Oxidation of carbon sources via the tricarboxylic acid cycle during calcium-induced conidation ofPenicillium notatum
✍ Scribed by D. Pitt; M. J. Mosley
- Book ID
- 104769620
- Publisher
- Springer Netherlands
- Year
- 1986
- Tongue
- English
- Weight
- 903 KB
- Volume
- 52
- Category
- Article
- ISSN
- 0003-6072
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✦ Synopsis
The TCA cycle was examined during Ca2+-induced conidiation in Penicillium notatum over the 12-h period after addition of Ca 2+ to vegetative cultures. Conidiation was independent of Ca 2 + when certain intermediates and derivatives of the TCA cycle served as sole carbon sources• Arsenite and malonate augmented the effect of Ca 2+ on conidiation but did not substitute for it. Mitochondria from vegetative cells had low rates of oxidation of TCA cycle intermediates and, with the exception of pyruvate, aconitate and glutamate, these were poorly linked to phosphorylation processes. Calcium ions affected mitochondrial function causing reduced oxidation of oxoglutarate, elimination of pyruvate oxidation and a decline in respiratory control of these substrates with increased oxidation of NADH and NADPH• Radiorespirometric studies and enzyme searches revealed a complete but weakly oxidative TCA cycle in vegetative cells• In Ca 2 +-induced cells oxoglutarate dehydrogenase activity was deleted within 6.5 h of Ca 2 + addition and this was accompanied by establishment of an 'incomplete Krebs cycle'• Calcium-induced conidiation was associated with increased capacity for acetate and glutamate metabolism involving an activated glyoxylate shunt which may be related to enhanced biosynthetic demand. The metabolic basis of the Ca 2+ effect • on conidiation is discussed in connection with previous findings.