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Polyamines in growth and dimorphism of Paracoccidioides brasiliensis
G San-Blas1, F San-Blas, F Sorais
1Instituto Venezolano de Investigaciones Científicas (IVIC), Centro de Microbiología y Biología Celular, Apartado 21827, Caracas 1020A, Venezuela.
Abstract:
Putrescine and spermidine were the only polyamines found in Paracoccidioides brasiliensis, a dimorphic fungus pathogenic for humans. Free polyamines (putrescine > spermidine) increased during the first 24 h of yeast growth, with a second peak at 42 h, and also during the first 12 h of mycelium-to-yeast transition (spermidine > putrescine). Conjugated and bound polyamines were also quantified. 1, 4-Diamino-2-butanone decreased free putrescine and spermidine accumulation by inhibiting the activity of ornithine decarboxylase. The increase in free polyamines corresponds to bud emergence in yeast growth and to the mycelium-to-yeast transition of P. brasiliensis.
Insights
Polyamines like putrescine and spermidine increase during Paracoccidioides brasiliensis growth and the crucial yeast transition. Inhibiting ornithine decarboxylase affects these vital compounds.
Area of Science:
- Medical Mycology
- Biochemistry
- Molecular Biology
Background:
- Paracoccidioides brasiliensis is a human pathogenic fungus.
- Polyamines are crucial for cell growth and differentiation.
- Understanding polyamine metabolism in P. brasiliensis is key to its pathogenesis.
Purpose of the Study:
- To investigate the role of polyamines (putrescine and spermidine) in the growth and morphological transition of Paracoccidioides brasiliensis.
- To quantify free, conjugated, and bound polyamines during different growth phases.
- To assess the effect of ornithine decarboxylase inhibition on polyamine levels.
Main Methods:
- Quantification of polyamines (putrescine, spermidine) during yeast growth and mycelium-to-yeast transition.
- Analysis of free, conjugated, and bound polyamine fractions.
- Treatment with 1,4-Diamino-2-butanone to inhibit ornithine decarboxylase.
Main Results:
- Putrescine and spermidine were the predominant polyamines in P. brasiliensis.
- Free polyamine levels peaked during early yeast growth and mycelium-to-yeast transition.
- 1,4-Diamino-2-butanone significantly reduced free putrescine and spermidine by inhibiting ornithine decarboxylase.
Conclusions:
- Increased free polyamines correlate with key developmental stages in P. brasiliensis, including bud emergence and the dimorphic transition.
- Ornithine decarboxylase is a critical enzyme for polyamine biosynthesis in this fungus.
- Polyamines are essential for the growth and pathogenicity of Paracoccidioides brasiliensis.