Yeast Candida Maltosa Research Articles

Lysine degradation in Candida maltosa: occurrence of a novel enzyme, acetyl-CoA: L-lysine N-acetyltransferase

The yeast Candida maltosa can utilize L-lysine as sole nitrogen and sole carbon source accompanied by accumulation of e-N-acetyl-L-lysine, indicating that lysine is metabolized by way of N-acetylated intermediates. A novel lysine acetyltransferase catalyzing the first step in this pathway, the N-acetylation of the e-amino group of L-lysine, was found in this yeast. The enzyme, acetyl-CoA:L-lysine N-acetyltransferase, is strongly induced in cells grown on L-lysine as sole carbon source. The enzyme is specific for both L-lysine and acetyl-CoA. The Km values are 10 mM for L-lysine and 0.33 mM for acetyl-CoA. The enzyme has a maximum activity at pH 8.1.

Post-translational transport of proteins into microsomal membranes of Candida maltosa.

We have isolated from the yeast Candida maltosa microsomal membranes that are active in the translocation of proteins synthesized in cell-free systems derived from C. maltosa, Saccharomyces cerevisiae or wheat germ. Translocation and core glycosylation of prepro-alpha-factor, a secretory protein, were observed with yeast microsomes added during or after translation. The signal peptide is cleaved off. Cytochrome P-450 from C. maltosa, the first integral membrane protein studied in a yeast system, is also inserted both co- and post-translationally into Candida microsomal membranes. Its insertion into canine microsomes occurs efficiently only in a co-translational manner and is dependent on the function of the signal recognition particle.

Purification and Properties of Two Branched-chain Amino Acid Aminotransferases from the Yeast Candida maltosa

Summary Two aminotransferases of Candida maltosa, AT-I and AT-II, which might participate in the biosynthesis of the branched-chain amino acids were separated one from each other and purified using ammonium sulfate fractionation, chromatography on DEAE-cellulose and hydroxylapatite, and gelfiltration. Both enzymes are located in the cytoplasma and have a molecular weight of 93,000. The two enzymes can be distinguished by a number of criteria. AT-II is heat-sensitive, whereas AT-I is relatively heat-stable. The pH optimum for AT-I and AT-II is 8.6 and 8.3, respectively. Their activity is limited to leucine, isoleucine and valine; 2-oxoglutarate is the most active amino acceptor.

Purification and characterization of pyrocatechase from the catecholassimilating yeast Candida maltosa.

Purification and characterization of pyrocatechase from the catecholassimilating yeast Candida maltosa.

N-Alkanes induce the synthesis of cytochrome P-450 mRNA in [formula omitted

In the yeast Candida maltosa the level of cytochrome P-450 was 100–300-fold higher in alkane-grown cells than in glucose-grown ones (detected by a radioimmunoassay). It was shown immunochemically (1) that this was not the result of an assembly of preexisting apoenzyme with the prosthetic heme group. By cell-free translation of total poly(A)RNA in a wheat germ system and subsequent immunoprecipitation it was shown that the amount of mRNA coding for cytochrome P-450 paralleled its concentration in the cell.

Physical mapping and genome organization of mitochondrial DNA from Candida maltosa.

Mitochondrial (mt) DNA of the ascomycetous yeast Candida maltosa was isolated and characterized. The mtDNA is circular and the size estimated from restriction analysis performed with 7 endonucleases was 52 kb pairs. A restriction map was constructed, using the cleavage data of four endonucleases. Using mt genes from Saccharomyces cerevisiae, six structural genes (large rRNA, apocytochrome b, cytochrome c oxidase subunit I and subunit II, ATPase subunit 6 and subunit 9) were located on the C. maltosa chondriome by cross hybridization experiments. The comparison between the mt genomes of C. maltosa and six other yeasts showed differences in the overall genome organization.

A comparative immunological investigation of the alkane hydroxylating cytochrome P-450 from the yeast Candida maltosa

The immunological relations of the cytochrome P-450 from the n-alkane utilizing yeast Candida maltosa to cytochrome P-450 forms of other organisms - yeasts, bacteria and mammalia - were investigated using a solid-phase double-antibody radioimmunoassay. Only the microsomal fraction of other n-alkane utilizing yeasts shows a distinct cross-reaction with an antiserum against cytochrome P-450 from Candida maltosa. Neither the tested bacterial nor the mammalian cytochromes P-450 cross-react with the antiserum.

Effektor‐ und Precursorfunktion von Mannose‐6‐phosphat, Mannose‐l‐phosphat, UDP‐N‐acetylglucosamin und Dolichylphosphat bei der mikrosomalen Biosynthese von Proteophosphomannan der SCP‐Hefe Candida maltosa H

AbstractMicrosomal preparations from protoplasts of the yeast Candida maltosa, which is able to assimilate n‐alkanes, were used as enzyme source to catalyse the nicorporation of radioactivity from guanosine diphosphate 14C‐mannose, 3H‐mannose‐6‐phosphate, 3H‐mannose‐1‐phosphate or uridine diphosphate N‐acetyl‐(14C‐glucose)‐glusosamine in a mannose polysaccharide. The reaction product was identified as yeast mannan by comparing the saccharides prepared by alkaline degradation and by acetolysis, with those from in vivo proteophosphomannan, obtained in structural investigations.The enzyme preparation catalysed the formation of an almost unsubstituted α(1,6)‐linked mannan backbone from GDP‐Man. Man‐6P, dolichylphosphate and on the other hand UDP‐GNAc in the presence of ATP and dolichylphosphate are potent activators of the mannosyl transfer: α(1,3)‐(and α(1,3)‐) mannosyl transferases are activated by Man‐6P. Beside this Man‐6P is found to be a precursor for the incorporation of the first mannosyl (‐phosphate) unit in the side chain of a branched mannan and of the alkali‐labile bound oligosaccharides.The data presented support the hypothesis that Man‐6P, not activated by GTP, is a second mannosyldonator in the biosynthesis of proteophosphomannan.

Regulation of Tryptophan Biosynthesis in the n-Alkane Utilising Yeast Candida maltosa

Summary The enzymes of tryptophan pathway were partially purified from Candida maltosa and the regulation patterns were established. Ammonia-dependent anthranilate synthase (ASN) (M r 40,000), anthranilate phosphoribosyltransferase (PRT) (M r 100,000), phosphoribosylanthranilate isomerase (PRAI) (M r 30,000), and tryptophan synthase (TS) (M r 140,000) are separated from each other, whereas glutamine-dependent anthranilate synthase (ASG) is active only in complex (M r 75,000) with indole-3-glycerol-phosphate synthase (InGPS). The formation of three enzymes (ASN, PRT, ASG-InGPS) was regulated by the general control of amino acid biosynthesis, whereas synthesis of PRAI and TS was constitutive. Tryptophan only affected both anthranilate synthase activities. The K m -values of ASN were 0.083 mi for chorismate and 10 mM for ammonium. Inhibition of the enzyme reaction by tryptophan was competitive with respect to chorismate (K i = 0.007 mM). The K m -values of ASG were estimated to be 0.043 mM for chorismate and 1.0 mM for glutamine; a K i of 0.004 mM was obtained for tryptophan. A number of tryptophan analogues also inhibited the two enzyme reactions.

Induction and inactivation of phenol hydroxylase and catechol oxygenase in Candida maltosa L4 in dependence on the carbon source

AbstractIn order to investigate the regulation of phenol assimilation in the yeast Candida maltosa L4 the activities of phenol hydroxylase and catechol oxygenase were measured in crude extracts from cells grown in presence of different carbon sources.No activities of these two enzymes have been found in cells grown on glucose, glycerol, succinate or n‐hexadecane. The phenol hydroxylase and catechol oxygenase were induced in presence of phenol. Glucose repressed the induction of both enzymes. The catechol oxygenase appeared only after complete exhaustion of glucose and in the presence of phenol. The phenol hydroxylase was already synthesized in presence of low Incentrations of glucose (<0.2% w/v).Addition of glucose (2% w/v) to a culture of Candida maltosa L4 caused a very rapid disappearance of phenol hydroxylase activity both in the presence of phenol or after depletion of phenol. The catechol oxygenase activity decreased only slowly under these conditions.The inactivation of phenol hydroxylase could be reversed by transferring the glucose‐treated cells into a glucose‐free and phenol‐containing medium. This reappearance of phenol hydroxylase activity could be prevented by the addition of 0.1 mM of cycloheximid, it is, therefore, dependent on de novo protein synthesis.From these results we conclude that the glucose‐dependent catabolite inactivation of phenol hydroxylase in Candida maltosa L4 resulted in a proteolytic degradation of the enzyme.

Genetic analysis of the yeastCandida maltosa by means of induced parasexual processes

The usefulness of hybridization by protoplast fusion and mitotic segregation for the genetic analysis of the imperfect fodder yeastCandida maltosa was tested. Mitotically stable fusion hybrids were obtained with frequencies between 10−6 and 10−7. Complementation tests were performed by protoplast fusion. Substances that are known to induce frequent mitotic segregation in other yeast species such as benomyl, p-fluorophenylalanine, and acriflavine were ineffective inC. maltosa. UV irradiation induced mitotic segregation in up to 10%. This agent induced mainly mitotic crossing over inC. maltosa. Our data enabled the construction of the linkage group I with the sequenceCEN-ade-26-pro-1.

A Solid Phase Radioimmunoassay for Yeast Cytochrwe P-450

Abstract A radioimwunoassay for the quantitation of cytochrome P-450 (cyt P-450) from the yeast Candida maltosa in the microsomab fraction was established using a purified secondary antibody adsorbed to cellulose nitrate discs, a primary rabbit anti (cyt P-450) serum and [125I] labeled cyt P-450. The present assay is highly sensitive, specific and simple, It allows the detection of as little as 5 f moles cyt P-450 in a volume of 40 μ1. Equal immunological reactivities were found for the highly purified, solubilized microsomal, denatured and the apo-form of the yeast cyt P-450.

Ploidy in the asporogenous yeast Candida maltosa, isolation of its auxotrophic mutants and their cell fusion.

Auxotrophic mutants of an asporogenous yeast strain, Candida maltosa IAM12247, were selected after mutagenesis. In spite of our efforts to generate an array of auxotrophic mutants, only two groups of adenine. auxotrophs, histidine auxotrophs and leucine auxotrophs, were obtained. The nuclear DNA content of this species was measured by fluorescent microscope photometry. By this criterion and UV light irradiation inactivation experiments, C. maltosa was found to contain the same ploidy level as diploid strains of Saccharomyces cerevisiae. Unstable intraspecific and intergeneric prototrophic hybrids were obtained by the fusion between auxotrophic mutants of C. maltosa or between auxotrophic mutants of C. maltosa and S. cerevisiae. The stability and relative DNA content of these prototrophic hybrids are compared.