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1.
Expression of many microbial genes required for the utilisation of less favoured carbon sources is carbon catabolite repressed in the presence of a preferred carbon source such as D-glucose. In Aspergillus nidulans, creC mutants show derepression in the presence of D-glucose of some, but not all, systems normally subject to carbon catabolite repression. These mutants also fail to grow on some carbon sources, and show minor morphological impairment and altered sensitivity to toxic compounds including molybdate and acriflavin. The pleiotropic nature of the phenotype suggests a role for the creC gene product in the carbon regulatory cascade. The creC gene was cloned and found to encode a protein which contains five WD40 motifs. The sequence changes in three mutant alleles were found to lead to production of truncated proteins which lack one or more of the WD40 repeats. The similarity of the phenotypes conferred by these alleles implies that these alleles represent loss of function alleles. Deletion analysis also showed that at least the most C-terminal WD40 motif is required for function. The CreC protein is highly conserved relative to the Schizosaccharomyces pombe protein Yde3 – whose function is unknown – and human and mouse DMR-N9, which may be associated with myotonic dystrophy. 相似文献
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Genetic dissection of carbon catabolite repression in Aspergillus nidulans has identified two genes, creB and creC, which, when mutated, affect expression of many genes in both carbon catabolite repressing and derepressing conditions. The creB gene encodes a functional deubiquitinating enzyme and the creC gene encodes a protein that contains five WD40 repeat motifs, and a proline-rich region. These findings have allowed the in vivo molecular analysis of a cellular switch involving deubiquitination. We demonstrate that overexpression of the CreB deubiquitinating enzyme can partially compensate for a lack of the CreC WD40-repeat protein in the cell, but not vice versa and, thus, the CreB deubiquitinating enzyme acts downstream of the CreC WD40-repeat protein. We demonstrate using co-immunoprecipitation experiments that the CreB deubiquitinating enzyme and the CreC WD40-repeat protein interact in vivo in both carbon catabolite repressing and carbon catabolite derepressing conditions. Further, we show that the CreC WD40-repeat protein is required to prevent the proteolysis of the CreB deubiquitinating enzyme in the absence of carbon catabolite repression. This is the first case in which a regulatory deubiquitinating enzyme has been shown to interact with another protein that is required for the stability of the deubiquitinating enzyme. 相似文献
4.
K. -D. Entian 《Molecular & general genetics : MGG》1981,184(2):278-282
Summary Mutants were investigated that had elevated hexokinase activity and had been isolated previously as resistant to carbon catabolite repression (Zimmermann and Scheel 1977). They were allele tested with mutant strains of Lobo and Maitra (1977), which had defects in one or more of the genes coding for glucokinase and unspecific hexokinases. It was shown, that the mutation abolishing carbon catabolite repression had occured in a gene that was not allelic to any of the structural genes coding for hexokinases. This indicated that a regulatory defect was responsible for elevated hexokinase activity. This agreed with observations that hexokinase activities were like wild-type during growth on non-fermentable carbon sources in hex2 mutants. Recombination between the mutant allele hex2 and mutant alleles hxk1 and hxk2, coding for hexokinase PI and PII respectively, clearly demonstrated that only hexokinase PII was elevated in hex2 mutants. When hex2 mutant cells grown on YEP ethanol were shifted to YEP glucose media, hexokinase activity increased after 30min. This increase depended on de novo protein synthesis. hex2 mutants provide evidence, that carbon catabolite repression and synthesis of hexokinase PII are under common regulatory control. 相似文献
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Peter van der Veen Herbert N. Arst Jr Michel J. A. Flipphi Jaap Visser 《Archives of microbiology》1994,162(6):433-440
The regulation of the syntheses of two arabinan-degrading extracellular enzymes and several intracellular l-arabinose catabolic enzymes was examined in wild-type and carbon catabolite derepressed mutants of Aspergillus nidulans. α-l-Arabinofuranosidase B, endoarabinase, l-arabinose reductase, l-arabitol dehydrogenase, xylitol dehydrogenase, and l-xylulose reductase were all inducible to varying degrees by l-arabinose and l-arabitol and subject to carbon catabolite repression by d-glucose. With the exception of l-xylulose reductase, all were clearly under the control of creA, a negative-acting wide domain regulatory gene mediating carbon catabolite repression. Measurements of intracellular enzyme
activities and of intracellular concentrations of arabitol and xylitol in mycelia grown on d-glucose in the presence of inducer indicated that carbon catabolite repression diminishes, but does not prevent uptake of
inducer. Mutations in creA resulted in an apparently, in some instances very marked, elevated inducibility, perhaps reflecting an element of “self”
catabolite repression by the inducing substrate. creA mutations also resulted in carbon catabolite derepression to varying degrees. The regulatory effects of a mutation in creB and in creC, two genes whose roles are unclear, but likely to be indirect, were, when observable, more modest. As with previous data
showing the effect of creA mutations on structural gene expression, there were striking instances of phenotypic variation amongst creA mutant alleles and this variation followed no discernible pattern, i.e. it was non-hierarchical. This further supports molecular
data obtained elsewhere, indicating a direct role for creA in regulating structural gene expression, and extends the range of activities under creA control. 相似文献
7.
Mahr K van Wezel GP Svensson C Krengel U Bibb MJ Titgemeyer F 《Antonie van Leeuwenhoek》2000,78(3-4):253-261
Glucose kinase of Streptomyces coelicolor A3(2) is essential for glucose utilisation and is required for carbon catabolite repression (CCR) exerted through glucose and other carbon sources. The protein belongs to the ROK-family, which comprises bacterial sugar kinases and regulators. To better understand glucose kinase function, we have monitored the cellular activity and demonstrated that the choice of carbon sources did not significantly change the synthesis and activity of the enzyme. The DNA sequence of the Streptomyces lividans glucose kinase gene glkA was determined. The predicted gene product of 317 amino acids was found to be identical to S. coelicolor glucose kinase, suggesting a similar role for this protein in both organisms. A procedure was developed to produce pure histidine-tagged glucose kinase with a yield of approximately 10 mg/l culture. The protein was stable for several weeks and was used to raise polyclonal antibodies. Purified glucose kinase was used to explore protein-protein interaction by surface plasmon resonance. The experiments revealed the existence of a binding activity present in S. coelicolor cell extracts. This indicated that glucose kinase may interact with (an)other factor(s), most likely of protein nature. A possible cross-talk with proteins of the phosphotransferase system, which are involved in carbon catabolite repression in other bacteria, was investigated. 相似文献
8.
Zhihua Jin Yinlin Lei Jianping Lin Peilin Cen 《World journal of microbiology & biotechnology》2006,22(2):129-134
Summary According to the biosynthetic pathway of pristinamycin, a rational selection procedure with u.v. mutation was performed to obtain a high pristinamycin-producing strain. Aminoacetic acid-resistant mutants (AAr), valine hydroxamate-resistant mutants (VHr), kitasamycin-resistant mutants (KTMr) and 2-deoxy-D-glucose-resistant mutants (DOGr) were selected, successively. A strain Streptomyces pristinaespiralis 12–55 with AAr, Valr, KTMr, and DOGr was obtained, and its production of pristinamycin reached 3000 u/ml which is 100 times higher than that of the parent strain S. pristinaespiralis ATCC 25486. It is inferred that S. pristinaespiralis 12–55 can alleviate catabolite repression caused by carbon sources, provide more acetic acid and valine for pristinamycin biosynthesis and increase its resistance to pristinamycin produced by itself, all of which are favorable for pristinamycin production. The subculture experiments indicated that the hereditary character of high productivity of S. pristinaespiralis 12–55 is stable. The pristinamycin production of S. pristinaespiralis 12–55 in a 15-l fermentor could reach 3010 u/ml after a 56 h batch fermentation. 相似文献
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《Molecular & general genetics : MGG》1997,256(6):620-627
The het-e gene of the filamentous fungus Podospora anserina is involved in vegetative incompatibility. Co-expression of antagonistic alleles of the unlinked loci het-e and het-c triggers a cell death reaction that prevents the formation of viable heterokaryons between strains that contain incompatible
combinations of het-c and het-e alleles. The het-e1
A gene encodes a polypeptide that contains a putative GTP-binding site and WD40 repeats. The role of these two domains in the
reactivity of the HET-E protein in incompatibility was analyzed. An in vitro assay confirmed that the first domain is functional
and can bind GTP and not ATP, suggesting that GTP-binding is essential for triggering the incompatibility reaction. The relationship
between the number of WD40 repeats and the reactivity of the protein in incompatibility was investigated by estimating this
number in different wild-type and mutant het-e alleles. It was deduced that reactive alleles contain a minimal number of ten WD40 repeats. These results demonstrate that
the reactivity of the HET-E protein depends on two functional elements, a GTP-binding domain and several WD40 repeats. These
motifs are present in separate polypeptides in trimeric G proteins, suggesting that HET-E polypeptides are also involved in
signal transduction. Disruption of the het-e locus does not impair the phenotype of strains but DNA hybridization analyses revealed that het-e may belong to a multigenic family.
Received: 20 January 1997 / Accepted: 8 June 1997 相似文献
11.
J. Ramón De Lucas Susana Valenciano A. I. Domínguez Geoffrey Turner F. Laborda 《Archives of microbiology》1997,168(6):504-512
Conidia of Aspergillus nidulans were mutagenized with ultraviolet light and were incubated on a special selective medium containing the catalase inhibitor
3-amino-1,2,4-triazole. From approximately 5 × 107 viable UV-irradiated conidia tested, 423 stable mutants resistant to 3-amino-1,2,4-triazole were recovered, of which 40
were unable to grow on minimal medium with oleic acid as the sole carbon source. These oleate-nonutilizing (Ole–) mutants did not grow on medium with carbon sources requiring functional peroxisomes (oleate, butyrate, acetate, or ethanol),
but grew well on medium with carbon sources supposedly not requiring such organelles (glucose, glycerol, l-glutamate, or l-proline). The Ole– mutants carried mutations in one of five nuclear genes affecting acetate utilization: acuJ, acuH, acuE, acuL, and perA. The perA21 strain (DL21) carried a mutation in a gene that is not allelic with any of the known acu loci and displayed a phenotype resembling that described in the Pim– (peroxisome import defective) mutants of Hansenula polymorpha. Hyphae of the perA21 mutant contained a few small peroxisomes with the bulk of peroxisomal enzymes remaining in the 20,000 ×g supernatant, but produced wild-type levels of penicillin.
Received: 16 April 1997 / Accepted: 26 July 1997 相似文献
12.
Reijngoud Jos Arentshorst Mark Ruijmbeek Claudine Reid Ian Alazi Ebru Demirci Punt Peter J. Tsang Adrian Ram Arthur F. J. 《Biotechnology letters》2021,43(7):1323-1336
13.
The best studied role of ubiquitination is to mark proteins for destruction by the proteasome but, in addition, it has recently been shown to promote macromolecular assembly and function, and alter protein function, thus playing a regulatory role distinct from protein degradation. Deubiquinating enzymes, the ubiquitin-processing proteases (ubps) and the ubiquitin carboxy-terminal hydrolases (uchs), remove ubiquitin from ubiquitinated substrates. We show here that the creB gene involved in carbon catabolite repression in Aspergillus nidulans encodes a functional member of the novel subfamily of the ubp family defined by the human homologue UBH1, thus implicating ubiquitination in the process of carbon catabolite repression. Members of the novel subfamily of ubps that include CreB are widespread amongst eukaryotes, with homologues present in mammals, nematodes, Drosophila and Arabidopsis, but mutations in the genes have only been identified in A. nidulans. From phenotypes of the A. nidulans mutants it is probable that this subfamily is involved in complex regulatory pathways. Mutations in the gene encoding the WD40 repeat protein CreC result in an identical phenotype, implicating both genes in this pathway. 相似文献
14.
Sanghun Lee Junhee Lee Kyung-Hee Paek Suk-Yoon Kwon Hye Sun Cho Shin Je Kim Jeong Mee Park 《Plant biotechnology reports》2010,4(2):165-172
Genes that are expressed early in specific response to high salinity conditions were isolated from rapeseed plant (Brassica napus L.) using an mRNA differential display method. Five PCR fragments (DD1–5) were isolated that were induced by, but showed
different response kinetics to, 200 mM NaCl. Nucleotide sequence analysis and homology search revealed that the deduced amino
sequences of three of the five cDNA fragments showed considerable similarity to those of β-mannosidase (DD1), tomato Pti-6
proteins (DD5), and the tobacco harpin-induced protein hin1 (DD4), respectively. In contrast, the remaining clones, DD3 and
DD2, did not correspond to any substantial existing annotation. Using the DD3 fragment as a probe, we isolated a full-length
cDNA clone from the cDNA library, which we termed BnSWD1 (Brassica napus salt responsive WD40 1). The predicted amino-acid sequence of BnSWD1 contains eight WD40 repeats and is conserved in all
eukaryotes. Notably, the BnSWD1 gene is expressed at high levels under salt-stress conditions. Furthermore, we found that BnSWD1 was upregulated after treatment with abscisic acid, salicylic acid, and methyl jasmonate. Our study suggests that BnSWD1,
which is a novel WD40 repeat-containing protein, has a function in salt-stress responses in plants, possibly via abscisic
acid-dependent and/or -independent signaling pathways. 相似文献
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We have studied the effect of disrupting catabolite (de)repression genes SNF1, SNF4, and MIG1 on the cell cycle behavior of the CEN.PK122 wild type (WT) strain of Saccharomyces cerevisiae by flow cytometry in glucose-limited chemostat cultures or batch growth in the presence of different carbon sources. Through
a combination of flow cytometry of propidium iodide–stained cells and mathematical modeling we showed that the deletion of
the SNF4 gene provoked a decrease in the length of G1 with respect to the WT strain along with a smaller difference in the cell cycle
length of parent and daughter cells. snf1 and mig1 mutants exhibited slightly shorter G1 respect to the WT. Additionally, in the mig1 mutant the cell cycle length of parent and daughter cells was slightly altered. The results obtained are in agreement with
the view that the SNF4 gene is involved in the regulation of cell cycle in yeast.
Received: 28 May 1998 / Accepted: 20 July 1998 相似文献
17.
Sporulation in Bacillus subtilis can be triggered by carbon catabolite limitation. Conversely, carbon source excess can repress the production of extracellular enzymes, motility, and sporulation. Recent studies have implicated a pH-sensing mechanism, involving AbrB, the TCA cycle, Spo0K, and ÏH in controlling the catabolite repression of sporulation gene expression. In an accompanying paper, we demonstrate that the AbrB-dependent pH-sensing mechanism may not be the only means by which carbon catabolites affect sporulation. In the studies reported here, we have examined the molecular basis underlying the catabolite repression phenotype of mutations in the hpr (scoC), rpoD (crsA47), and spo0A (rvtA11) loci. Loss of function mutations in hpr (scoC) restored sporulation gene expression and sporulation in the presence of excess catabolite(s), suggesting that Hpr (ScoC) has a pivotal role in mediating catabolite repression. Moreover, hpr gene expression increased substantially in the presence of excess catabolite(s), further supporting the involvement of Hpr (ScoC) in the carbon catabolite response system. We suggest that alterations in the phosphorelay response to catabolites may be one mechanism by which catabolite-resistant mutants such as crsA and rvtA are able to sporulate in the presence of excess glucoseReceived: 12 November 2002 / Accepted: 13 December 2002 相似文献
18.
New genes involved in carbon catabolite repression and derepression in the yeast Saccharomyces cerevisiae. 总被引:21,自引:3,他引:18
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A mutation causing resistance to carbon catabolite repression in gene HEX2, mutant allele hex2-3, causes an extreme sensitivity to maltose when in combination with the genes necessary for maltose metabolism. This provided a convenient system for the selective isolation of mutations in genes specifically required for maltose metabolism and other genes involved in general carbon catabolite repression. In addition to reversion of the hex2-3 allele, mutations in three other genes were detected. These genes were called CAT1, CAT3, and MUR1 and in a mutated form abolished maltose inhibition caused by mutant allele hex2-3. Mutant alleles cat1 and cat3 also restored normal repression in the presence of the hex2-3 allele. Segregants having only mutant alleles cat1 or cat3 were obtained by tetrad analysis. These segregants could not grow on nonfermentable carbon sources. Mutant alleles of gene CAT1 were allelic to a mutant allele cat1-1 previously isolated (Zimmermann et al., Mol. Gen. Genet. 151:95-103). Such mutants prevented derepression not only of the maltose catabolizing system, the selected property, but also of glyoxylate shunt and gluconeogenic enzymes. However, respiratory activities and invertase formation were not affected under derepressing conditions. cat3 mutants had the same phenotypic properties as cat1 mutants. This showed that carbon metabolism in yeast cells is under a very complex and ramified control of repressing and derepressing genes, which are interdependent. 相似文献
19.
Two genes encoding sucrose synthase (SUS), namely SUS2 (At5g49190) and SUS3 (At4g02280), are strongly and differentially expressed in Arabidopsis seed. Detailed biochemical analysis was carried out
in developing seeds 9–21 days after flowering (DAF) of wild type and two knockouts. SUS2 and SUS3 are not redundant genes since single knockouts show a phenotype in developing seeds. The mutants had 30–50% less SUS activity
and therefore accumulated 40% more sucrose and 50% less fructose at 15 DAF. This did not affect the hexose-P pool, but led
to 30–70% less starch in embryo and seed coat. Lipids were 55% higher in both mutants at 9–15 DAF. It seems that sucrolysis
via SUS is not required for oil or protein synthesis but rather for channeling carbon toward ADP-glucose and starch in seeds.
Metabolite profiling with GC–TOF revealed specific downstream changes in primary metabolism as a consequence of signaling
or regulatory fine-tuning. While sucrose increased, hexoses and specific amino acids decreased reciprocally. There was a developmental
shift regarding an earlier timing of dry weight accumulation, germinative maturity, oil deposition, sugar levels, transient
starch buildup, and protein storage. Nevertheless, final seed size and composition were unaltered due to an earlier cessation
of growth, thus giving rise to an apparent silent phenotype of mature mutant seeds. We conclude that SUS is important for
metabolite homeostasis and timing of seed development, and propose that an altered sucrose/hexose ratio can modify carbon
partitioning and the pattern of storage compounds in Arabidopsis. 相似文献
20.
Nitrogen metabolite repression in Aspergillus nidulans 总被引:47,自引:0,他引:47
Summary In Aspergillus nidulans, mutations, designated areAr, can result in the inability to utilise a wide variety of nitrogen sources including amino acids, purines, amides, nitrate, and nitrite, whilst not affecting growth on ammonium. Other allelic areA mutations, designated areAd, lead to derepression of one or more activities which are ammonium repressible in wild type (areA+) strains, whilst not affecting their inducibility. Various areA mutations exhibit a wide variety of phenotypes: areAr alleles can be temperature sensitive on some nitrogen sources while not on others, and different alleles can be temperature sensitive for utilisation of different nitrogen sources. areAd alleles can be derepressed for one ammonium-repressible activity, be normally repressible for another, and lead to abnormally low levels for a third. Once again each areAd allele has its own highly specific phenotype. The inability of areAr strains to utilise most nitrogen sources is paralleled by low activities of certain ammonium-repressible enzymes. areAr mutations appear to be epistatic to some but not all regulatory mutations leading to constitutive synthesis of inducible enzymes and also epistatic to gdhA mutations which lead both to loss of NADP-linked glutamate dehydrogenase and to derepression of ammonium-repressible activities.
areAr mutations do not interfere with repair of a large number of auxotrophies in double mutants. Furthermore, although areAr mutations prevent utilisation of L-arginine, L-ornithine, and L--amino-n-butyrate as nitrogen sources, they do not prevent the metabolism of these compounds necessary for repairing auxotrophies for proline and isoleucine in the appropriate double mutants. Utilisation of acetamide and most amino acids as carbon or carbon and nitrogen sources is unaffected by areAr mutations, and areAr strains are able to utilise acetamide and L-proline (but not other amino acids) as nitrogen sources in the presence of non-catabolite-repressing carbon sources such as L-arabinose, glycerol, melibiose, and lactose. Suppressor mutations, designated creAd, probably leading to loss of carbon catabolite repression, allow utilisation of acetamide and proline as nitrogen sources in areAr double mutants in the presence of carbon catabolite-repressing carbon sources. creAd mutations allow ethanol to serve as a source of acetate for pyruvate dehydrogenaseless (pdhA) strains in the presence of carbon catabolite-repressing carbon sources, whereas pdhA single mutants respond to ethanol as sole carbon source only in the presence of non-carbon catabolite-repressing carbon sources. Specific suppressor mutations, designated amd
d and prn
d, allow utilisation of acetamide or proline, respectively, in areAr double mutants.The areA locus can be interpreted as specifying a protein which is capable of (and in most cases essential for) allowing the synthesis of a number of enzymes of nitrogen metabolism but which cannot function in the presence of ammonium (i.e., as specifying a positive regulatory element which mediates ammonium repression) although the possibility that the areA product also plays a negative regulatory role cannot at present be ruled out. 相似文献