Biochemical events leading to the diversion of carbon into storage lipids in the oleaginous fungi $Mucor\ circinelloides$ and $Mortierella\ alpina$

James Wynn (1) , Adil Hamid (2) , Yonghua Li-Beisson (3, 1) , Colin Ratledge (1)

1 Department of Biological Sciences [Hull]
2 UKM - Universiti Kebangsaan Malaysia
3 EBMP - Environnement, Bioénergie, Microalgues et Plantes

The biochemical events associated with the onset of lipid accumulation in Mucor circinelloides and Mortierella alpina, under conditions of nitrogenlimited growth, have been elucidated; they differ in key aspects from those described in oleaginous yeasts. The NADM:isocitrate dehydrogenases of Mc. circinelloides and Mort. alpina were not absolutely dependent on AMP for activity. Furthermore, changes in the cellular adenine nucleotide pools and energy charge were different from those reported for oleaginous yeasts. In Mc. circinelloides ATP, ADP and AMP concentrations all decreased by 50% after nitrogen limitation, leading to a constant energy charge at the expense of the size of the total adenylate pool. Pyruvate carboxylase in Mc. circinelloides was cytosolic, having implications for the organization of lipid synthesis in filamentous fungi. As a result of the data obtained, a revised and more concerted mechanism for the initiation of storage lipid accumulation is put forward for filamentous fungi.

Mots clés: AMP deaminase; NAD+ :isocitrate dehydrogenase; lipid accumulation

Domaines: Sciences du Vivant [q-bio]

James Wynn, Adil Hamid, Yonghua Li-Beisson, Colin Ratledge. Biochemical events leading to the diversion of carbon into storage lipids in the oleaginous fungi $Mucor\ circinelloides$ and $Mortierella\ alpina$. Microbiology, 2001, 147 (10), pp.2857-2864. ⟨10.1099/00221287-147-10-2857⟩. ⟨hal-03429848⟩