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1.
Tandem stop codons are extra stop codons hypothesized to be present downstream of genes to act as a backup in case of read-through
of the real stop codon. Although seemingly absent from Escherichia coli, recent studies have confirmed the presence of such codons in yeast. In this paper we will analyze the genomes of two ciliate
species—Paramecium tetraurelia and Tetrahymena thermophila—that reassign the stop codons TAA and TAG to glutamine, for the presence of tandem stop codons. We show that there are more
tandem stop codons downstream of both Paramecium and Tetrahymena genes than expected by chance given the base composition of the downstream regions. This excess of tandem stop codons is
larger in Tetrahymena and Paramecium than in yeast. We propose that this might be caused by a higher frequency of stop codon read-through in these species than
in yeast, possibly because of a leaky termination machinery resulting from stop codon reassignment. 相似文献
2.
In response to osmotic stress, proline is accumulated in many bacterial and plant cells. During various stresses, the yeast
Saccharomyces cerevisiae induces glycerol or trehalose synthesis, but the fluctuations in gene expression and intracellular levels of proline in yeast
are not yet well understood. We previously found that proline protects yeast cells from damage by freezing, oxidative, or
ethanol stress. In this study, we examined the relationships between the gene expression profiles and intracellular contents
of glycerol, trehalose, and proline under stress conditions. When yeast cells were exposed to 1 M sorbitol stress, the expression
of GPD1 encoding glycerol-3-phosphate dehydrogenase is induced, leading to glycerol accumulation. In contrast, in the presence of
9% ethanol, the rapid induction of TPS2 encoding trehalose-6-phosphate phosphatase resulted in trehalose accumulation. We found that intracellular proline levels
did not increase immediately after addition of sorbitol or ethanol. However, the expressions of genes involved in proline
synthesis and degradation did not change during exposure to these stresses. It appears that the elevated proline levels are
due primarily to an increase in proline uptake from a nutrient medium caused by the induction of PUT4. These results suggest that S. cerevisiae cells do not accumulate proline in response to sorbitol or ethanol stress different from other organisms. 相似文献
3.
M. Martinez-Pacheco G. Rodriguez G. Reyna C. Calvo-Mendez J. Ruiz-Herrera 《Archives of microbiology》1988,151(1):10-14
Diamino butanone (DAB), a competitive inhibitor of ornithine decarboxylase (ODC) a key enzyme in polyamine biosynthesis, inhibited the yeast to hyphae transition in Mucor rouxii, induced by transfer from anaerobiosis to aerobiosis, but not the opposite phenomenon. Addition of DAB to anaerobic yeast cells brought about a decrease in ODC and polyamine levels. In these conditions, the aerobic shift produced only a weak increase in ODC activity and no change in polyamine levels. DAB also blocked phorogenesis in M. rouxii and in Phycomyces blakesleeanus. At the effective concentrations DAB did not affect cell growth of either fungus. It is suggested that low, constant levels of ODC and polyamines are necessary for cell growth, and that high transient levels are required during the differentiative steps. DAB, at the concentrations used, affects this last process, but does not interfere with the maintenance level of polyamines.Abbreviations ODC
ornithine decarboxylase
- DAB
1,4-diamino butanone 相似文献
4.
5.
Ikuo Nishida Russell Swinhoe Antoni R. Slabas Norio Murata 《Plant molecular biology》1996,31(2):205-211
CTP: phosphocholine cytidylyltransferase is a rate-limiting enzyme in biosynthesis of phosphatidylcholine in plant cells. We have isolated four cDNAs for the cytidylyltransferase from a root cDNA library of Brassica napus by complementation in a yeast cct mutant. The deduced amino-acid sequences of the B. napus enzymes resembled rat and yeast enzymes in the central domain. Although all cytidylyltransferases ever cloned from B. napus and other organisms were predicted to be structurally hydrophilic, the yeast cct mutant transformed with one of the B. napus cDNA clones restored the cytidylyltransferase activity in the microsomal fraction as well as in the soluble fraction. These results are consistent with a recent view that yeast cells contained a machinery for targeting the yeast cytidylyltransferase to membranes, and may indicate that the B. napus enzyme was compatible with the machinery. 相似文献
6.
S. Türkel 《Microbiology》2006,75(6):639-643
Trehalose and glycogen accumulate in certain yeast species when they are exposed to unfavorable growth conditions. Accumulations
of these reserve carbohydrates in yeasts provide resistance to stress conditions. The results of this study indicate that
certain Pichia species do not accumulate high levels of glycogen and trehalose under normal growth conditions. However, depending on the
Pichia species, both saccharides accumulate at high levels when the Pichia cells are exposed to unfavorable or stress-inducing growth conditions. Growth in glycerol or methanol medium mostly led to
trehalose accumulation in Pichia species tested in this study. It was shown that the metabolic pathways for glycogen and trehalose biosynthesis are present
in Pichia species. However, it appears that the biosynthesis of trehalose and glycogen may be regulated in different manners in Pichia species than in the yeast S. cerevisiae.
Published in Russian in Mikrobiologiya, 2006, Vol. 75, No. 6, pp. 737–741.
The text was submitted by the author in English. 相似文献
7.
Patrizia Romano Angela Capece Vincenza Serafino Rossana Romaniello Cinzia Poeta 《World journal of microbiology & biotechnology》2008,24(9):1797-1802
The principal agent in winemaking is the yeast Saccharomyces cerevisiae, which is characterized by a significant strain biodiversity. Here we report the characterization of 80 wild S. cerevisiae strains, isolated from grapes of different varieties in southern Italy, for genetic and technological variability. By PCR
amplification with M13 primer a significant polymorphism was recorded and 12 different biotypes were identified among the
strains. The specific strain-pattern could be used to follow the dynamics of different biotypes during the fermentation process.
The analysis of experimental wines obtained by inoculated fermentations with the 80 strains showed significant differences
among the wines. The level of each compound was a function of the strain performing the fermentative process. The main variables
for the strain differentiation were the production of acetaldehyde and acetic acid, which ranged from 53 to 282 mg/l and from
0.20 to 1.88 g/l, respectively. Selected strains were tested in fermentation with two different grape musts, yielding experimental
wines differing in the levels of secondary compounds and polyphenol content, in function of the interaction “grape must composition/yeast
strain”. This finding has an applicative value for the potentiality of utilizing the resource of strain variability as a tool
to individuate suitable starter cultures, which are able to complement and optimize grape quality. 相似文献
8.
《Bioscience, biotechnology, and biochemistry》2013,77(11):1800-1805
The presence of resveratrol (3,5,4′-trihydroxystilbene) and its β-glucoside, piceid (resveratrol-3-β-D-glucopyranoside), together with their isomers in wine appears to be one of the beneficial factors conferring a protective effect against cardiovascular disease through red wine ingestion. A total of 42 red and white wines was collected in arears from Hokkaido to Kyushu in Japan. The wines were fractionated with a C18 Sep-pak cartridge, and the active principles were eluted with ethyl acetate. Crude trans- and cis-piceid were extracted from a Chinese medicine, ‘Kojohkon’ (Polygonum cuspidatum), and their retention times and UV absorption were confirmed by HPLC. trans- and cis-Resveratrol, and trans- and cis-piceid were analyzed in a short C18 HPLC column, and cis-resveratrol was quantified from the amount of cis-isomer converted from authentic trans-resveratrol that had been treated by UV irradiation. The content of piceid is shown as the resveratrol equivalent. The average content of total stilbene compounds was 4.37mg/liter in red wines, while only 0.68 mg/liter in white wines. Red wines made from Pinot noir, Merlot, and Zweigeltrebe grapes all had a high resveratrol content. 相似文献
9.
N-Acetyltransferase Mpr1 of Saccharomyces cerevisiae can reduce intracellular oxidation levels and protect yeast cells under oxidative stress, including H2O2, heat-shock, or freeze-thaw treatment. Unlike many antioxidant enzyme genes induced in response to oxidative stress, the
MPR1 gene seems to be constitutively expressed in yeast cells. Based on a recent report that ethanol toxicity is correlated with
the production of reactive oxygen species (ROS), we examined here the role of Mpr1 under ethanol stress conditions. The null
mutant of the MPR1 and MPR2 genes showed hypersensitivity to ethanol stress, and the expression of the MPR1 gene conferred stress tolerance. We also found that yeast cells exhibited increased ROS levels during exposure to ethanol
stress, and that Mpr1 protects yeast cells from ethanol stress by reducing intracellular ROS levels. When the MPR1 gene was overexpressed in antioxidant enzyme-deficient mutants, increased resistance to H2O2 or heat shock was observed in cells lacking the CTA1, CTT1, or GPX1 gene encoding catalase A, catalase T, or glutathione peroxidase, respectively. These results suggest that Mpr1 might compensate
the function of enzymes that detoxify H2O2. Hence, Mpr1 has promising potential for the breeding of novel ethanol-tolerant yeast strains. 相似文献
10.
K. V. Kiselev A. P. Tyunin A. Y. Manyakhin Y. N. Zhuravlev 《Plant Cell, Tissue and Organ Culture》2011,105(1):65-72
DNA methylation is known to be involved in the regulation of plant development and defense mechanisms. However, there is a
general lack of data on the role of methylation in plant secondary metabolism. We have investigated the effect of a cytidine
analog, 5-azacytidine (azaC), which is known to block DNA methylation, on resveratrol biosynthesis and stilbene synthase (STS) gene expression in Vitis amurensis cultured cells. Resveratrol is a naturally occurring polyphenol that has been reported to exhibit a wide range of important
biological and pharmacological properties. We previously obtained a control cell line of V. amurensis (VV) as well as a rolB-transgenic cell line of V. amurensis (VB2) that has a higher level of resveratrol accumulation. In our experimental setup, the azaC-treated VV and VB2 calli produced
0.092% and 0.455% dry weight (DW) resveratrol, respectively. We found that treatment with 200 μM of azaC resulted in 1.9-
and 2.0-fold increases in resveratrol production in VV and VB2 calli, respectively. A quantitative real-time PCR assay for
STS gene expression in the azaC-treated VV and VB2 cells revealed that there were statistically increased expression levels of
VaSTS10 in VV calli and of VaSTS5, VaSTS6, and VaSTS10 in VB2 calli. These results demonstrate that azaC is able to increase resveratrol production in V. amurensis calli through a mechanism that involves the induction of STS gene expression. 相似文献
11.
Summary. The cysteine biosynthesis pathway differs between plants and the yeast Saccharomyces cerevisiae. The yeast MET25 gene encoded to O-acetylhomoserine sulfhydrylase (AHS) catalyzed the reaction that form homocysteine, which later can be converted into cystiene.
In vitro studies show that this enzyme possesses also the activity of O-acetyl(thiol)lyase (OASTL) that catalyzes synthesis of cysteine in plants. In this study, we generated transgenic tobacco
plants expressing the yeast MET25 gene under the control of a constitutive promoter and targeted the yeast protein to the cytosol or to the chloroplasts. Both
sets of transgenic plants were taller and greener than wild-type plants. Addition of SO2, the substrate of the yeast enzyme caused a significant elevation of the glutathione content in representative plants from
each of the two sets of transgenic plants expressing the yeast gene. Determination of non-protein thiol content indicated
up to four-folds higher cysteine and 2.5-fold glutathione levels in these plants. In addition, the leaf discs of the transgenic
plants were more tolerant to toxic levels of sulphite, and to paraquat, an herbicide generating active oxygen species. 相似文献
12.
Rehmannia glutinosa L. is an important medicinal crop in Asian countries and contains trace amount of resveratrol compounds. To increase production
of the compounds, we attempted ectopic expression of peanut resveratrol synthase gene (AhRS3) in R. glutinosa. The AhRS3 sequence that encompassed the open reading frame, including a 312 bp-long intron present between the 59th and 60th codon,
was driven by the CaMV35S promoter and introduced into R. glutinosa via Agrobacterium-mediated transformation of leaf explants. The transgenic plants with one to three copies of AhRS3 transgene showed normal growth and development. The transgene was expressed constitutively in the leaf, root and flower at
similar levels. Transgene expression in the leaf resulted in the production of new compounds identified as resveratrol and
3′-H-resveratrol-3-O-β-d-glucoside (R-gluc) through nuclear magnetic resonance spectroscopy and mass spectrometry. R-gluc accumulated predominantly
and its content in the leaf of the 11 transgenic lines ranged from 22 to 116μg/gFW. The contents of resveratrol compounds
in the transgenic plants were further increased by cold, UV, ethylene, and paraquat treatments, and were positively associated
with the levels of AhRS3 mRNA levels. The R-gluc isolated from the transgenic plants exhibited antioxidant activity equivalent to one-third of resveratrol.
Transgenic plants were highly resistant to Fusarium oxysporum infection. The results indicate that the ectopic expression of AhRS3 in R. glutinosa results in the production of R-gluc and resveratrol at hundreds of times higher levels than in peanut seed. The increased
production of resveratrol compounds from R. glutinosa, which show diverse benefits for human and plant health, could provide a new opportunity for the improvement of R. glutinosa products. 相似文献
13.
Dan Gamrasni Ifat Matityahu Rachel Amir 《Molecular breeding : new strategies in plant improvement》2005,15(1):65-74
Methionine biosynthesis has taken different evolutionary pathways in bacteria, fungi and plants. To gain insight into these differences and to search for new ways of manipulating methionine biosynthesis in plants, the yeast (Saccharomyces cerevisiae) Met2 gene and the bacteria (Leptospira meyeri) MetX gene, both encoding homoserine O-acetyltransferase, were expressed in tobacco plants. We found protein aggregates in extracts of these transgenic plants, whose levels were much higher in plants grown at 35 °C than at 25 °C. It appears that the yeast and the bacterial proteins are heat labile and tend to change their intracellular conformation. These conformational changes of the transgenic proteins were more prominent at high temperature and most probably triggered aggregation of the yeast and the bacterial proteins. Moreover, plants expressing the yeast gene that grew at 35 °C over-accumulated stress-associated metabolites, such as phenolic compounds, including tannins, as well as the amino acid arginine. In addition, the transgenic plants expressing high levels of the foreign genes show growth retardation, which further suggests that, these plants suffer from internal stress. The changes in protein conformation and the consequent triggering of stress response may account for the ability of these transgenic plants to tolerate more extreme heat stress (60 °C) than the wild-type plants. 相似文献
14.
We have found that in the alcoholic fermentation of amino acids by yeast isobutyl alcohol is produced from alanine and n-propyl and active amyl alcohols are formed from α-amino-n-butyric acid or threonine contrary to the F. Ehrlich’s scheme. These results suggest the close relationship among the formation of these higher alcohols and biosynthesis of valine from alanine and biosynthesis of isoleucine from α-amino-n-butyric acid or threonine.In this report, we studied the formation of n-propyl alcohol and active amyl alcohol from α-amino-n-butyric acid using washed yeast cells. 相似文献
15.
The diversity of yeast flora was investigated in a spontaneously fermenting sweet white wine in a Tokaj winery. The non-Saccharomyces yeasts dominating the first phase of fermentation were soon replaced by a heterogeneous Saccharomycespopulation, which then became dominated by Saccharomyces bayanus. Three Saccharomyces sensu stricto strains isolated from various phases of fermentation were tested for genetic stability, optimum growth temperature, tolerance to sulphur dioxide, copper and ethanol as well as for the ability to produce hydrogen sulphide and various secondary metabolites known to affect the organoleptic properties of wines. The analysis of the single-spore cultures derived from spores of dissected asci revealed high stability of electrophoretic karyotypes and various degrees of heterozygosity for mating-types, the fermentation of galactose and the production of metabolic by-products. The production levels of the by-products did not segregate in a 2:2 fashion, suggesting that the synthesis of these compounds is under polygenic control. 相似文献
16.
Blanco P Vázquez-Alén M Losada A 《Journal of industrial microbiology & biotechnology》2008,35(3):183-188
This work describes the influence of yeast population on the chemical characteristics of wine obtained by spontaneous and
inoculated fermentation of must from Vitis vinifera Lado, a minor white grapevine autochthonous to Galicia (NW Spain). The study was carried out for two consecutive years. The
results showed that musts derived from Lado presented a high acidity though the potential alcohol level was acceptable. The
genetic diversity of S. cerevisiae strains isolated from spontaneous fermentations was low, probably due to must characteristics, although these did not interfere
with the implantation of the commercial strains used. Analyses showed that the wines subsequently produced had high alcoholic
levels and very high acidities (pH 3.0) as was expected from must composition. Wines obtained from spontaneous fermentations
had a lower alcohol content but higher total acidity than those from inoculated fermentations. Monovarietal wines produced
from Lado were poorly evaluated in sensorial tests because of their unbalanced structure and sourness; however, when they
were mixed with other autochthonous white varieties with less acidity, the resulting wines were well accepted. 相似文献
17.
Summary
Candida stellata is a wine-yeast species that has been proposed for use as a starter in the wine industry in combination with selected Saccharomyces cerevisiae cultures. To improve our knowledge on the metabolic interactions between these two yeast species, we have investigated the
influence of temperature and oxygen concentration on their fermentation behaviour in mixed fermentation. Trials were carried
out with free and immobilized C. stellata cells followed by an inoculum of a commercial strain of S. cerevisiae, to determine the biomass evolution and the oenological profiles of the resulting wines. We show that the oxygen concentration
does not influence the fermentation behaviour of the C. stellata cells, while a low temperature (16 °C) is a critical condition for the metabolic activity of C. stellata in free-cell trials. The immobilization procedures produce a significant improvement in the metabolic activity of C. stellata, with a consequent enhancement of the glycerol content also at the 16 °C fermentation temperature. High cell concentrations
and the immobilization system appear to positively influence the fermentation behaviour of C. stellata. These results are of interest for the practical application of this process in winemaking. 相似文献
18.
Takahashi-Ando N Ochiai N Tokai T Ohsato S Nishiuchi T Yoshida M Fujimura M Kimura M 《Biotechnology letters》2008,30(6):1055-1059
Fusarium Tri4 encodes a key cytochrome P450 monooxygenase for hydroxylation of trichodiene early in the biosynthesis of trichothecenes.
In this study, we established a system for screening for inhibitors of trichothecene biosynthesis using transgenic Saccharomyces cerevisiae expressing Tri4. For easy evaluation of the TRI4 activity, trichodiene-11-one was used as a substrate and the formation of 2α-hydroxytrichodiene-11-one
was monitored by HPLC. Using this system, TRI4 proved to be inhibited by various flavones and furanocoumarins. We also found
that a catechin-containing commercial beverage product, Catechin Supplement 300 (CS300), inhibited TRI4 activity, at a concentration
which did not significantly affect the growth of the transgenic yeast. At an early stage of culture, both flavone and CS300
exhibited a toxin-inhibitory activity against Fusarium graminearum. However, inhibition of trichothecene production was not observed with longer incubation periods at minimum concentrations
necessary to inhibit >50% of the TRI4 activity, presumably due to the metabolism by the fungus. The results suggest that this
yeast screening system with TRI4 is useful for the rapid identification of lead compounds for the design of trichothecene
biosynthesis inhibitors that are resistant to modification by the fungus.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
19.
Dolores Pérez Marie Denat Laura Pérez-Través José María Heras José Manuel Guillamón Vicente Ferreira Amparo Querol 《Microbial biotechnology》2022,15(8):2266-2280
Non-wine yeasts could enhance the aroma and organoleptic profile of wines. However, compared to wine strains, they have specific intolerances to winemaking conditions. To solve this problem, we generated intra- and interspecific hybrids using a non-GMO technique (rare-mating) in which non-wine strains of S. uvarum, S. kudriavzevii and S. cerevisiae species were crossed with a wine S. cerevisiae yeast. The hybrid that inherited the wine yeast mitochondrial showed better fermentation capacities, whereas hybrids carrying the non-wine strain mitotype reduced ethanol levels and increased glycerol, 2,3-butanediol and organic acid production. Moreover, all the hybrids produced several fruity and floral aromas compared to the wine yeast: β-phenylethyl acetate, isobutyl acetate, γ-octalactone, ethyl cinnamate in both varietal wines. Sc × Sk crosses produced three- to sixfold higher polyfunctional mercaptans, 4-mercapto-4-methylpentan-2-one (4MMP) and 3-mercaptohexanol (3MH). We proposed that the exceptional 3MH release observed in an S. cerevisiae × S. kudriavzevii hybrid was due to the cleavage of the non-volatile glutathione precursor (Glt-3MH) to detoxify the cell from the presence of methylglyoxal, a compound related to the high glycerol yield reached by this hybrid. In conclusion, hybrid generation allows us to obtain aromatically improved yeasts concerning their wine parent. In addition, they reduced ethanol and increased organic acids yields, which counteracts climate change effect on grapes. 相似文献
20.
Lopes CA Rodríguez ME Sangorrín M Querol A Caballero AC 《Journal of industrial microbiology & biotechnology》2007,34(2):139-149
In this work we evaluate the implantation capacity of the selected S. cerevisiae indigenous strain MMf9 and the quality of the produced wines in a traditional (T) and a modern (M) cellar with different
ecological and technological characteristics in North Patagonia (Argentina). Red musts were fermented in 10,000 l vats using
the indigenous strain MMf9 as well as the respective controls: a fermentation conducted with a foreign starter culture (BC
strain) in M cellar and a natural fermentation in T cellar. Since commercial S. cerevisiae starters are always used for winemaking in M cellar and in order to compare the results, natural fermentations and fermentations
conducted by the indigenous strain MMf9 were performed at pilot (200 l) scale in this cellar, concomitantly. Thirty indigenous
yeasts were isolated at three stages of fermentation: initial, middle and end. The identification of the yeast biota associated
to vinifications was carried out using ITS1-5.8S-ITS2 PCR-RFLP. The intra-specific variability of the S. cerevisiae populations was evaluated using mtDNA-RFLP analysis. Wines obtained from all fermentations were evaluated for their chemical
and volatile composition and for their sensory characteristics. A higher capacity of implantation of the indigenous MMf9 strain
was evidenced in the fermentation carried out in M cellar (80% at end stage) than the one carried out in T cellar (40%). This
behaviour could indicate that each cellar differs in the diversity of S. cerevisiae strains associated to wine fermentations. Moreover a higher capacity of implantation of the native starter MMf9 with regard
to the foreign (BC) one was also found in M cellar. The selected indigenous strain MMf9 was able to compete with the yeast
biota naturally present in the must. Additionally, a higher rate of sugar consumption and a lower fermentation temperature
were observed in vinifications conducted by MMf9 strain with regard to control fermentations, producing wines with favourable
characteristics. Even when its implantation in T fermentation was lower than that observed in M one, we can conclude that
the wine features from MMf9 fermentations were better than those from their respective controls. Therefore, MMf9 selected
indigenous strain could be an interesting yeast starter culture in North Patagonian wines. 相似文献