Pichia stipitisL-rhamnose dehydrogenase and a catabolite-resistant mutant able to utilize 2-deoxy-D-glucose

1992 ◽  
Vol 38 (5) ◽  
pp. 417-422 ◽  
Author(s):  
E. H. Pardo ◽  
S. Funayama ◽  
F. O. Pedrosa ◽  
L. U. Rigo
Keyword(s):  
Carbon Source ◽  
Sole Carbon Source ◽  
Glucose Repression ◽  
Resistant Mutant ◽  
Pichia Stipitis ◽  
Enzyme Synthesis ◽  
Selective Medium ◽  
Wild Type ◽  
Dehydrogenase Enzyme ◽  
In The Wild

The yeast Pichia stipitis, strain NRC 5568, when grown on L-rhamnose as sole carbon source produced an NAD+-dependent L-rhamnose dehydrogenase enzyme, which is repressed by D-glucose. Mutants defective in carbon catabolite repression were isolated, using a selective medium containing 2-deoxy-D-glucose. Six of eight mutants resistant to 2-deoxy-D-glucose showed L-rhamnose dehydrogenase synthesis insensitive to D-glucose repression. All eight mutants, named PR mutants, as well as the parent strain, were found to grow on D-glucose, L-rhamnose, and glycerol. In addition, they were all capable of growing on 2-deoxy-D-glucose as sole carbon source, D-Glucose and 2-deoxy-D-glucose caused almost complete inhibition of L-rhamnose dehydrogenase synthesis in the wild-type strain but only a slight decrease in the enzyme synthesis in the mutant strain PR1. The wild-type and mutant strains showed the same pattern of inhibition by cycloheximide, 8-hydroxyquinoline, and benomyl. Key words: Pichia stipitis, L-rhamnose dehydrogenase, catabolite-resistant mutant, 2-deoxy-D-glucose.

scholarly journals Mutants affecting histidine utilization inAspergillus nidulans

1975 ◽  
Vol 25 (2) ◽  
pp. 119-135 ◽  
Author(s):  
Meryl Polkinghorne ◽  
M. J. Hynes
Keyword(s):  
Carbon Source ◽  
Nitrogen Source ◽  
Sole Carbon Source ◽  
Nitrogen Sources ◽  
Limiting Factor ◽  
Sole Nitrogen Source ◽  
Wild Type ◽  
Exogenous Substrate ◽  
Growth Properties ◽  
Type Strains

SUMMARYWild-type strains ofAspergillus nidulansgrow poorly onL-histidine as a sole nitrogen source. The synthesis of the enzyme histidase (EC. 4.3.1.3) appears to be a limiting factor in the growth of the wild type, as strains carrying the mutantareA102 allele have elevated histidase levels and grow strongly on histidine as a sole nitrogen source.L-Histidine is an extremely weak sole carbon source for all strains.Ammonium repression has an important role in the regulation of histidase synthesis and the relief of ammonium repression is dependent on the availability of a good carbon source. The level of histidase synthesis does not respond to the addition of exogenous substrate.Mutants carrying lesions in thesarA orsarB loci (suppressor ofareA102) have been isolated. The growth properties of these mutants on histidine as a sole nitrogen source correlate with the levels of histidase synthesized. Mutation at thesarA andsarB loci also reduces the utilization of a number of other nitrogen sources. The data suggest that these two genes may code for regulatory products involved in nitrogen catabolism. No histidase structural gene mutants were identified and possible explanations of this are discussed.

Selective medium for the isolation and enumeration of Mycobacterium avium-intracellulare and M. scrofulaceum

1986 ◽  
Vol 32 (1) ◽  
pp. 10-14 ◽  
Author(s):  
Karen L. George ◽  
Joseph O. Falkinham III
Keyword(s):  
Carbon Source ◽  
Mycobacterium Avium ◽  
Sole Carbon Source ◽  
Natural Waters ◽  
Tween 80 ◽  
Selective Medium ◽  
Selective Isolation ◽  
Mineral Salts ◽  
Mycobacterium Avium Intracellulare

A medium for the selective isolation and enumeration of Mycobacterium avium-intracellulare and M. scrofulaceum (MAIS) was developed, based upon the ability of these mycobacteria to utilize Tween 80 as sole carbon source and grow optimally at pH 5.5 on a simple mineral salts medium. Representative MAIS strains had higher efficiencies of plating on the Tween 80 medium compared with Middlebrook 7H10. It was shown that nonmycobacterial organisms in natural waters had lower efficiencies of plating on the Tween 80 medium and smaller colonies, thus allowing direct isolation and enumeration of the slowly growing mycobacteria without overgrowth.

scholarly journals Inositol Catabolism, a Key Pathway in Sinorhizobium meliloti for Competitive Host Nodulation

2010 ◽  
Vol 76 (24) ◽  
pp. 7972-7980 ◽  
Author(s):  
Petra R. A. Kohler ◽  
Jasmine Y. Zheng ◽  
Elke Schoffers ◽  
Silvia Rossbach
Keyword(s):  
Bacillus Subtilis ◽  
Carbon Source ◽  
Sole Carbon Source ◽  
Sinorhizobium Meliloti ◽  
Mutational Analysis ◽  
Nodule Occupancy ◽  
Nitrogen Fixing ◽  
Wild Type ◽  
Catabolic Pathway ◽  
Inositol Dehydrogenase

ABSTRACT The nitrogen-fixing symbiont of alfalfa, Sinorhizobium meliloti, is able to use myo-inositol as the sole carbon source. Putative inositol catabolism genes (iolA and iolRCDEB) have been identified in the S. meliloti genome based on their similarities with the Bacillus subtilis iol genes. In this study, functional mutational analysis revealed that the iolA and iolCDEB genes are required for growth not only with the myo-isomer but also for growth with scyllo- and d-chiro-inositol as the sole carbon source. An additional, hypothetical dehydrogenase of the IdhA/MocA/GFO family encoded by the smc01163 gene was found to be essential for growth with scyllo-inositol, whereas the idhA-encoded myo-inositol dehydrogenase was responsible for the oxidation of d-chiro-inositol. The putative regulatory iolR gene, located upstream of iolCDEB, encodes a repressor of the iol genes, negatively regulating the activity of the myo- and the scyllo-inositol dehydrogenases. Mutants with insertions in the iolA, smc01163, and individual iolRCDE genes could not compete against the wild type in a nodule occupancy assay on alfalfa plants. Thus, a functional inositol catabolic pathway and its proper regulation are important nutritional or signaling factors in the S. meliloti-alfalfa symbiosis.

scholarly journals Effects of Chloramphenicol on the Mitochondrial Respiratory Chain in the Wild Strain and in a Cytoplasmic Chloramphenicol-Resistant Mutant ofTetrahymena pyriformis

1982 ◽  
Vol 2 (6) ◽  
pp. 715-719 ◽  
Author(s):  
Roland Perasso ◽  
Jean-Jacques Curgy ◽  
Nicole Stelly ◽  
Jean Andre
Keyword(s):  
Oxygen Consumption ◽  
Cytochrome Oxidase ◽  
Oxidase Activity ◽  
Wild Strain ◽  
Resistant Mutant ◽  
Wild Type ◽  
Mitochondrial Translation ◽  
Cytochrome Oxidase Activity ◽  
In The Wild ◽  
Mitochondrial Respiratory

The effects of chloramphenicol (CAP) on mitochondrial respiratory activity in the wild strain (ST) and in a cytoplasmic CAP-resistant mutant (STR1) ofTetrahymena pyriformiswere studied by determining oxygen consumption, by spectrophotometry, and by cytochemistry. In the absence of CAP both strains had the same respiration capacity, and the low-temperature spectra of their isolated mitochondria were similar. Furthermore, the mitochondria of both strains showed a positive reaction with diaminobenzidine, denoting a similar cytochrome oxidase activity. However, when cells were grown in CAP for 24 or 48 h, the peaks of cytochrome oxidase and cytochromebwere almost absent in the wild type. In this type the oxygen consumption was greatly decreased, and the mitochondria were no longer stained by diaminobenzidine. In the mutant, the peaks of cytochrome oxidase and cytochromebwere decreased only; respiration was less affected than in the wild type, and cytochrome oxidase activity was still disclosed by the diaminobenzidine reaction. These results show that CAP inhibits the synthesis of two cytochromes (band oxidase) which are partially translated into the mitochrondria ofT. pyriformis.In the mutant, CAP reduces only the mitochondrial translation, resulting in reduced mitochondrial activity and reduced growth rate of the cell. These results are compared with the nucleo-mitochondrial regulation mechanisms discussed in our previous works.

scholarly journals ISOLATION AND PROPERTIES OF SELENOMETHIONINE-RESISTANT MUTANTS OF NEUROSPORA CRASSA

Genetics ◽  
1974 ◽  
Vol 77 (4) ◽  
pp. 627-638
Author(s):  
Gregory S Chen ◽  
Robert L Metzenberg
Keyword(s):  
Resistant Mutant ◽  
Heat Stability ◽  
Temperature Sensitive ◽  
Wild Type ◽  
High Concentration ◽  
Type Locus ◽  
Group I ◽  
In The Wild ◽  
Resistant Mutants ◽  
Adenosylmethionine Synthetase

ABSTRACT Mutants resistant to selenomethionine were isolated, and their properties studied. Mapping studies indicate that the mutation sites are located near the eth-1r locus in linkage group I, about ten map units away from the mating type locus. The sites of new mutation are either allelic to or very close to eth-1r. They are resistant not only to selenomethionine but also to ethionine, while the ethionine-resistant mutant, eth-1r, is sensitive to selenomethionine. The selenomethionine-resistant mutants are also temperature-sensitive mutants. However, they can grow at higher temperatures in medium containing 1 M glycerol.—It is very unlikely that the resistance is due to a change in the permeability of the membrane. Aryl sulfatase of se-metr mutants is not repressed by a high concentration of methionine (5 mM), although inorganic sulfate (2 mM) still can cause total repression. The γ-cystathionase levels of the mutants are normal, but the S-adenosylmethionine synthetase levels are only one-tenth of that observed in the wild-type strain. The heat-stability of this enzyme in the mutant is also different from that of the wild-type enzyme suggesting that the mutation might affect the structural gene of S-adenosylmethionine synthetase.

Induction and repression of L-fucose dehydrogenase of Pullularia pullulans

1984 ◽  
Vol 30 (6) ◽  
pp. 753-757 ◽  
Author(s):  
P. F. Conter ◽  
M. F. Guimarães ◽  
L. A. Veiga
Keyword(s):  
Carbon Source ◽  
Sole Carbon Source ◽  
De Novo ◽  
Ring Structure ◽  
Enzyme Synthesis ◽  
De Novo Synthesis

The growth of Pullularia pullulans on L-fucose as the sole carbon source induces the synthesis of L-fucose dehydrogenase, a NAD-dependent enzyme that catalyzes the oxidation of L-fucose to L-fucono-δ-lactone, which spontaneously hydrolyzes to L-fuconic acid. The induction of the enzyme is inhibited by cycloheximide, suggesting de novo synthesis. D-Glucose, D-galactose, and glycerol at 0.5% concentration gave rise to 62, 54, 51, and 46% of repression of enzyme synthesis, respectively. No repression effect was detected with D-arabinose and L-rhamnose. L-Arabinose repressed only 20% of the enzyme synthesis. Among the sugars tested, only L-fucose and L-galactose were oxidized by the enzyme. L-Galactose, which shares a common ring structure with L-fucose, showed only 10% of the activity observed when L-fucose was used.

Phosphatidylinositol phospholipase C mediates carbon sensing and vegetative nuclear duplication rates in Aspergillus nidulans

2011 ◽  
Vol 57 (7) ◽  
pp. 611-616 ◽  
Author(s):  
Ana Paula de Figueiredo Conte Vanzela ◽  
Suraia Said ◽  
Rolf Alexander Prade
Keyword(s):  
Molecular Weight ◽  
Carbon Source ◽  
Phospholipase C ◽  
Aspergillus Nidulans ◽  
Nuclear Division ◽  
Deficient Mutant ◽  
Wild Type ◽  
Pectinolytic Enzymes ◽  
In The Wild ◽  
Phosphatidylinositol Phospholipase C

In this work, we disrupted one of three putative phosphatidylinositol phospholipase C genes of Aspergillus nidulans and studied its effect on carbon source sensing linked to vegetative mitotic nuclear division. We showed that glucose does not affect nuclear division rates during early vegetative conidial germination (6–7 h) in either the wild type or the plcA-deficient mutant. Only after 8 h of cultivation on glucose did the mutant strain present some decrease in nuclear duplication. However, decreased nuclear division rates were observed in the wild type when cultivated in media amended with polypectate, whereas our plcA-deficient mutant did not show slow nuclear duplication rates when grown on this carbon source, even though it requires induction and secretion of multiple pectinolytic enzymes to be metabolized. Thus, plcA appears to be directly linked to high-molecular-weight carbon source sensing.

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