Isolation of mutants deficient in acetyl-CoA synthetase and a possible regulator of acetate induction in Aspergillus niger

Sealy-Lewis, Heather M.; Fairhurst, Valerie

doi:10.1099/00221287-144-7-1895

Cited by 13 publications

(8 citation statements)

References 26 publications

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“…In Rhodobacter sphaeroides, propionyl-CoA was found to inhibit pyruvate dehydrogenase (19), and in Escherichia coli, propionyl-CoA is a competitive inhibitor of citrate synthase (20). Support for the idea that propionyl-CoA is a problem for the cell was also obtained in Aspergillus niger, where experiments blocking propionyl-CoA formation relieved propionate sensitivity (21). However, recent experiments suggest that the inhibitory effects of propionate in A. niger may be caused by 2-methylcitrate accumulation (22).…”

mentioning

confidence: 52%

Studies of Propionate Toxicity in Salmonella enterica Identify 2-Methylcitrate as a Potent Inhibitor of Cell Growth

Horswill¹,

Dudding

Escalante‐Semerena

2001

Journal of Biological Chemistry

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Salmonella enterica serovar Typhimurium LT2 showed increased sensitivity to propionate when the 2-methylcitric acid cycle was blocked. A derivative of a prpC mutant (which lacked 2-methylcitrate synthase activity) resistant to propionate was isolated, and the mutation responsible for the newly acquired resistance to propionate was mapped to the citrate synthase (gltA) gene. These results suggested that citrate synthase activity was the source of the increased sensitivity to propionate observed in the absence of the 2-methylcitric acid cycle. DNA sequencing of the wild-type and mutant gltA alleles revealed that the ATG start codon of the wild-type gene was converted to the rare GTG start codon in the revertant strain. This result suggested that lower levels of this enzyme were present in the mutant. Consistent with this change, cell-free extracts of the propionate-resistant strain contained 12-fold less citrate synthase activity. This was interpreted to mean that, in the wild-type strain, high levels of citrate synthase activity were the source of a toxic metabolite. In vitro experiments performed with homogeneous citrate synthase enzyme indicated that this enzyme was capable of synthesizing 2-methylcitrate from propionyl-CoA and oxaloacetate. This result lent further support to the in vivo data, which suggested that citrate synthase was the source of a toxic metabolite.

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mentioning

confidence: 52%

Studies of Propionate Toxicity in Salmonella enterica Identify 2-Methylcitrate as a Potent Inhibitor of Cell Growth

Horswill¹,

Dudding

Escalante‐Semerena

2001

Journal of Biological Chemistry

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“…It had previously been found that disruptants of acuB are able to grow on propionate but not on acetate as a sole carbon source (23,25). Moreover, it was observed that propionate interferes with sporulation and growth of strains able to use acetate (25).…”

Section: Resultsmentioning

confidence: 99%

“…Moreover, it was observed that propionate interferes with sporulation and growth of strains able to use acetate (25). Accordingly, since acuB-positive strains fail to sporulate on propionate medium, acuB⌬ strains can be identified simply as strains that sporulate on this medium.…”

Section: Resultsmentioning

confidence: 99%

Transient Marker System for Iterative Gene Targeting of a Prototrophic Fungus

Nielsen

Jongh

Meijer

et al. 2007

Appl Environ Microbiol

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Auxotrophic microorganisms are often used for genetic engineering, because their biosynthetic deficiency can be complemented by the transforming DNA and allows selection for transformants that have become prototrophic. However, when complementation is obtained by ectopic expression this may lead to unpredictable side effects on the phenotype and, consequently, misinterpretation of experimental data. There are various ways to overcome the problem of auxotrophy, but the most reliable is to restore the function of the defective biosynthetic gene at the native genomic locus. This can be done by either sexual crossing or further genetic engineering. For fungal species lacking a perfect state or situations in which gene targeting is generally cumbersome we have developed a concept that allows transient disruption of pyrG. When the gene is in the disrupted state, multiple rounds of gene targeting can be performed with the strain. Once the desired genome engineering is completed, pyrG function can be rapidly returned to wild type by a simple selection scheme.

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“…In A. nidulans, A. niger and Coprinus cinereus conventional mutagenesis coupled with selection for either fluoroacetate or proprionate resistance resulted in the isolation of a number of acetate non-utilising mutants (Apirion 1965;Armitt et al 1976;Vousden and Casselton 1983;Sealy-Lewis 1994;Sealy-Lewis and Fairhurst 1998). Common classes amongst these mutants are the facB-like mutants, which typically show poor induction of a series of enzymes required for acetate utilisation (Hynes 1977;Maconochie et al 1992;Sealy-Lewis and Fairhurst 1998).…”

Section: Discussionmentioning

confidence: 98%

“…Common classes amongst these mutants are the facB-like mutants, which typically show poor induction of a series of enzymes required for acetate utilisation (Hynes 1977;Maconochie et al 1992;Sealy-Lewis and Fairhurst 1998). The facB gene product has been established as a positively acting regulatory factor required for the induction of the genes of the glyoxylate cycle, as well as the metabolite-mobilising enzymes acetyl-CoA synthetase (facA) and acetamidase (amdS) (Katz and Hynes 1989;Todd et al 1998).…”

Section: Discussionmentioning

confidence: 99%

A regulator gene for acetate utilisation from Neurospora crassa

Bibbins

et al. 2002

Mol Gen Genomics

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The Neurospora crassa homologue of the Aspergillus nidulans regulatory gene facB has been cloned. The gene encodes a putative transcriptional activator of 865 amino acids that contains a DNA-binding domain with a Zn(II)(2)Cys(6) binuclear cluster, a linker region and a leucine zipper-like heptad repeat. Two internal amino acid sequences are identical to peptide sequences determined from proteolytic fragments of a DNA-binding protein complex specific for genes involved in acetate utilisation and expressed in acetate-induced mycelia of N. crassa. Recombinant expression of the predicted DNA-binding domain demonstrates that it is capable of independent recognition of a subset of the promoter sequences that bind the protein complex from N. crassa. A duplication-induced mutation in the corresponding gene results in an acetate non-utilising phenotype that is characterised by inefficient induction of the enzymes required for acetate utilisation. The new gene does not fall into any existing complementation group and has been designated acu-15.

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Isolation of mutants deficient in acetyl-CoA synthetase and a possible regulator of acetate induction in Aspergillus niger

Abstract: Acetate-non-utilizing mutants in

Cited by 13 publications

References 26 publications

Studies of Propionate Toxicity in Salmonella enterica Identify 2-Methylcitrate as a Potent Inhibitor of Cell Growth

Studies of Propionate Toxicity in Salmonella enterica Identify 2-Methylcitrate as a Potent Inhibitor of Cell Growth

Transient Marker System for Iterative Gene Targeting of a Prototrophic Fungus

A regulator gene for acetate utilisation from Neurospora crassa

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