network information. These results reveal common and specialized roles of AMPK and Gsk3 in mediating TOR-dependent processes, indicating that AMPK and Gsk3 act in parallel to inhibit TOR function in fission yeast.

scholarly journals HPR1 encodes a global positive regulator of transcription in Saccharomyces cerevisiae.

1995 ◽  
Vol 15 (3) ◽  
pp. 1698-1708 ◽  
Author(s):  
Y Zhu ◽  
C L Peterson ◽  
M F Christman
Keyword(s):  
Topoisomerase I ◽  
Gene Dosage ◽  
Normal Growth ◽  
Growth Defect ◽  
Dna Topoisomerase ◽  
Upstream Activation Sequence ◽  
Dam Methylase ◽  
Severe Growth Defect ◽  
Activation Sequence

The Hpr1 protein has an unknown function, although it contains a region of homology to DNA topoisomerase I. We have found that hpr1 null mutants are defective in the transcription of many physiologically unrelated genes, including GAL1, HO, ADH1, and SUC2, by using a combination of Northern (RNA) blot analysis, primer extension, and upstream activation sequence-lacZ fusions. Many of the genes positively regulated by HPR1 also require SWI1, SWI2-SNF2, SWI3, SNF5, and SNF6. The transcriptional defect at HO and the CCB::lacZ upstream activation sequence in hpr1 mutants is partially suppressed by a deletion of SIN1, which encodes an HMG1p-like protein. Elevated gene dosage of either histones H3 and H4 or H2A and H2B results in a severe growth defect in combination with an hpr1 null mutation. However, increased gene dosage of all four histones simultaneously restores near-normal growth in hpr1 mutants. Altered in vivo Dam methylase sensitivity is observed at two HPR1-dependent promoters (GAL1 and SUC2). Most of the Hpr1 protein present in the cell is in a large complex (10(6) Da) that is distinct from the SWI-SNF protein complex. We propose that HPR1 affects transcription and recombination by altering chromatin structure.

scholarly journals Dhh1p, a Putative RNA Helicase, Associates with the General Transcription Factors Pop2p and Ccr4p from Saccharomyces cerevisiae

Genetics ◽  
1998 ◽  
Vol 148 (2) ◽  
pp. 571-579
Author(s):  
Hiroaki Hata ◽  
Hisayuki Mitsui ◽  
Hong Liu ◽  
Yongli Bai ◽  
Clyde L Denis ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Genetic Interaction ◽  
Rna Helicase ◽  
Growth Defect ◽  
Temperature Sensitive ◽  
Phenotypic Analysis ◽  
Multicopy Suppressor ◽  
General Transcription Factors ◽  
Close Relationship ◽  
Partial Suppression

Abstract The POP2 (Caf1) protein in Saccharomyces cerevisiae affects a variety of transcriptional processes and is a component of the Ccr4p complex. We have isolated five multicopy suppressor genes of a pop2 deletion mutation: CCR4, DHH1 (a putative RNA helicase), PKC1, STM1, and MPT5 (multicopy suppressor of pop two). Overexpression of either the CCR4 or DHH1 genes effectively suppressed phenotypes associated with pop2 mutant cells; overexpression of PKC1, STM1, or MPT5 genes produced only partial suppression. Disruption of the CCR4 or DHH1 genes resulted in phenotypes similar to those observed for pop2 cells. In addition, overexpression of the DHH1 gene also suppressed the ccr4 mutation, suggesting a close relationship between the POP2, CCR4, and DHH1 genes. Two-hybrid analysis and coimmunoprecipitation experiments revealed that Pop2p and Dhh1p interact physically, and these and other data suggest that Dhh1p is also a component of the Ccr4p complex. Finally, we investigated the genetic interaction between factors associated with POP2 and the PKC1 pathway. The temperature-sensitive growth defect of dhh1 or mpt5 cells was suppressed by overexpression of PKC1, and the defect of mpk1 cells was suppressed by overexpression of MPT5. These results and phenotypic analysis of double mutants from the POP2 and PKC1 pathways suggested that the POP2 and the PKC1 pathways are independent but have some overlapping functions.

scholarly journals Null alleles of SAC7 suppress temperature-sensitive actin mutations in Saccharomyces cerevisiae.

1990 ◽  
Vol 10 (5) ◽  
pp. 2308-2314 ◽  
Author(s):  
T M Dunn ◽  
D Shortle
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Normal Growth ◽  
Null Alleles ◽  
Growth Defect ◽  
Temperature Sensitive ◽  
Actin Assembly ◽  
New Gene ◽  
Cold Sensitive ◽  
Sensitive Allele ◽  
Extragenic Suppressors

Extragenic suppressors of a new temperature-sensitive mutation (act1-4) in the actin gene of Saccharomyces cerevisiae were isolated in an attempt to identify genes whose products interact directly with actin. One suppressor with a cold-sensitive growth phenotype defined the new gene, SAC7, which was mapped, cloned, sequenced, and disrupted. Genetic analysis of strains that are disrupted for SAC7 demonstrated that the protein is required for normal growth and actin assembly at low temperatures. Surprisingly, null mutations in SAC7 also suppressed the temperature-sensitive growth defect caused by the act1-1 and act1-4 mutations, whereas they were lethal in combination with the temperature-sensitive allele act1-2. These results support the notion that the SAC7 gene product is involved in the normal assembly or function or both of actin.

Null alleles of SAC7 suppress temperature-sensitive actin mutations in Saccharomyces cerevisiae

1990 ◽  
Vol 10 (5) ◽  
pp. 2308-2314
Author(s):  
T M Dunn ◽  
D Shortle
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Normal Growth ◽  
Null Alleles ◽  
Growth Defect ◽  
Temperature Sensitive ◽  
Actin Assembly ◽  
New Gene ◽  
Cold Sensitive ◽  
Sensitive Allele ◽  
Extragenic Suppressors

Extragenic suppressors of a new temperature-sensitive mutation (act1-4) in the actin gene of Saccharomyces cerevisiae were isolated in an attempt to identify genes whose products interact directly with actin. One suppressor with a cold-sensitive growth phenotype defined the new gene, SAC7, which was mapped, cloned, sequenced, and disrupted. Genetic analysis of strains that are disrupted for SAC7 demonstrated that the protein is required for normal growth and actin assembly at low temperatures. Surprisingly, null mutations in SAC7 also suppressed the temperature-sensitive growth defect caused by the act1-1 and act1-4 mutations, whereas they were lethal in combination with the temperature-sensitive allele act1-2. These results support the notion that the SAC7 gene product is involved in the normal assembly or function or both of actin.

Nuclear mutations in Saccharomyces cerevisiae that affect the escape of DNA from mitochondria to the nucleus.

Genetics ◽  
1993 ◽  
Vol 134 (1) ◽  
pp. 21-28 ◽  
Author(s):  
P E Thorsness ◽  
T D Fox
Keyword(s):  
Double Mutant ◽  
Nuclear Dna ◽  
Growth Defect ◽  
Synergistic Interactions ◽  
Mitochondrial Functions ◽  
Origin Of Dna Replication ◽  
Cold Sensitive ◽  
Complementation Groups ◽  
Nuclear Mutations ◽  
Respiratory Deficient

Abstract We have inserted a yeast nuclear DNA fragment bearing the TRP1 gene and its associated origin of DNA replication, ARS1, into the functional mitochondrial chromosome of a strain carrying a chromosomal trp1 deletion. TRP1 was not phenotypically expressed within the organelle. However, this Trp- strain readily gave rise to respiratory competent Trp+ clones that contained the TRP1/ARS1 fragment, associated with portions of mitochondrial DNA (mtDNA), replicating in their nuclei. Thus the Trp+ clones arose as a result of DNA escaping from mitochondria and migrating to the nucleus. We have isolated 21 nuclear mutants in which the rate of mtDNA escape is increased by screening for increased rates of papillation to Trp+. All 21 mutations were recessive and fell into six complementation groups, termed YME1-YME6. In addition to increasing the rate of mtDNA escape, yme1 mutations also caused a heat-sensitive respiratory deficient phenotype at 37 degrees and a cold-sensitive growth defect on complete glucose medium at 14 degrees. While the other yme mutations had no detectable growth phenotypes, synergistic interactions were observed in two double mutant combinations: a yme1, yme2 double mutant failed to respire at 30 degrees and a yme4, yme6 double mutant failed to respire at all temperatures tested. None of the respiratory defects were caused by loss of functional mtDNA. These findings suggest that yme1, yme2, yme4 and yme6 mutations alter mitochondrial functions and thereby lead to an increased rate of DNA escape from the organelle.

Isolation of mutants of Saccharomyces cerevisiae requiring DNA topoisomerase I.

Genetics ◽  
1995 ◽  
Vol 141 (2) ◽  
pp. 465-479 ◽  
Author(s):  
B U Sadoff ◽  
S Heath-Pagliuso ◽  
I B Castaño ◽  
Y Zhu ◽  
F S Kieff ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Rna Polymerase Ii ◽  
Topoisomerase I ◽  
Growth Defect ◽  
Dna Topoisomerase I ◽  
Dna Topoisomerase ◽  
Acid Protein ◽  
Complementation Groups ◽  
Topo Ii ◽  
Null Mutants

Abstract Despite evidence that DNA topoisomerase I is required to relieve torsional stress during DNA replication and transcription, yeast strains with a top1 null mutation are viable and display no gross defects in DNA or RNA synthesis, possibly because other proteins provide overlapping functions. We isolated mutants whose inviablility or growth defect is relieved when TOP1 is expressed [trf mutants (topoisomerase one-requiring function)]. The TRF genes define at least four complementation groups. TRF3 is allelic to TOP2. TRF1 is allelic to HPR1, previously shown to be homologous to TOP1 over two short regions. TRF4 encodes a novel 584-amino acid protein with homology to the N-terminus of Saccharomyces cerevisiae topo I. Like top1 mutants, trf4 mutants have elevated rDNA recombination and fail to shut off RNA polymerase II transcription in stationary phase. trf4 null mutants are cs for viability, display reduced expression of GAL1 and Cell Cycle Box UAS::LacZ fusions, and are inviable in combination with trfI null mutants, indicating that both proteins may share a common function with DNA topoisomerase I. The existence of multiple TRF complementation groups suggests that not all biological functions of topo I can be carried out by topo II.

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