INTERACTION OF THE HIM1 GENE PRODUCT WITH HELICASES Srs2 (RadH) AND Mph1 YEAST SACCHAROMYCES CEREVISIAE

Tsitologiya ◽  
2018 ◽  
Vol 60 (7) ◽  
pp. 555-557 ◽  
Author(s):  
E. A. Alekseeva ◽  
◽  
T. A. Evstyukhina ◽  
V. T. Peshekhonov ◽  
V. G. Korolev ◽  
...  
1992 ◽  
Vol 12 (5) ◽  
pp. 2154-2164 ◽  
Author(s):  
D J DeMarini ◽  
M Winey ◽  
D Ursic ◽  
F Webb ◽  
M R Culbertson

The SEN1 gene, which is essential for growth in the yeast Saccharomyces cerevisiae, is required for endonucleolytic cleavage of introns from all 10 families of precursor tRNAs. A mutation in SEN1 conferring temperature-sensitive lethality also causes in vivo accumulation of pre-tRNAs and a deficiency of in vitro endonuclease activity. Biochemical evidence suggests that the gene product may be one of several components of a nuclear-localized splicing complex. We have cloned the SEN1 gene and characterized the SEN1 mRNA, the SEN1 gene product, the temperature-sensitive sen1-1 mutation, and three SEN1 null alleles. The SEN1 gene corresponds to a 6,336-bp open reading frame coding for a 2,112-amino-acid protein (molecular mass, 239 kDa). Using antisera directed against the C-terminal end of SEN1, we detect a protein corresponding to the predicted molecular weight of SEN1. The SEN1 protein contains a leucine zipper motif, consensus elements for nucleoside triphosphate binding, and a potential nuclear localization signal sequence. The carboxy-terminal 1,214 amino acids of the SEN1 protein are essential for growth, whereas the amino-terminal 898 amino acids are dispensable. A sequence of approximately 500 amino acids located in the essential region of SEN1 has significant similarity to the yeast UPF1 gene product, which is involved in mRNA turnover, and the mouse Mov-10 gene product, whose function is unknown. The mutation that creates the temperature-sensitive sen1-1 allele is located within this 500-amino-acid region, and it causes a substitution for an amino acid that is conserved in all three proteins.


1996 ◽  
Vol 16 (6) ◽  
pp. 2719-2727 ◽  
Author(s):  
S Silve ◽  
P Leplatois ◽  
A Josse ◽  
P H Dupuy ◽  
C Lanau ◽  
...  

SR 31747 is a novel immunosuppressant agent that arrests cell proliferation in the yeast Saccharomyces cerevisiae, SR 31747-treated cells accumulate the same aberrant sterols as those found in a mutant impaired in delta 8- delta 7-sterol isomerase. Sterol isomerase activity is also inhibited by SR 31747 in in vitro assays. Overexpression of the sterol isomerase-encoding gene, ERG2, confers enhanced SR resistance. Cells growing anaerobically on ergosterol-containing medium are not sensitive to SR. Disruption of the sterol isomerase-encoding gene is lethal in cells growing in the absence of exogenous ergosterol, except in SR-resistant mutants lacking either the SUR4 or the FEN1 gene product. The results suggest that sterol isomerase is the target of SR 31747 and that both the SUR4 and FEN1 gene products are required to mediate the proliferation arrest induced by ergosterol depletion.


1992 ◽  
Vol 12 (6) ◽  
pp. 2653-2661
Author(s):  
E Gross ◽  
I Marbach ◽  
D Engelberg ◽  
M Segal ◽  
G Simchen ◽  
...  

The CDC25 gene product of the yeast Saccharomyces cerevisiae has been shown to be a positive regulator of the Ras protein. The high degree of homology between yeast RAS and the mammalian proto-oncogene ras suggests a possible resemblance between the mammalian regulator of Ras and the regulator of the yeast Ras (Cdc25). On the basis of this assumption, we have raised antibodies against the conserved C-terminal domain of the Cdc25 protein in order to identify its mammalian homologs. Anti-Cdc25 antibodies raised against a beta-galactosidase-Cdc25 fusion protein were purified by immunoaffinity chromatography and were shown by immunoblotting to specifically recognize the Cdc25 portion of the antigen and a truncated Cdc25 protein, also expressed in bacteria. These antibodies were shown both by immunoblotting and by immunoprecipitation to recognize the CDC25 gene product in wild-type strains and in strains overexpressing Cdc25. The anti-Cdc25 antibodies potently inhibited the guanyl nucleotide-dependent and, approximately 3-fold less potently, the Mn(2+)-dependent adenylyl cyclase activity in S. cerevisiae. The anti-Cdc25 antibodies do not inhibit cyclase activity in a strain harboring RAS2Val-19 and lacking the CDC25 gene product. These results support the view that Cdc25, Ras2, and Cdc35/Cyr1 proteins are associated in a complex. Using these antibodies, we were able to define the conditions to completely solubilize the Cdc25 protein. The results suggest that the Cdc25 protein is tightly associated with the membrane but is not an intrinsic membrane protein, since only EDTA at pH 12 can solubilize the protein. The anti-Cdc25 antibodies strongly cross-reacted with the C-terminal domain of the Cdc25 yeast homolog, Sdc25. Most interestingly, these antibodies also cross-reacted with mammalian proteins of approximately 150 kDa from various tissues of several species of animals. These interactions were specifically blocked by the beta-galactosidase-Cdc25 fusion protein.


1993 ◽  
Vol 120 (5) ◽  
pp. 1203-1215 ◽  
Author(s):  
K Kuchler ◽  
H G Dohlman ◽  
J Thorner

STE6 gene product is required for secretion of the lipopeptide mating pheromone a-factor by Saccharomyces cerevisiae MATa cells. Radiolabeling and immunoprecipitation, either with specific polyclonal antibodies raised against a TrpE-Ste6 fusion protein or with mAbs that recognize c-myc epitopes in fully functional epitope-tagged Ste6 derivatives, demonstrated that Ste6 is a 145-kD phosphoprotein. Subcellular fractionation, various extraction procedures, and immunoblotting showed that Ste6 is an intrinsic plasma membrane-associated protein. The apparent molecular weight of Ste6 was unaffected by tunicamycin treatment, and the radiolabeled protein did not bind to concanavalin A, indicating that Ste6 is not glycosylated and that glycosylation is not required either for its membrane delivery or its function. The amino acid sequence of Ste6 predicts two ATP-binding folds; correspondingly, Ste6 was photoaffinity-labeled specifically with 8-azido-[alpha-32P]ATP. Indirect immunofluorescence revealed that in exponentially growing MATa cells, the majority of Ste6 showed a patchy distribution within the plasma membrane, but a significant fraction was found concentrated in a number of vesicle-like bodies subtending the plasma membrane. In contrast, in MATa cells exposed to the mating pheromone alpha-factor, which markedly induced Ste6 production, the majority of Ste6 was incorporated into the plasma membrane within the growing tip of the elongating cells. The highly localized insertion of this transporter may establish pronounced anisotropy in a-factor secretion from the MATa cell, and thereby may contribute to the establishment of the cell polarity which restricts partner selection and cell fusion during mating to one MAT alpha cell.


1992 ◽  
Vol 12 (4) ◽  
pp. 1879-1892 ◽  
Author(s):  
J L Davis ◽  
R Kunisawa ◽  
J Thorner

Exposure of a haploid yeast cell to mating pheromone induces transcription of a set of genes. Induction is mediated through a cis-acting DNA sequence found upstream of all pheromone-responsive genes. Although the STE12 gene product binds specifically to this sequence element and is required for maximum levels of both basal and induced transcription, not all pheromone-responsive genes are regulated in an identical manner. To investigate whether additional factors may play a role in transcription of these genes, a genetic screen was used to identify mutants able to express pheromone-responsive genes constitutively in the absence of Ste12. In this way, we identified a recessive, single gene mutation (mot1, for modifier of transcription) which increases the basal level of expression of several, but not all, pheromone-responsive genes. The mot1-1 allele also relaxes the requirement for at least one other class of upstream activating sequence and enhances the expression of another gene not previously thought to be involved in the mating pathway. Cells carrying mot1-1 grow slowly at 30 degrees C and are inviable at 38 degrees C. The MOT1 gene was cloned by complementation of this temperature-sensitive lethality. Construction of a null allele confirmed that MOT1 is an essential gene. MOT1 residues on chromosome XVI and encodes a large protein of 1,867 amino acids which contains all seven of the conserved domains found in known and putative helicases. The product of MOT1 is strikingly homologous to the Saccharomyces cerevisiae SNF2/SW12 and RAD54 gene products over the entire helicase region.


1994 ◽  
Vol 127 (3) ◽  
pp. 623-639 ◽  
Author(s):  
B M Benton ◽  
J H Zang ◽  
J Thorner

The gene (FPR3) encoding a novel type of peptidylpropyl-cis-trans-isomerase (PPIase) was isolated during a search for previously unidentified nuclear proteins in Saccharomyces cerevisiae. PPIases are thought to act in conjunction with protein chaperones because they accelerate the rate of conformational interconversions around proline residues in polypeptides. The FPR3 gene product (Fpr3) is 413 amino acids long. The 111 COOH-terminal residues of Fpr3 share greater than 40% amino acid identity with a particular class of PPIases, termed FK506-binding proteins (FKBPs) because they are the intracellular receptors for two immunosuppressive compounds, rapamycin and FK506. When expressed in and purified from Escherichia coli, both full-length Fpr3 and its isolated COOH-terminal domain exhibit readily detectable PPIase activity. Both fpr3 delta null mutants and cells expressing FPR3 from its own promoter on a multicopy plasmid have no discernible growth phenotype and do not display any alteration in sensitivity to the growth-inhibitory effects of either FK506 or rapamycin. In S. cerevisiae, the gene for a 112-residue cytosolic FKBP (FPR1) and the gene for a 135-residue ER-associated FKBP (FPR2) have been described before. Even fpr1 fpr2 fpr3 triple mutants are viable. However, in cells carrying an fpr1 delta mutation (which confers resistance to rapamycin), overexpression from the GAL1 promoter of the C-terminal domain of Fpr3, but not full-length Fpr3, restored sensitivity to rapamycin. Conversely, overproduction from the GAL1 promoter of full-length Fpr3, but not its COOH-terminal domain, is growth inhibitory in both normal cells and fpr1 delta mutants. In fpr1 delta cells, the toxic effect of Fpr3 overproduction can be reversed by rapamycin. Overproduction of the NH2-terminal domain of Fpr3 is also growth inhibitory in normal cells and fpr1 delta mutants, but this toxicity is not ameliorated in fpr1 delta cells by rapamycin. The NH2-terminal domain of Fpr3 contains long stretches of acidic residues alternating with blocks of basic residues, a structure that resembles sequences found in nucleolar proteins, including S. cerevisiae NSR1 and mammalian nucleolin. Indirect immunofluorescence with polyclonal antibodies raised against either the NH2- or the COOH-terminal segments of Fpr3 expressed in E. coli demonstrated that Fpr3 is located exclusively in the nucleolus.


1991 ◽  
Vol 112 (4) ◽  
pp. 535-544 ◽  
Author(s):  
H B Kim ◽  
B K Haarer ◽  
J R Pringle

Budding cells of the yeast Saccharomyces cerevisiae possess a ring of 10-nm-diameter filaments, of unknown biochemical nature, that lies just inside the plasma membrane in the neck connecting the mother cell to its bud. Electron microscopic observations suggest that these filaments assemble at the budding site coincident with bud emergence and disassemble shortly before cytokinesis (Byers, B. and L. Goetsch. 1976. J. Cell Biol. 69:717-721). Mutants defective in any of four genes (CDC3, CDC10, CDC11, or CDC12) lack these filaments and display a pleiotropic phenotype that involves abnormal bud growth and an inability to complete cytokinesis. We showed previously by immunofluorescence that the CDC12 gene product is probably a constituent of the ring of 10-nm filaments (Haarer, B. and J. Pringle. 1987. Mol. Cell. Biol. 7:3678-3687). We now report the use of fusion proteins to generate polyclonal antibodies specific for the CDC3 gene product. In immunofluorescence experiments, these antibodies decorated the neck regions of wild-type and mutant cells in patterns suggesting that the CDC3 gene product is also a constituent of the ring of 10-nm filaments. We also used the CDC3-specific and CDC12-specific antibodies to investigate the timing of localization of these proteins to the budding site. The results suggest that the CDC3 protein is organized into a ring at the budding site well before bud emergence and remains so organized for some time after cytokinesis. The CDC12 product appears to behave similarly, but may arrive at the budding site closer to the time of bud emergence, and disappear from that site more quickly after cytokinesis, than does the CDC3 product. Examination of mating cells and cells responding to purified mating pheromone revealed novel arrangements of the CDC3 and CDC12 products in the regions of cell wall reorganization. Both proteins were present in normal-looking ring structures at the bases of the first zygotic buds.


1988 ◽  
Vol 8 (7) ◽  
pp. 2980-2983
Author(s):  
J H Camonis ◽  
M Jacquet

In the yeast Saccharomyces cerevisiae, the activation of adenylate cyclase requires the products of the RAS genes and of CDC25. We isolated several dominant extragenic suppressors of the yeast cdc25 mutation. They did not suppress a thermosensitive allele of the adenylate cyclase gene (CDC35). One of these suppressors was a mutated RAS2 gene in which the transition C/G----T/A at position 455 resulted in replacement of threonine 152 by isoleucine in the protein. The same mutation in a v-Ha-ras gene reduces the affinity of p21 for guanine nucleotides (L.A. Feig, B. Pan, T.M. Roberts, and G.M. Cooper, Proc. Natl. Acad. Sci. USA 83:4607-4611, 1986). These results support a model in which the CDC25 gene product is the GDP-GTP exchange factor regulating the activity of the RAS gene product.


1992 ◽  
Vol 12 (5) ◽  
pp. 2154-2164
Author(s):  
D J DeMarini ◽  
M Winey ◽  
D Ursic ◽  
F Webb ◽  
M R Culbertson

The SEN1 gene, which is essential for growth in the yeast Saccharomyces cerevisiae, is required for endonucleolytic cleavage of introns from all 10 families of precursor tRNAs. A mutation in SEN1 conferring temperature-sensitive lethality also causes in vivo accumulation of pre-tRNAs and a deficiency of in vitro endonuclease activity. Biochemical evidence suggests that the gene product may be one of several components of a nuclear-localized splicing complex. We have cloned the SEN1 gene and characterized the SEN1 mRNA, the SEN1 gene product, the temperature-sensitive sen1-1 mutation, and three SEN1 null alleles. The SEN1 gene corresponds to a 6,336-bp open reading frame coding for a 2,112-amino-acid protein (molecular mass, 239 kDa). Using antisera directed against the C-terminal end of SEN1, we detect a protein corresponding to the predicted molecular weight of SEN1. The SEN1 protein contains a leucine zipper motif, consensus elements for nucleoside triphosphate binding, and a potential nuclear localization signal sequence. The carboxy-terminal 1,214 amino acids of the SEN1 protein are essential for growth, whereas the amino-terminal 898 amino acids are dispensable. A sequence of approximately 500 amino acids located in the essential region of SEN1 has significant similarity to the yeast UPF1 gene product, which is involved in mRNA turnover, and the mouse Mov-10 gene product, whose function is unknown. The mutation that creates the temperature-sensitive sen1-1 allele is located within this 500-amino-acid region, and it causes a substitution for an amino acid that is conserved in all three proteins.


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