The role of malic enzyme in the regulation of lipid accumulation in filamentous fungi

James P. Wynn, Aidil Abdul Hamid, Colin Ratledge

Research output: Contribution to journalArticle

153 Citations (Scopus)

Abstract

The hypothesis is advanced that NADP+-malic enzyme (ME; EC 1.1.1.40) is an important activity in regulating the extent of lipid accumulation in filamentous fungi. In Mucor circinelloides, a fungus capable of accumulating only 25% (w/w, dry wt) lipid, even under the most propitious conditions, ME disappears 15-20 h after nitrogen exhaustion, coincident with the cessation of lipid accumulation. In contrast, ME in Mortierella alpina, a fungus capable of accumulating 50% (w/w, dry wt) lipid, remains active for over 60 h after N-exhaustion during which time lipid accumulation continues. No other enzyme activity studied, including the lipogenic enzymes acetyl-CoA carboxylase, fatty acid synthase, diacyglycerol acyltransferase, ATP:citrate lyase and the NADPH-generating enzymes glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and NADP+:isocitrate dehydrogenase, demonstrated any correlation with the accumulation of storage lipid in either fungus. Full activity of ME is restored in Mr. circinelloides within 4 h by adding NH4 + to the cultures, but this is prevented by adding cycloheximide as an inhibitor of protein synthesis. This suggests that the decrease in ME activity occurs due to down-regulation of the ME gene.

Original languageEnglish
Pages (from-to)1911-1917
Number of pages7
JournalMicrobiology
Volume145
Issue number8
Publication statusPublished - Aug 1999

Fingerprint

Fungi
Lipids
Enzymes
malate dehydrogenase (oxaloacetate-decarboxylating) (NADP+)
Mortierella
ATP Citrate (pro-S)-Lyase
Phosphogluconate Dehydrogenase
Mucor
Acetyl-CoA Carboxylase
Acyltransferases
Fatty Acid Synthases
Protein Synthesis Inhibitors
Glucosephosphate Dehydrogenase
Cycloheximide
NADP
Nitrogen
Down-Regulation
Genes

Keywords

  • Lipids
  • Malic enzyme
  • Mortierella alpina
  • Mucor circinelloides

ASJC Scopus subject areas

  • Microbiology

Cite this

The role of malic enzyme in the regulation of lipid accumulation in filamentous fungi. / Wynn, James P.; Abdul Hamid, Aidil; Ratledge, Colin.

In: Microbiology, Vol. 145, No. 8, 08.1999, p. 1911-1917.

Research output: Contribution to journalArticle

Wynn, James P. ; Abdul Hamid, Aidil ; Ratledge, Colin. / The role of malic enzyme in the regulation of lipid accumulation in filamentous fungi. In: Microbiology. 1999 ; Vol. 145, No. 8. pp. 1911-1917.
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