bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural comparison of the Pichia pastoris alcohol oxidase genes
Authors: Koutz Patricia , Davis Geneva R. , Stillman Cathy , Barringer Kevin , Cregg James , Thill Gregory 
Published: May 2005

AbstractIn methylotrophic yeasts, alcohol oxidase is the first enzyme in the methanol‐utilization pathway. The genome of one such yeast, Pichia pastoris, contains two alcohol oxidase genes, AOX1 and AOX2. Sequence analysis indicated that each gene encodes a similar protein of 663 amino acids. The protein‐coding regions of the genes were 92% and 97% homologous at the nucleotide and predicted amino acid sequence levels, respectively. In contrast to homology observed within the protein‐coding portions of the AOX genes, no homology was found in either the 5′ or 3′ non‐coding regions. Although alcohol oxidase is found in peroxisomes of P. pastoris, the AOX amino acid sequences did not contain a peptide sequence similar to the peroxisomal transport sequence found at the C‐terminus of some peroxisomally located proteins in higher eukaryotes.
Transport of L‐leucine in the fission yeast Schizosaccharomyces pombe
Authors: Sychrová Hana , Horák Jaroslav , Kotyk Arnošt 
Published: May 2005

AbstractTransport of L‐leucine into Schizosaccharomyces pombe cells from the stationary phase of growth (after preincubation for 60 min with 1% glucose) proceeds uphill, practically unidirectionally, and is mediated by at least two systems: a high‐affinity system with a KT of 0·045 mmol 1−1 and Jmax of 3·3 nmol min−1 (mg dry weight)−1 and a low‐affinity system with a KT of 1·25 mmol 1−1 and Jmax of 16·0 nmol min−1 (mg dry weight)−1. The high‐affinity system has a pH optimum at 3.2, the accumulation ratio is highest at a cell density of 2–4 mg dry weight per ml and decreases with increasing leucine concentration. Transport of leucine by the high‐affinity system is strongly inhibited by proton conductors, ammonium ions and by most amino acids, but only L‐phenylalanine, L‐isoleucine, L‐valine and L‐cysteine behave as fully competitive inhibitors. Systems of L‐leucine transport in S. pombe are not constitutive. Transport activity appears only after preincubation of cells with a suitable source of energy. If cycloheximide is added during preincubation with glucose, no transport systems for leucine are synthesized. After removal of glucose, the activity of transport systems decays with a half‐time of about 20 min. The presence of cyclic AMP increases the initial rate of leucine uptake only in cells preincubated with glucose and in the absence of cycloheximide.
Overproduction of glycolytic enzymes in yeast
Authors: Schaaff Ine , Heinisch Jürgen , Zimmermann Friedrich K. 
Published: May 2005

AbstractEight different enzyymes for glycolysis and alcoholic fermentation were overproduced in a common Saccharomyces cerevisiae strain by placing their genes on multicopy vectors. The specific enzyme activities were increased between 3·7‐and 13·9‐fold above the wild‐type level. The overproduction of the different glycolytic enzymes had no effect on the rate of ethanol formation, even with those enzymes that catalyse irreversible steps: hexokinase, phosphofructokinase and pyruvate kinase. Also the simultaneous increase in the activities of pairs of enzymes such as pyruvate kinase and phosphofructokinase or pyruvate decarboxylase and alcohol dehyrogenase, did not increase the rate of ethanol production. The levels of key glycolytic metabolites were also normal, compared to the reference strain.
Intracellular and extracellular levels of cyclic AMP during the cell cycle of Saccharomyces cerevisiae
Authors: Smith Maxine E. , Dickinson J. Richard , Wheals Alan E. 
Published: May 2005

AbstractUsing the techniques of centrifugal elutriation it was demonstrated that during the cell division cycle of the budding yeast Saccharomyces cerevisiae there are stage‐specific fluctuations in the intracellular concentration of adenosine 3′,5′‐cyclic monophosphate (cAMP). Results shown here indicate that the intracellular concentration of cAMP is at its highest during the division cycle, and its lowest immediately prior to and just after cell sepraration. Results also show the extrusion of extracellular cAMP into the medium by Saccharomyces cerevisiae, extracellular cAMP levels being ten to one hundred times higher than intracellular levels. During the cell of Saccharomyces cerevisiae the extracellular level of cAMP does not fluctuate.
A novel aspartyl protease allowing KEX2‐independent MFα propheromone processing in yeast
Authors: Egel‐Mitani Michi , Flygenring Hanne Pia , Hansen Mogens Trier 
Published: May 2005

AbstractMutants of Saccharomyces cerevisiae which lack the KEX2‐encoded endopeptidase are unable to process proteolytically the mating factor alpha (MFα) propheromone produced from the chromosomal MFα1 and MFα2 genes (Julius et al., 1983). Overproduction of pheromone precursor from multiple, plasmid‐borne MFα genes did, however, lead to the production of active MFα peptides in the absence of the KEX2 gene product. S. cerevisiae therefore must possess an alternative processing enzyme. The cleavage site of this enzyme appeared identical to that of the KEX2‐encoded endopeptidase. To identify the gene responsible for the alternative processing, we have isolated clones which allowed production of mature MFα in a kex2‐disrupted strain even from the chromosomal MFα genes. The gene isolated in this way was shown also to be essential for the KEX2‐independent processing of propheromone overproduced from plasmid‐borne MFα1. The amino acid sequence deduced from the gene shows extensive homology to a number of aspartyl proteases including the PEP4 and BARI gene products from S. cerevisiae. In contrast to the BARI gene product, the novel aspartyl protease (YAP3 for Yeast Aspartyl Protease 3) contains a C‐terminal serine/threonine‐rich sequence and potential transmembrane domain similar to those found in the KEX2 gene product. The corresponding gene YAP3 was located to chromosome XII. The normal physiological role of the YAP3 gene product is not known. Strains disrupted in YAP3 are both viable and able to process the mating factor a precursor.
Substrate‐accelerated death of Saccharomyces cerevisiae CBS 8066 under maltose stress
Authors: Postma Erik , Verduyn Cornelis , Kuiper Arthur , Scheffers W. Alexander , Van Dijken Johannes P. 
Published: May 2005

AbstractWhen Saccharomyces cerevisiae CBS 8066 was grown under maltose limitation, two enzymes specific for maltose utilization were present: a maltose carrier, and the maltose‐hydrolysing α‐glucosidase. The role of these two enzymes in the physiology of S. cerevisiae was investigated in a comparative study in which Candida utilis CBS 621 was used as a reference organism.Maltose pulses to a maltose‐limited chemostat culture of S. cerevisiae resulted in ‘substrate‐accelerated death’. This was evident from: (1) enhanced protein release from cells: (2) excretion of glucose into the medium; (3) decreased viability. These effects were specific with respect to both substrate and organism: pulses of glucose to maltose‐limited cultures of S. cerevisiae did not result in cell death, neither did maltose pulses to maltose‐limited cultures of C. utilis. The maltose‐accelerated death of S. cerevisiae is most likely explained in terms of an uncontrolled uptake of maltose into the cell, resulting in an osmotic burst. Our results also provide evidence that the aerobic alcoholic fermentation that occurs after pulsing sugars to sugar‐limited cultures of S. cerevisiae (short‐term Crabtree effect) cannot solely be explained in terms of the mechanism of sugar transport. Both glucose and maltose pulses to maltose‐limited cultures triggered aerobic alcohol formation. However, glucose transport by S. cerevisiae occurs via facilitated diffusion, whereas maltose entry into this yeast is mediated by a maltose/proton symport system.
Osmoregulatory active sodium‐glycerol co‐transport in the halotolerant yeast Debaryomyces hansenii
Authors: Lucas Candida , Da Costa M. , Van Uden N. 
Published: May 2005

AbstractSeveral authors have shown that the halotolerant yeast Debaryomyces hansenii, when growing exponentially in glucose medium in the presence of sodium chloride, maintains osmotic balance by establishing sodium and glycerol gradients of opposite signs across the plasma membrane. Evidence is presented here that the two gradients are linked through a sodium‐glycerol symport that uses the sodium gradient as a driving force for maintaining the glycerol gradient. The symporter also accepts potassium ions as co‐substrate. The kinetic parameters at 25°C, pH 5·0 were the following: Vmax, decreasing from over 500 to less than 40 μmol g−1 per h over a concentration range of 0–3 M extracellular sodium chloride; Km (glycerol) 0·40–0·6 mM over the same range; Km (sodium ions) 16·0 ± 3·21μM; Km, (potassium ions) 10·4 ± 3·6μM. Furthermore, it was observed that glycerol uptake was accompanied by proton uptake when extracellular sodium chloride was present and that the protonophore carbonylcyanide‐M‐chlorophenylhydrazone induced collapse of the glycerol gradient, supporting earlier proposals by others that the sodium gradient is maintained by an active sodium‐proton exchange mechanism.
The alcohol dehydrogenase system in the yeast, Kluyveromyces lactis
Authors: Saliola Michele , Shuster Jeffrey R. , Falcone Claudio 
Published: May 2005

AbstractWe have studied the alcohol dehydrogenase (ADH) system in the yeast Kluyvefromyces lactis. Southern hybridization to the Saccharomyces cerevisiae ADH2 gene indicates four probable structural ADH genes in K. lactis. Two of these genes have been isolated from a genomic bank by hybridization to ADH2. The nucleotide sequence of one of these genes shows 80% and 50% sequence identity to the ADH genes of S. cerevisiae and Schizosaccharomyces pombe respectively. One K. lactis ADH gene is preferentially expressed in glucose‐grown cells and, in analogy to S. cerevisiae, was named K1ADH1. The other gene, homologous to K1ADH1 in sequence, shows an amino‐terminal extension which displays all of the characteristics of a mitochondrial targeting presequence. We named this gene K1ADH3. The two genes have been localized on different chromosomes by Southern hybridization to an orthogonal‐field‐alternation gel electrophoresis‐resolved K. lactis genome. ADH activities resolved by gel electrophoresis revealed several ADH isozymes which are differently expressed in K. lactis cells depending on the carbon source.
Cell fusion of Saccharomyces cerevisiae fragile mutants
Authors: Philipova D. H. , Venkov P. V. 
Published: May 2005

AbstractFragile mutants of Saccharomyces cerevisiae are defective in the structure of the cell wall and plasma membrane. The mutant cells lyse in hypotonic solutions but grow exponentially when osmotic stabilizer is induced in the medium. These mutants display a general increase in the permeability of the plasma membrane. We show here that fragile yeast cells of the same mating type can fuse without protoplast formation. The frequency of cell × cell fusion is lower than that observed for protoplast × protoplast fusion and can be significantly increased if the cells of one partner are converted to protoplasts. Microscopic observations and genetic analysis demonstrate that the hybrids obtained are fusion products. The fusion between fragile cells is explained in terms of the existence of local defects on their surface where the cell wall is thinner (or even missing), thus allowing a direct contact of cells by means of their plasma membranes.
The chromosomal constitution of wine strains of Saccharomyces cerevisiae
Authors: Bakalinsky Alan T. , Snow Richard 
Published: May 2005

AbstractA general procedure is described for determining the chromosomal constitution of industrial strains of Saccharomyces cerevisiae based on analysis of segregation frequencies for input markers among random spore progeny of industrial‐laboratory strain hybrids. The multiple auxotrophic haploid testers used carried a dominant erythromycin‐resistance marker, allowing hybrids to be selected in mass matings with produced by the wild‐type industrial strains. Analysis a number of independent crosses between the haploid testers and an unselected population of spores of each wine strain distinguished between disomic, trisomic and tetrasomic chromosomal complements in the parents. Possible explanations for a significant class of aberrant segregation frequencies are discussed.Results of the analysis indicate that UCD Enology 522 (Montrachet) is diployed and possibly trisomic for chromosome VII; 522X is diploid; UCD Enology 505 (California Champagne) is disomic for chromosome XVI, trisomic for chromosomes I, II, III, VI, VIII, IX, X, XII, XV, tetrasomic for chromosomes IV, XI, XIII, XIV and either trisomic or tetrasomic for chromosomes V and VII; and that UCD Enology 595 (Pasteur Champagne) is disomic for chromosomes I, II, III, IX, XVI, trisomic for chromosomes IV, VI, X, XII, XIV, XV, tetrasomic for chromosomes V, VIII, XI, XIII, and either disomic or tetrasomic for chromosome VII.
III. Yeast sequencing reports. Determination of the sequence of the yeast YCL313 gene localized on chromosome III. Homology with the protein disulfide isomerase (PDI gene product) of other organisms
Authors: Scherens B. , Dubois E. , Messenguy F. 
Published: May 2005

AbstractWe have determined the nucleotide sequence of the YCL313 gene as part of the YIp5 A1G clone localized on the left arm of chromosome III. This YCL313 gene encodes a protein of 522 amino acids (MW 58·3 kDa) which has large homologies with the human, mouse, chicken, bovine and rat PDI gene products. In these organisms the PDI gene encodes the protein disulfide isomerase (EC 5.3.4.1) also called S–S rearrangase, an enzyme that catalyses the rearrangements of S–S bonds in proteins. This enzyme is probably involved in protein folding within the lumen of the endoplasmic reticulum.These sequence homologies suggest that YCL313 is the yeast equivalent of the PDI gene. Gene disruption of YCL313 leads to a lethal phenotype indicating that this gene is essential for cell survival.
A new glucose‐repressible gene identified from the analysis of chromatin structure in deletion mutants of yeast SUC2 locus
Authors: Igual J. Carlos , Matallana Emilia , Gonzalez‐Bosch Carmen , Franco Luis , Pérez‐Ortin José E. 
Published: May 2005

AbstractWe have previously shown that some changes occur in the chromatin structure of the 3′ flank of the yeast SUC2 gene in going from a repressed to an active state. In an attempt to find out the causes of these changes, we have carried out experiments in which mutant copies of SUC2 locus lacking either 5′ or 3′ flanks have been analysed for their transcriptional activity and chromatin structure. These experiments allowed us to discard any relationship between SUC2 transcription and chromatin changes within its 3′ flank. Sequencing of this flank and mRNA analysis, however, resulted in the location of a putative peroxisomal 3‐oxoacyl‐CoA thiolase gene (POT1), which is repressible by glucose. The disruption of the gene produced a yeast strain unable to use oleic acid as a carbon source. This is the first time that chromatin structure analysis has permitted the identification of new gene.
Two genes encoding putative mitochondrial alcohol dehydrogenases are present in the yeast Kluyveromyces lactis
Authors: Saliola Michele , Gonnella Roberta , Mazzoni Cristina , Falcone Claudio 
Published: May 2005

AbstractFour structural genes encoding isozymes of the alcohol dehydrogenase (ADH) system in the yeast Kluyveromyces lactis have been identified by hybridization to ADH2 DNA probes from Saccharomyces cerevisiae. In this paper we report on the isolation of KlADH4 and the complete sequencing of KlADH3 and KlADH4, two genes which show high homology to KlADH1, the ADH gene previously isolated in K. lactis, and to the ADH genes of S. cerevisiae. When compared with KlADH1, both KlADH3 and KlADH4 encode amino‐terminal extensions which show the characteristics of the mitochondrial targeting sequences. These extensions are poorly conserved both at the nucleotide and the amino acid level. Suprisingly, the KlADH4 extension shows a higher identity at the amino acid level to the one encoded by ADH3 of S. cerevisiae than to the KlADH3 presequence. KlADH3 and KlADH4, in contrast to the ADH3 gene of S. cerevisiae, show a strong bias in the choice of codons.
Analysis of the expression and secretion of the Candida tsukubaensis α‐glucosidase gene in the yeast Saccharomyces cerevisiae
Authors: Kinsella B. T. , Cantwell B. A. 
Published: May 2005

AbstractThe α‐glucosidase gene of Candida tsukubaensis is contained within a 3·47 kb BamH1‐Mlu1 fragment which, when introduced into Saccharomyces cerevisiae AH22 on a yeast–Escherichia coli shuttle vector, allows the transformants to utilize maltose as sole carbon source. Thus, the cloned gene confers a dominant selectable phenotype on transformed strains of S. cerevisiae which are otherwise unable to grow in nutrient media containing maltose, dextrin or other α‐1,4‐linked α‐D‐glucopyranosides, specifically hydrolysed by the α‐glucosidase. The cloned enzyme expressed in yeast is secreted into the extracellular medium in a glycosylated form which accounts for up to 60% of the secreted protein and has a molecular size of 70–80 kilodalton (kDa). Deglycosylation of the α‐glucosidase showed that the enzyme is composed of two distinct polypeptides with subunit molecular weights of 63–65 kDa (peptide 1) and 50–52 kDa (peptide 2). An increase in the level of expression of the α‐glucosidase by yeast transformants in selective minimal medium was obtained by using a vector with increased copy number containing the leu2‐d gene as selectable marker. The α‐glucosidase gene promoter functions more effectively than the Gal1–10 promoter in directing α‐glucosidase expression in S. cerevisiae. It also directs the expression of high levels of β‐galactosidase activity in yeast when fused to a promoterless E. coli lacZ gene. Expression of the α‐glucosidase gene under the control of its own promoter is constitutive, orientation dependent and not subject to catabolite repression.
Glucan structure in a fragile mutant of Saccharomyces cerevisiae
Authors: Blagoeva J. , Stoev G. , Venkov P. 
Published: May 2005

AbstractThe phenotype of VY1160 fragile Saccharomyces cerevisiae mutant is characterized by cell lysis upon transfer to hypotonic solutions and increased permeability of cells growing in osmotically stabilized media. Two mutations, srb1 and ts1, have been identified in VY1160 cells and previous studies have shown that the increased permeability is due to the ts1 mutation which causes a shortening of mannan side‐chains. Here we report that the srb1 mutation, which is the genetic determinant of cell lysis, is responsible for quantitative and structural changes of glucans. Experiments with isogenic determinant of cell lysis, is responsible for quantitative and structural changes of glucans. Experiments with isogenic single mutation strains, genetic studies coupled with quantitative measurements of glucan content per cell, and methylation analysis of glucans provide evidence that srb1 mutation leads to (i) formation of mechanically unstable cell wall network made of insoluble glucan fibrils which are shorter and contain β(1–6) inter‐residue linkages and (ii) insufficient filling of the space between the fibrils due to a shortage of the alkali‐soluble glucan. Although growing exponentially in osmotically stabilized media, the srb1 cells cannot resist an osmotic shock and, hence, burst immediately.
Cloning and sequencing of the yeast Saccharomyces cerevisiae SEC1 gene localized on chromosome IV
Authors: Aalto M. K. , Ruohonen L. , Hosono K. , Keränen S. 
Published: May 2005

AbstractThe SEC1 gene of yeast Saccharomyces cerevisiae was cloned by complementing the temperature‐sensitive mutantion of sec1‐1 at 37°C, and its nucleotide sequence was determined. SEC1 is a single copy gene and encodes a protein of 724 amino acids and 83,490 daltons with a predicted pI value of 6·11. Hydrophobicity plotting showed no clearly hydrophobic regions suggesting a soluble nature for the protein. Amino acid sequence comparisons revealed no obvious homologies with the proteins in the SWISSPROT databank. Two consensus sequences for the cdc2 encoded protein kinase recognition site were revealed within Sec1p. The codon usage suggests a low expression level for SEC1. The 5′ non‐translated region contains two TATA‐like sequences at ‐52 and ‐215 nucleotides from the translation start site. Two potential regulatory sequences for DNA binding proteins were found in the non‐coding 5′ region: a HAP2/HAP3 consensus recognition sequence at nucleotide ‐154 and a BAF1 consensus recognition sequence at nucleotide ‐136. The SEC1 specific probe detected a 2400 nucleotides long transcript, which was in reasonable agreement with the 2172 nucleotides long open reading frame.
Repression of a mating type cassette in the fission yeast by four DNA elements
Authors: Ekwall Karl , Nielsen Olaf , Ruusala Tarmo 
Published: May 2005

AbstractThe fission yeast, Schizosaccharomyces pombe, expresses one of two alternative mating types. They are specified by one of two determinants (M or P) present at the mat1 locus. In addition, silent copies of M and P are present on the same chromosome. In the present work we demonstrate that the difference between the active and the silent stage of the P determinant is controlled by four repressive elements that are located at the silent locus. There are two elements to the left and two to the right of the mating type cassette. Both elements to the left and either one of the two elements to the right are required for an effective blockage of transcription. When they are combined, the four elements define a highly efficient silencer functionally similar to the HMRE and HMLE and HMLI silencers in Saccharomyces cerevisiae. In addition, the DNA surrounding the silent P locus confers symmetric partitioning in mitosis to Schizosaccharomyces pombe ars plasmids.
Transport of lactic acid in Kluyveromyces marxianus: Evidence for a monocarboxylate uniport
Authors: Fonseca A. , Spencer‐Martins I. , Van Uden N. 
Published: May 2005

AbstractLactic acid‐grown cells of a strain of Kluyveromyces marxianus transported D‐and L‐lactic acid by a saturable mechanism that was partially inducible and subject to glucose repression, with the following kinetic parameters at pH 5·4: Vmax = 1·00 (±0·13) mmol h−1 per g dry weight and Ks = 0·42 (±0·08) mM. Lactic acid transport was competitively inhibited by pyruvic, glycolic, acetic and bromoacetic acids. The latter, a non‐metabolizable analogue, was transiently accumulated, the extent depending on the extracellular pH. The pH dependence of the Ks values for undissociated lactic acid and for the lactate anion indicated that the latter was the transported species. Lactate uptake was not accompanied by the simulatate uptake of protons, potassium ions or sodium ions excluding symport mechanisms. Initial lactic acid uptake led to transient membrane hyperpolarization as measured with a fluorescent dye excluding also an electroneutral anion antiport mechanism. It was concluded that lactate anions use a monocarboxylate uniport and that the counter anion, possibly bicarbonate, uses a separate channel, the coupling being electrical and loose.
The product of the YCR105 gene located on the chromosome III from Saccharomyces cerevisiae presents homologies to ATP‐dependent permeases
Authors: Purnelle Bénédicte , Skala Jacek , Goffeau André 
Published: May 2005

AbstractDuring the systematic sequencing of chromosome III from Saccharomyces cerevisiae, carried out by a network of laboratories sponsored by the Commission of the European Community, we have identified the open reading frame YCR105 located on fragment J11D from the circular derivative of chromosome III in strain XJ24–24a (Palzkill et al., 1986). YCR105 is immediately centromere proximal to the PGK gene (opposite strand) on the right arm of chromosome III about 20 kb from the centromere.