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J. Jiang - One of the best experts on this subject based on the ideXlab platform.

  • Volatile metabolites produced by Kluyveromyces Lactis and their changes during fermentation
    Process Biochemistry, 1995
    Co-Authors: J. Jiang
    Abstract:

    Volatile metabolites produced during Kluyveromyces Lactis fermentation were identified and their kinetics examined. More than 50 compounds identified in the fermentation broth were mainly benzenoid hydrocarbons, alcohols, carboxylic acids, esters, carbonyl and heterocyclic compounds. Predominant components were isoamyl alcohol, isobutanol, 2-phenylethanol, isobutyric acid, isovaleric acid, 2-phenylethyl acetate, 2-phenylethyl isobutyrate and 3-hydroxy-2-butanone. The level of total volatile metabolites increased almost in parallel with biomass during fermentation. The major individual components showed kinetic patterns. Accumulation of carboxylic acids appeared to induce a change in secondary metabolism at a late stage of fermentation. © 1995.

  • Identification of flavour volatile compounds produced by Kluyveromyces Lactis
    Biotechnology Techniques, 1993
    Co-Authors: J. Jiang
    Abstract:

    More than 30 compounds were identified in Kluyveromyces Lactis culture, including 5 aromatic hydrocarbons, 9 alcohols, 6 carboxylic acids, 8 esters, 2 ketones and 1 fuanone. Most of them have not been previously reported in the culture of K. Lactis. The predominant components are isoamyl alcohol, 2-phenylethanol, and acetoin (73, 72 and 22 mg/L broth, respectively). 2-Phenylethyl acetate, isobutanol, isobutyric and isovaleric acids were also detected in significant amounts.

M. E. Cerdán - One of the best experts on this subject based on the ideXlab platform.

  • A transcriptome analysis of Kluyveromyces Lactis growing in cheese whey
    International Dairy Journal, 2006
    Co-Authors: Manuel Becerra, M. Isabel González-siso, M. E. Cerdán
    Abstract:

    Heterologous DNA-arrays from Saccharomyces cerevisiae were used to study the changes of the Kluyveromyces Lactis transcriptome when this yeast was grown in cheese whey (CW) rather than in synthetic media. The results revealed a complete rearrangement in the expression of genes related to glycosylation and secretion pathways when the growth medium was changed. The yeast system was also used to test the advantages of whey supplements as antioxidant protectors. Growth of K. Lactis in CW did not cause an increase in transcription of genes related to glutathione biosynthesis. However, other genes, related to glutathione metabolism and the oxidative stress response, were over expressed in this medium.

  • Heme-mediated transcriptional control in Kluyveromyces Lactis.
    Current genetics, 2000
    Co-Authors: Monica Gonzalez-dominguez, María Angeles Freire-picos, E. Ramil, Bernard Guiard, M. E. Cerdán
    Abstract:

    Heme is of great importance in oxygen-dependent biological functions, since it serves as a prosthetic group for many proteins related to oxygen-binding, oxidative damage prevention and electron transport. It also regulates gene expression through the action of specific transcriptional regulatory factors. In this paper, we present an analysis of heme-dependent transcriptional regulation of several respiration-related genes in an aerobic respiratory yeast, Kluyveromyces Lactis. We also report that the KlHEM13 gene, encoding the heme biosynthetic enzyme coproporphyrinogen oxidase, is under heme and oxygen transcriptional regulation, thereby controlling the synthesis of the effector, heme. KlHEM13 is induced during hypoxia, which represents the first report of a transcriptionally regulated gene with this behaviour in K. Lactis.

Hiroshi Fukuhara - One of the best experts on this subject based on the ideXlab platform.

  • Thematic issue on Kluyveromyces Lactis
    FEMS Yeast Research, 2007
    Co-Authors: Hiroshi Fukuhara, Teun Boekhout
    Abstract:

    This is the second thematic issue of FEMS Yeast Research dedicated to Kluyveromyces Lactis , following the first one that appeared last year ( FEMS Yeast Res Vol. 6, part 3, 2006). In view of the increasing interest in this particular species in yeast research, many readers may find occasional reviews of this field to be useful. The basic metabolism of K. Lactis lies between the typically fermentative Saccharomyces cerevisiae and the nonfermentative species like Cryptococcus spp. and Yarrowia lipolytica . …

  • Kluyveromyces Lactis– a retrospective
    FEMS yeast research, 2006
    Co-Authors: Hiroshi Fukuhara
    Abstract:

    The use of Kluyveromyces Lactis for research started in early 1960s. In contrast to most cases of yeast research, the study of this particular species was initially motivated by a purely academic question, that is, possible adaptive regulation of sugar metabolism in a lower eukaryote. Biotechnological interest in K. Lactis came much later. Until about 1980, K. Lactis research was barely visible in the shadow of the formidable development of the Saccharomyces cerevisiae system. The early 1960s were the era of lactose regulation in Escherichia coli , which led to the birth of molecular biology. Following the achievements of the investigators of the E. coli system, a number of laboratories were trying to find an inducible enzyme system in a eukaryotic organism in order to evaluate the general significance of the operon concept. Harlyn O. Halvorson at Madison, Wisconsin, was one of those people. He contacted the great taxonomist L. J. Wickerham (USDA, Peoria) who knew how different yeast species assimilated various sugars. Apparently, it was he who suggested the use of K. Lactis , a species that assimilated β-glucosides in an adaptive mode. Halvorson and his colleagues have thus started to work on this yeast (then called Saccharomyces Lactis ), using two isolates obtained from Peoria, NRRL Y-1140 (CBS 2359 [ Mat a ]) and …

  • The ubiquitin-encoding genes of Kluyveromyces Lactis.
    Yeast (Chichester England), 2000
    Co-Authors: Wei-guo Bao, Hiroshi Fukuhara
    Abstract:

    The ubiquitin encoding genes of Kluyveromyces Lactis were cloned. Three genes, KlUBI1, KlUBI3 and KlUBI4, were found in this yeast, while in Saccharomyces cerevisiae there are four genes, UBI1, -2, -3 and -4. The UBI1/UBI2 duplication is thus absent from the K. Lactis genome. General structural features of ubiquitin genes were very similar in these two species (presence of an intron in KlUBI1, fusion to ribosomal protein genes in KlUBI1 and KlUBI3, spacer-less polyubiquitin repeats in KlUBI4). Disruption or deletion of K. Lactis ubiquitin genes showed that: (a) disruption of KlUBI1 was lethal (in S. cerevisiae, ubi1/ubi2 double deletion is lethal); (b) KlUBI3 is also an essential gene for cell growth; (c) deletion of KlUBI4 led to an increased sensitivity to high temperature, similar to the ubi4 mutation in S. cerevisiae, but, in contrast to the latter, the klubi4 mutant was not sensitive to carbon or nitrogen source starvation. The syntenic relationship of ubiquitin loci between K. Lactis and S. cerevisiae genomes is also described.

  • The respiratory system of Kluyveromyces Lactis escapes from HAP2 control
    Gene, 1995
    Co-Authors: C. Nguyen, M. Wésolowski-louvel, Monique Bolotin-fukuhara, Hiroshi Fukuhara
    Abstract:

    A functional homolog of the Saccharomyces cerevisiae HAP2 gene, coding for one element of a transcriptional activator complex, was cloned from the yeast Kluyveromyces Lactis and its nucleotide sequence was determined. Inactivation of the gene had no significant effect on respiration-dependent growth, suggesting that the HAP2/3/4 complex has no major control over the formation of the mitochondrial respiratory system in K. Lactis.

  • LEU2 gene homolog in Kluyveromyces Lactis.
    Yeast (Chichester England), 1992
    Co-Authors: Ying-pei Zhang, Xin-jie Chen, Hiroshi Fukuhara
    Abstract:

    A DNA fragment that can complement the leu2 mutation of Saccharomyces cerevisiae was cloned from the genomic library of Kluyveromyces Lactis. The nucleotide sequence revealed an open reading frame of 362 codons, 75% homologous to S. cerevisiae LEU2 gene. The upstream region contained a CCGGAACCGG sequence identical to the site of leucine-specific control of LEU2. Further upstream, there is a partial open reading frame homologous to rat ribosmal protien L7.

Stephan König - One of the best experts on this subject based on the ideXlab platform.

  • The crystal structure of pyruvate decarboxylase from Kluyveromyces Lactis
    The FEBS journal, 2006
    Co-Authors: Steffen Kutter, Georg Wille, Sandy Relle, Manfred S. Weiss, Gerhard Hübner, Stephan König
    Abstract:

    The crystal structure of pyruvate decarboxylase from Kluyveromyces Lactis has been determined to 2.26 A resolution. Like other yeast enzymes, Kluyveromyces Lactis pyruvate decarboxylase is subject to allosteric substrate activation. Binding of substrate at a regulatory site induces catalytic activity. This process is accompanied by conformational changes and subunit rearrangements. In the nonactivated form of the corresponding enzyme from Saccharomyces cerevisiae, all active sites are solvent accessible due to the high flexibility of loop regions 106-113 and 292-301. The binding of the activator pyruvamide arrests these loops. Consequently, two of four active sites become closed. In Kluyveromyces Lactis pyruvate decarboxylase, this half-side closed tetramer is present even without any activator. However, one of the loops (residues 105-113), which are flexible in nonactivated Saccharomyces cerevisiae pyruvate decarboxylase, remains flexible. Even though the tetramer assemblies of both enzyme species are different in the absence of activating agents, their substrate activation kinetics are similar. This implies an equilibrium between the open and the half-side closed state of yeast pyruvate decarboxylase tetramers. The completely open enzyme state is favoured for Saccharomyces cerevisiae pyruvate decarboxylase, whereas the half-side closed form is predominant for Kluyveromyces Lactis pyruvate decarboxylase. Consequently, the structuring of the flexible loop region 105-113 seems to be the crucial step during the substrate activation process of Kluyveromyces Lactis pyruvate decarboxylase.

Manuel Becerra - One of the best experts on this subject based on the ideXlab platform.

  • reoxidation of cytosolic nadph in Kluyveromyces Lactis
    Fems Yeast Research, 2006
    Co-Authors: Nuria Tarrio, M. Esperanza Cerdán, Manuel Becerra, Maria Isabel Gonzalez Siso
    Abstract:

    Saccharomyces cerevisiae and Kluyveromyces Lactis are considered to be the prototypes of two distinct metabolic models of facultatively-aerobic yeasts: Crabtree-positive/fermentative and Crabtree-negative/respiratory, respectively. Our group had previously proposed that one of the molecular keys supporting this difference lies in the mechanisms involved in the reoxidation of the NADPH produced as a consequence of the activity of the pentose phosphate pathway. It has been demonstrated that a significant part of this reoxidation is carried out in K. Lactis by mitochondrial external alternative dehydrogenases which use NADPH, the enzymes of S. cerevisiae being NADH-specific. Moreover, the NADPH-dependent pathways of response to oxidative stress appear as a feasible alternative that might co-exist with direct mitochondrial reoxidation.

  • A transcriptome analysis of Kluyveromyces Lactis growing in cheese whey
    International Dairy Journal, 2006
    Co-Authors: Manuel Becerra, M. Isabel González-siso, M. E. Cerdán
    Abstract:

    Heterologous DNA-arrays from Saccharomyces cerevisiae were used to study the changes of the Kluyveromyces Lactis transcriptome when this yeast was grown in cheese whey (CW) rather than in synthetic media. The results revealed a complete rearrangement in the expression of genes related to glycosylation and secretion pathways when the growth medium was changed. The yeast system was also used to test the advantages of whey supplements as antioxidant protectors. Growth of K. Lactis in CW did not cause an increase in transcription of genes related to glutathione biosynthesis. However, other genes, related to glutathione metabolism and the oxidative stress response, were over expressed in this medium.

  • Functional characterization of KlHEM13, a hypoxic gene of Kluyveromyces Lactis
    Canadian Journal of Microbiology, 2005
    Co-Authors: Moisés Blanco, M. Isabel González-siso, Manuel Becerra, M. Esperanza Cerdán
    Abstract:

    The KlHEM13 gene of Kluyveromyces Lactis encoding the coproporphyrinogen oxidase (EC 1.3.3.3), an oxygen-requiring enzyme that catalyzes the sixth step of heme biosynthesis, was cloned and functionally characterized. The coding and upstream regions of KlHEM13 were analyzed and the putative cis regulatory elements were discussed in relation to the mechanisms of regulation of this hypoxic gene in K. Lactis.Key words: coproporphyrinogen oxidase (CPO), HEM13, hypoxic genes, Kluyveromyces Lactis.

  • Genome-wide analysis of Kluyveromyces Lactis in wild-type and rag2 mutant strains
    Genome, 2004
    Co-Authors: Manuel Becerra, M. Isabel González-siso, Nuria Tarrio, M. Esperanza Cerdán
    Abstract:

    The use of heterologous DNA arrays from Saccharomyces cerevisiae has been tested and revealed as a suitable tool to compare the transcriptomes of S. cerevisiae and Kluyveromyces Lactis, two yeasts with notable differences in their respirofermentative metabolism. The arrays have also been applied to study the changes in the K. Lactis transcriptome owing to mutation in the RAG2 gene coding for the glycolytic enzyme phosphoglucose isomerase. Comparison of the rag2 mutant growing in 2% glucose versus 2% fructose has been used as a model to elucidate the importance of transcriptional regulation of metabolic routes, which may be used to reoxidize the NADPH produced in the pentose phosphate pathway. At this transcriptional level, routes related to the oxidative stress response become an interesting alternative for NADPH use.Key words: Kluyveromyces Lactis, transcription, phosphoglucose isomerase, carbohydrate use.

  • Dealing with different methods for Kluyveromyces Lactis β-galactosidase purification
    Biological procedures online, 1998
    Co-Authors: Manuel Becerra, E. Cerdán, M. I. González Siso
    Abstract:

    Several micro-scale chromatography-based procedures for purification of the β-galactosidase from the yeast Kluyveromyces Lactis were assayed. Purified enzyme was suitable to be used as antigen to induce polyclonal antibodies production. Specific staining of non-denaturing PAGE gels with chromogenic substrates allowed the determination of the number of subunits forming the native enzyme.