Biochemical events leading to the diversion of carbon into storage lipids in the oleaginous fungi Mucor circinelloides and Mortierella alpina.
The biochemical events associated with the onset of lipid accumulation in Mucor circinelloides and Mortierella alpina, under conditions of nitrogen-limited growth, have been elucidated; they differ in key aspects from those described in oleaginous yeasts. The NAD+: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.
Wynn
James P
JP
Centre for Advanced Lipid Research, Department of Biological Sciences, University of Hull, Hull HU6 7RX, UK1.
Hamid
Adil A
AA
Department of Microbiology, Universitii Kebangsaan, Malaysia, 43600 Bangi, Salangor Darul Ehsan, Malaysia2.
Li
Yonghua
Y
Centre for Advanced Lipid Research, Department of Biological Sciences, University of Hull, Hull HU6 7RX, UK1.
Ratledge
Colin
C
Centre for Advanced Lipid Research, Department of Biological Sciences, University of Hull, Hull HU6 7RX, UK1.
D000659:AMP Deaminase / Q000378:metabolism; D000227:Adenine Nucleotides / Q000378:metabolism; D002244:Carbon / Q000378:metabolism*; D003470:Culture Media; D007521:Isocitrate Dehydrogenase / Q000378:metabolism; D050356:Lipid Metabolism; D020094:Mortierella / Q000254:growth & development / Q000378:metabolism*; D009089:Mucor / Q000254:growth & development / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism
D000227:Adenine Nucleotides; D003470:Culture Media; D002244:Carbon; D007521:Isocitrate Dehydrogenase; D000659:AMP Deaminase; D009584:Nitrogen