Inhibition of Chitin Metabolism

Gooday, Graham W.

doi:10.1007/978-3-642-74215-6_5

Cited by 37 publications

(11 citation statements)

References 109 publications

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“…Moreover, chitin synthesis in vivo was characterized in regenerating protoplasts and chitin synthase activity of cell-free extracts from hyphae was demonstrated (Bulone el al., 1992). The crude enzyme preparation exhibited properties such as zymogenicity, Mg2+ stimulation, apparent Km for UDP-GlcNAc and inhibition with polyoxin D similar to those reported for other fungi (Gooday, 1990).…”

Section: Introductionsupporting

confidence: 66%

“…This large difference in specific activity between membrane-bound and solubilized enzyme may have been related to the accessibility of the substrate to the enzyme. When mixed-membrane fractions were permeabilized with digitonin, the specific activity reached 1-7 nmol mg-' min-I, which was in the range of activities observed with typical chitinous fungi (Gooday, 1990 ;Gay, 1991).…”

Section: Discussionmentioning

confidence: 58%

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Synthesis in vitro of crystalline chitin by a solubilized enzyme from the cellulosic fungus Saprolegnia monoica

Gay

Chanzy

Bulone

et al. 1993

Journal of General Microbiology

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Enriched preparations of chitin synthase were obtained from cell homogenates from Supvolegnia monoica. Chitin synthase was solubilized from a mixed membrane fraction by two successive digitonin treatments. Glycerol gradient centrifugation of the solubilized proteins separated the chitin synthase activity from the majority of proteins and from 8-1,3 and p-1,4 glucan synthases. The properties of chitin synthase from this Oomycete fungus are similar to those reported for the enzymes of ehitinous fungi. The solubilized enzyme catalysed the synthesis in vitvo of spindle-like crystals of chitin. Biophysical analysis (by electron and X-ray diffractornetry and infrared spectroscopy) demonstrated that the polymer synthesized in vitro was a-chitin. These results and those previously reported demonstrate unambiguously that chitin synthase and chitin are normal components of the cell wall of the cellulosic fungus S. munoica.

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Section: Introductionsupporting

confidence: 66%

Section: Discussionmentioning

confidence: 58%

Synthesis in vitro of crystalline chitin by a solubilized enzyme from the cellulosic fungus Saprolegnia monoica

Gay

Chanzy

Bulone

et al. 1993

Journal of General Microbiology

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“…All chitin synthase enzymes are presumed to carry out the same reaction that results in the addition of N-acetyl glucosamine to the extending oligosaccharide chain. The monomer N-acetylglucosamine acts as an activator of the enzyme, which is inhibited by the reaction product UDP [12]. The enzyme is usually assayed in microsomal fractions of disrupted cells, and total activity is increased by the addition of cation activators that can be Mg 2 ‡ , Mn 2 ‡ or Co 2 ‡ for different enzymes.…”

Section: Introductionmentioning

confidence: 99%

Chitin synthesis in human pathogenic fungi

2001

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In recent years it has become evident that the structural polysaccharide chitin is synthesized from a family of enzymes encoded by multiple CHS chitin synthase genes, and regulated by an array of ancillary gene products that influence CHS activation and localization. Considerable attention has therefore been given to elucidating the function of specific CHS gene products in individual fungi. In those fungi in which individual CHS genes have been deleted systematically, there is little evidence for redundancy of function in family members. Chs enzymes are now known that participate in lateral wall biosynthesis, septum synthesis and spore formation but the phenotype of some CHS gene mutations is subtle, and so the role of the corresponding isoenzymes remains obscure. Nonetheless, it has become clear that certain members of the CHS gene families of fungi are more important for growth, integrity and viability than others, and this knowledge has already led to the design of new classes of antifungal agents that are targeted against key enzyme activities. Future work in this area will help define how individual Chs enzymes are targeted to specific regions of the cell wall and at specific times of the cell cycle, and should facilitate the rational development of novel and highly specific antifungal agents.

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“…In both yeasts and filamentous fungi, chitin contributes significantly to the mechanical strength of the cell wall. When chitin synthesis is affected, growing hyphae tend to lyse and form pronounced bulges unless the osmolarity of the medium is increased (Benitez et al, 1976;Gooday, 1990;Bago et al, 1996;Specht et al, 1996;Aufauvre-Brown et al, 1997). Genes encoding chitin synthases have been isolated from many yeasts and filamentous fungi and have been classified into six classes according to their sequence similarity (reviewed by Roncero, 2002).…”

Section: Introductionmentioning

confidence: 99%

The cell wall stress response in Aspergillus niger involves increased expression of the glutamine : fructose-6-phosphate amidotransferase-encoding gene (gfaA) and increased deposition of chitin in the cell wall

Ram

2004

Microbiology

121

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Perturbation of cell wall synthesis in Saccharomyces cerevisiae, either by mutations in cell wall synthesis-related genes or by adding compounds that interfere with normal cell wall assembly, triggers a compensatory response to ensure cell wall integrity. This response includes an increase in chitin levels in the cell wall. Here it is shown that Aspergillus niger also responds to cell wall stress by increasing chitin levels. The increased chitin level in the cell wall was accompanied by increased transcription of gfaA, encoding the glutamine : fructose-6-phosphate amidotransferase enzyme, which is responsible for the first and a rate-limiting step in chitin synthesis. Cloning and disruption of the gfaA gene in A. niger showed that it was an essential gene, but that addition of glucosamine to the growth medium could rescue the deletion strain. When the plant-pathogenic fungus Fusarium oxysporum and food spoilage fungus Penicillium chrysogenum were subjected to cell wall stress, the transcript level of their gfa gene increased as well. These observations suggest that cell wall stress in fungi may generally lead to activation of the chitin biosynthetic pathway.

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Inhibition of Chitin Metabolism

Cited by 37 publications

References 109 publications

Synthesis in vitro of crystalline chitin by a solubilized enzyme from the cellulosic fungus Saprolegnia monoica

Synthesis in vitro of crystalline chitin by a solubilized enzyme from the cellulosic fungus Saprolegnia monoica

Chitin synthesis in human pathogenic fungi

The cell wall stress response in Aspergillus niger involves increased expression of the glutamine : fructose-6-phosphate amidotransferase-encoding gene (gfaA) and increased deposition of chitin in the cell wall

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