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B Ono

Publications and source records attributed to B Ono.

At least 37 records · Page 2Linked to original sources
PubMed1991

The cysteine transport system of Saccharomyces cerevisiae.

Although Saccharomyces cerevisiae strains had different cysteine uptake activities, they revealed monophasic uptake kinetics and had the same KT (83.3 microM). The optimal pH of cysteine uptake was between 4.5 and 5.0, but the activity was quickly lost if cells were kept in buffer. When the activity was measured in the growth medium, it increased in the presence of EDTA and greatly decreased in the presence of mercuric chloride. Thioglycol as well as metabolic inhibitors such as dinitrophenol and azide were inhibitory. Homocysteine and methionine were competitive and non-competitive inhibitors, respectively. Cysteamine and cysteic acid were not inhibitory. From these observations, we conclude that the system mediating uptake of cysteine is specific (we thus name it the cysteine transport system) and that the cysteine transport system recognizes not only the SH-group but also amino- and carboxyl-groups. In wild-type strains the cysteine transport system was derepressed only when the cells were incubated without any sulfur source. On the other hand, in cysteine-dependent mutants, cysteine uptake activity increased with increase of exogenous supply of cysteine, glutathione or methionine. From this result, we suspect that the cellular cysteine level is the limiting factor for biosynthesis of the cysteine transport system in cysteine-dependent strains.

Biological Transport↗
PubMed1991

Interactions between chromosomal omnipotent suppressors and extrachromosomal effectors in Saccharomyces cerevisiae.

Chromosomal omnipotent suppressor mutations recovered in psi+ strains of Saccharomyces cerevisiae were brought into psi- cytoplasm. SUP46, SUP138 and SUP139 acted as dominant omnipotent suppressors in the psi- cytoplasm though their suppressor activity was substantially reduced. SUP46 and SUP138 conferred recessive thermosensitivity and antibiotic sensitivity in psi- cytoplasm as in psi+ cytoplasm. On the other hand, sup111 through sup115, which acted as recessive omnipotent suppressors in the psi+ cytoplasm, manifested no, or very low, suppressor activity in the psi- cytoplasm. They, however, still enhanced the efficiency of the SUP29 tRNA suppressor in psi- cytoplasm. A multicopy plasmid carrying the wild-type SUP35 gene enhanced the efficiency of sup111 in psi- cytoplasm.

Extrachromosomal Inheritance↗
PubMed1991

Role of hydrosulfide ions (HS-) in methylmercury resistance in Saccharomyces cerevisiae.

Methylmercury-resistant mutants were obtained from Saccharomyces cerevisiae. They were divided into two complementation groups, met2 (homoserine O-acetyltransferase deficiency) and met15 (enzyme deficiency unknown), as reported previously. It was found that met15 was allelic to met17 (O-acetylserine and O-acetylhomoserine sulfhydrylase deficiency). Methylmercury toxicity was counteracted by exogenously added HS-, and both met2 and met17 (met15) mutants overproduced H2S. On the basis of these results, we conclude that met2 and met17 (met15) cause accumulation of hydrosulfide ions in the cell and that the increased level of hydrosulfide is responsible for detoxification of methylmercury.

Drug Resistance, Microbial↗
PubMed1990

"Alternative self-diploidization" or "ASD" homothallism in Saccharomyces cerevisiae: isolation of a mutant, nuclear-cytoplasmic interaction and endomitotic diploidization.

A mutant of Saccharomyces cerevisiae representing a novel life cycle, named "alternative self-diploidization" or "ASD" homothallism, was obtained fortuitously. In this life cycle, MAT alpha (or MATa) haplophase and MAT alpha/MAT alpha (or MATa/MATa) diplophase alternate. Germinated cells are haploid and mating. They soon become nonmating and sporogenous as they vegetatively grow. They sooner or later diploidize presumably via endomitosis. The diploid cells haploidize via normal meiosis. A single recessive nuclear mutation, named asd 1-1, is responsible for "ASD" homothallism. In the rho 0 cytoplasm, asd 1-1 cells mate even if at a low efficiency and fail to diploidize. Since pet mutations do not have such effects, we conclude that a certain mitochondrial function other than respiration is required for manifestation of "ASD" homothallism. That is, "ASD" homothallism is the result of some sort of nuclear-cytoplasmic interaction.

Cell Nucleus↗
PubMed1989

Susceptibility of erythrocytes from several animal species to Vibrio vulnificus hemolysin.

The hemolytic activity of Vibrio vulnificus hemolysin (VVH) against erythrocytes from several animal species (sheep, horse, cow, rabbit, chicken) was investigated. VVH was active against erythrocytes from all species, but the amount of VVH causing 50% hemolysis under identical conditions (hemolytic susceptibility to VVH) differed. The degree of 125I-labeled VVH (125I-VVH) binding to each erythrocyte species correlated with the susceptibility of the cells to hemolysis. However, marked differences in the binding ability of 125I-VVH were not observed against liposomes constructed with lipids from each erythrocyte membrane. On the other hand, release of hemoglobin (Hb) differed for each of the erythrocyte species despite administration of approximately the same hemolytic VVH concentration to each species. Furthermore, under hypotonic conditions, the stability of each erythrocyte species varied markedly; the more susceptible the erythrocyte to VVH, the more unstable it was under such conditions. These results, therefore, suggest that the susceptibility of erythrocytes to VVH may be closely associated with the binding ability of VVH and erythrocyte membrane stability.

Animals↗
PubMed1989

Two new loci that give rise to dominant omnipotent suppressors in Saccharomyces cerevisiae.

Ten dominant omnipotent suppressors of Saccharomyces cerevisiae, which were previously shown to be different from SUP46, have been examined. Nine are mapped in a region between lys5 and cyh2 on the left arm of chromosome VII. These suppressors, like SUP46, manifest sensitivity to increased temperature and the antibiotics paromomycin and hygromycin B. In addition, they have an identical action spectrum. These results strongly suggest that they are allelic to each other and they are designated SUP138. The tenth is mapped to a position between his1 and arg6 on the right arm of chromosome V. This suppressor, named SUP139, does not manifest temperature sensitivity nor antibiotic sensitivity. SUP139 and SUP138, which are clearly distinguished by means of action spectrum, act on much fewer nonsense mutations than SUP46. It is now clear that dominant omnipotent suppressors arising at a single locus are homogeneous and that their efficiency is locus-dependent. The order of efficiency is SUP46 greater than SUP138 greater than SUP139.

Alleles↗
PubMed1988

Inheritance of chromosome length polymorphisms in Saccharomyces cerevisiae.

Although Saccharomyces cerevisiae strains generally have similar chromosomal band patterns as revealed by pulsed field gel electrophoresis, individual bands often move slightly differently from one strain to the other. Surveying strains from our stock collection, we found that nearly all the bands of a certain pair of strains differed in their mobility. Some of these chromosome length polymorphisms segregated in a 2:2 ratio, indicating that they resulted from single structural alterations (i.e. additions or deletions). One of these was mapped on the right arm of chromosome I. Others did not segregate in a simple 2:2 ratio. That is, there were progenies which had bands not present in either parent. We suggest that these new bands are the products of recombination between homologous chromosomes having two or more structural alterations.

Chromosome Banding↗
PubMed1988

Role of cell wall in Saccharomyces cerevisiae mutants resistant to Hg2+.

Hg2+-resistant mutants were isolated from Saccharomyces cerevisiae. Although they were very much like the parental strains in terms of colony-forming ability, they grew faster than the parental strains in the presence of sublethal doses of Hg2+. The Hg2+-resistant mutations were dominant. They were centromere linked and were divided into two groups by means of recombination; one of the mutations, designated HGR1-1, was mapped on chromosome IV because of its linkage to the TRP1 locus. The Hg2+-resistant mutants took up Hg2+ as much as, or slightly more than, the parental strains did. The mutants and parental strains retained only about 5 and 15%, respectively, of the cell-associated Hg2+ after removal of the cell wall; therefore, the mutants had less spheroplast-associated Hg2+ than did the parental strains. These results indicate that the cell wall plays an important role in protection against Hg2+ by acting as an adsorption filter and that the mutations described confer Hg2+ resistance by increasing the Hg2+-binding capacity of the cell wall.

Biological Transport↗
PubMed1988

Cysteine biosynthesis in Saccharomyces cerevisiae: mutation that confers cystathionine beta-synthase deficiency.

The cys2-1 mutation of Saccharomyces cerevisiae was originally thought to confer cysteine dependence through a serine O-acetyltransferase deficiency. In this study, we show that cys2-1 strains lack not only serine O-acetyltransferase but also cystathionine beta-synthase. However, a prototrophic strain was found to be serine O-acetyltransferase deficient because of a mutation allelic to cys2-1. Moreover, revertants obtained from cys2-1 strains had serine O-acetyltransferase but not cystathionine beta-synthase, whereas transformants obtained by treating a cys2-1 strain with an S. cerevisiae genomic library had cystathionine beta-synthase but not serine O-acetyltransferase. From these observations, we conclude that cys2-1 (serine O-acetyltransferase deficiency) accompanies a very closely linked mutation that causes cystathionine beta-synthase deficiency and that these mutations together confer cysteine dependence. This newly identified mutation is named cys4-1. These results not only support our previous hypothesis that S. cerevisiae has two functional cysteine biosynthetic pathways but also reveal an interesting gene arrangement of the cysteine biosynthetic system.

Acetyltransferases↗
PubMed1987

Saccharomyces cerevisiae strains sensitive to inorganic mercury. III. Tyrosine uptake.

In Saccharomyces cerevisiae, the HGS2-1 allele confers sensitivities to inorganis mercury (Ono and Sakamoto 1985) and to excess fermentable sugars such as glucose (Sakamoto et al. 1985); exogenous tyrosine antagonizes both inorganic mercury and excess glucose. In this study, the inorganic mercury sensitive strain has been shown to have about twice more glucose-1,6-bisphosphate and slightly less pyruvate than the normal strains, suggesting that the inorganic mercury sensitive strain has the reduced aldolase activity. It has been also shown that the growth retarded cells accumulate trehalose, by which the lower level of glucose-6-phosphate in the inorganic mercury sensitive strain is accounted for, and that inorganic mercury, presumably excess glucose also, causes growth inhibition via depletion of cellular tyrosine. The mechanism how cellular tyrosine is depleted by inorganic mercury or excess glucose is accounted for by the facts that (1) the tyrosine uptake activity is decreased with increase of glucose concentration in growth medium, (2) HGS2-1 enhances the effect of glucose on the tyrosine uptake activity, and (3) inorganic mercury inhibits the tyrosine uptake system by binding to its SH-group(s). Thus, it is concluded that the role of tyrosine is not to detoxify inorganic mercury nor excess fermentable sugars but simply to counteract depletion of cellular tyrosine induced by them.

Biological Transport↗
PubMed1986

Recessive nonsense suppressors in Saccharomyces cerevisiae: action spectra, complementation groups and map positions.

Three genes SUP111, SUP112 and SUP113 of Saccharomyces cerevisiae have been identified that can mutate to give recessive omnipotent nonsense suppressors. Alleles of these loci can also act as allosuppressors; that is, different phenotypes, due apparently to different efficiencies of suppression, can result from different alleles at a given locus. The SUP111, SUP112 and SUP113 loci map to the right arms of chromosomes VIII, VII and XIII, respectively.

Chromosome Mapping↗
PubMed1986

Evidence for the presence of a novel biosynthetic pathway for norspermidine in Vibrio.

Enzymatic studies of the cell extracts of Vibrio alginolyticus and V. parahaemolyticus provided evidence that there exists a novel biosynthetic pathway for norspermidine (NH2(CH2)3NH(CH2)3NH2), a major polyamine species. In this pathway, the Schiff base formed between aspartic beta-semialdehyde and 1,3-diaminopropane is first reduced by a NADPH-dependent enzyme to yield "carboxynorspermidine" (NH2(CH2)3NH(CH2)2CH(NH2)COOH), which is in turn decarboxylated by a pyridoxal phosphate dependent enzyme to form norspermidine. The end product and its intermediate were identified by gas chromatography - mass spectrometry. Experiments with L-[U-14C]aspartic acid resulted in appreciable incorporation of the label into norspermidine. Putrescine could replace 1,3-diaminopropane as a substrate to produce spermidine, but at a reduced rate. The enzyme activity was greatly enhanced by dithiothreitol. Since the activity of an aminopropyltransferase that utilizes decarboxylated S-adenosylmethionine as an aminopropyl group donor could not be detected in any of the cell extracts by our assay method, it was concluded that this novel pathway is primarily responsible for producing norspermidine and spermidine in these species.

Aspartic Acid↗
PubMed1985

Saccharomyces cerevisiae strains sensitive to inorganic mercury. I. Effect of tyrosine.

From a cross of two strains of Saccharomyces cerevisiae, both of which had the same (wild type or normal) level of resistance to inorganic mercury, segregants having three distinguishable resistance levels, normal, sensitive and semi-sensitive, were obtained. Genetic analyses of the parents and the progeny indicated that the levels of inorganic mercury sensitivity were determined by three distinct loci, HGS1, HGS2 and MSM1. The recessive allele of the HGS1 locus, hgs1-1, and the codominant allele of the HGS2 locus, HGS2-1, were necessary for the sensitive phenotypes, and alleles in the MSM1 locus, MSM1-1 and msm1-2, were responsible for the different sensitivity levels. In short, the strains of genotypes hgs1-1 HGS2-1 msm1-2 and hgs1-1 HGS2-1 MSM1-1 were sensitive and semi-sensitive, respectively, while the strains of all other genotypes were normal. Although the hgs1-1 allele was identified as the aro7-1 mutation which confers deficiency of tyrosine and phenylalanine, mutations such as aro1B (deficiency of tyrosine, phenylalanine and tryptophan) and tyr1 (deficiency of tyrosine) had similar effects as aro7-1 on inorganic mercury sensitivity. From these results we conclude that the HGS2-1 allele causes inorganic mercury sensitivity when the cells are defective in the tyrosine biosynthesis. In fact, addition of tyrosine to the growth medium containing inorganic mercury resulted in increase of colony forming ability of the sensitive strains.

Culture Media↗
PubMed1985

Saccharomyces cerevisiae strains sensitive to inorganic mercury. II. Effect of glucose.

Saccharomyces cerevisiae strains sensitive to inorganic mercury (Ono and Sakamoto 1985) did not grow well on the medium rich in glucose and poor in peptone. This growth inhibition, like growth inhibition caused by inorganic mercury, was relieved by exogenous tyrosine. Sugars such as fructose and mannose were as inhibitory as glucose, but glycerol was not at all. Galactose was inhibitory but not so much as glucose. A gal2 mutation (defective in galactose uptake) partly relieved growth inhibition caused by excess galactose. Moreover, it was found that some of revertants which gained ability to grow well in the presence of excess glucose were defective in the glucose uptake. From these observations, we conclude that growth inhibition of the inorganic mercury sensitive strains by excess sugar is a consequence of the catabolite regulation. In other words, the inorganic mercury sensitive strains are hyper-sensitive to the catabolite regulation due to the presence of the HGS2-1 allele.

Culture Media↗
PubMed1984

Cystathionine accumulation in Saccharomyces cerevisiae.

A cysteine-dependent strain of Saccharomyces cerevisiae and its prototrophic revertants accumulated cystathionine in cells. The cystathionine accumulation was caused by a single mutation having a high incidence of gene conversion. The mutation was designated cys3 and was shown to cause loss of gamma-cystathionase activity. Cysteine dependence of the initial strain was determined by two linked and interacting mutations, cys3 and cys1 . Since cys1 mutations cause a loss of serine acetyltransferase activity, our observation led to the conclusion that S. cerevisiae synthesizes cysteine by sulfhydrylation of serine with hydrogen sulfide and by cleavage of cystathionine which is synthesized from serine and homocysteine.

Cystathionine↗
PubMed1980

Differences between surface antigenic determinants of polar monotrichous flagella of Vibrio parahaemolyticus and of related species.

Polar monotrichous flagella (M-flagella) of Vibrio parahaemolyticus have antigens in common with those of various species of Vibrio including V. cholerae and V. anguillarum, and of Beneckea, revealed by gel diffusion tests with flagelli monomers. However, antiserum against M-flagellin of V. parahaemolyticus did not agglutinate cells of V. cholerae and V. anguillarum, although it did agglutinate cells of V. parahaemolyticus. Agglutination tests after absorption of the antiserum with purified M-flagellar filaments or flagellin monomers and H-agglutination inhibition tests demonstrated that there are two different antigenic determinants in M-flagella as in lateral flagella. One is on the surface of the M-flagella (surface antigenic determinant, SA) and disappears or is buried in dissociated monomers. The other is inside the flagella (internal antigenic determinant, IA) and is exposed when the flagella are dissociated to flagellin monomers. SA of V. parahaemolyticus is different from those of V. cholerae and V. anguillarum, whereas the three species have a common IA.

Agglutination Tests↗