@article{mbs:/content/journal/micro/10.1099/13500872-145-8-1911, author = "Wynn, James P. and Hamid, Aidil bin Abdul and Ratledge, Colin", title = "The role of malic enzyme in the regulation of lipid accumulation in filamentous fungi", journal= "Microbiology", year = "1999", volume = "145", number = "8", pages = "1911-1917", doi = "https://doi.org/10.1099/13500872-145-8-1911", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/13500872-145-8-1911", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", keywords = "Mortierella alpina", keywords = "malic enzyme", keywords = "lipids", keywords = "Mucor circinelloides", 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 NH+ 4 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.", }