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Génomique fonctionnelle des champignons pathogènes des plantes, UMR5240 Microbiologie, Adaptation et Pathogénie, Université Lyon 1, CNRS, Bayer CropScience, Université de Lyon, 14 Rue Pierre Baizet, 69263 Lyon Cedex 9, France
Correspondence
Christophe A Bruel
christophe.bruel{at}univ-lyon1.fr
Sulphur and nitrogen catabolic repressions are regulations that have long been recognized in fungi, but whose molecular bases remain largely elusive. This paper shows that catabolic repression of a protease-encoding gene correlates with the modulation of a phosphatidylethanolamine (PE)-specific phospholipase D (PLD) activity in the pathogenic fungus Botrytis cinerea. Our results first demonstrate that the ACP1 gene is subject to sulphur catabolic repression, with sulphate and cysteine inhibiting its expression. Sulphate and cysteine also cause a decrease of the total cellular PLD activity and, reciprocally, the two PLD inhibitors AEBSF [4-(2-aminoethyl)benzenesulphonyl fluoride] and curcumin negatively affect ACP1 expression in vivo. Cysteine moreover inhibits the PE-specific PLD activity in cell extracts. ACP1 is regulated by nitrogen, but here we show that this regulation does not rely on the proximal AREA binding site in its promoter, and that glutamine does not play a particular role in the process. A decrease in the total cellular PLD activity is also observed when the cells are fed ammonia, but this effect is smaller than that produced by sulphur. RNA-interference experiments finally suggest that the enzyme responsible for the PE-specific PLD activity is encoded by a gene that does not belong to the known HKD gene family of PLDs.
Present address: Dartmouth Medical School, Genetics Department, Remsem 7400 Building, Hanover, NH 03755, USA.
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