Deletion of Plasma Membrane Malate Transporters Increased Lipid Accumulation in the Oleaginous Fungus Mucor circinelloides WJ11

Abstract

Malate as an important intermediate metabolite, its subcellular location, and concentration have a significant impact on fungal lipid metabolism. Previous studies showed that the mitochondrial malate transporter plays an important role in lipid accumulation in Mucor circinelloides by manipulating intracellular malate concentration. However, the role of plasma membrane malate transporters in oleaginous fungi remains unexplored. Therefore, in this work, two plasma membrane malate transporters "2oxoglutarate:malate antiporters" (named SoDIT-a and SoDIT-b) of M. circinelloides WJ11 were deleted, and the consequences in growth capacity, lipid accumulation, and metabolism were analyzed. The results showed that deletion of sodit-a or/and sodit-b reduced the extracellular malate, confirming that the products of both genes participate in malate transportation. In parallel, the lipid contents in mutants increased approximately 10−40% higher than that in the control strain, suggesting that the defect in plasma membrane malate transport results in an increase of malate available for lipid biosynthesis. Furthermore, transcriptional analysis showed that the expression levels of multiple key genes involved in the lipid biosynthesis were also increased in the knockout mutants. To the best of our knowledge, this is the first report that demonstrated the association between plasma membrane malate transporters and lipid accumulation in M. circinelloides.

Role of Cytosolic Malic Enzyme in Oleaginicity of High-Lipid-Producing Fungal Strain Mucor circinelloides WJ11

“…Commercially proficient lipid production necessitates the development of recombinant strains that can accumulate elevated amounts of lipids, independent of the environmental fluctuations. So far, several genetic engineering techniques have been employed to boost lipid production via overexpression or the deletion of important genes and transporters such as malate and citrate transporters [ 39 , 40 , 41 , 42 , 43 ], AMP-activated protein kinase [ 44 , 45 ], the pentose phosphate pathway [ 18 , 46 , 47 ], Acyl CoA: Diacylglycerol Acyltransferase [ 48 ], lipases [ 49 , 50 , 51 ], malic enzymes [ 17 , 24 ], and the utilization of lignocellulosic biomasses [ 52 ].…”

Production, Biosynthesis, and Commercial Applications of Fatty Acids From Oleaginous Fungi

“…As an important intermediate metabolite, malate, its subcellular location and concentration have significant effects on fungal lipid metabolism. Yang et al ( 149 ) deleted the two plasma membrane malate transporters “2-oxoglutarate:malate antiporter” (named SoDIT-a and SoDIT-b) of M. circinelloides WJ11 and analyzed their effects on growth ability, lipid accumulation and metabolism. Their results showed that the lipid content of the mutant was increased by ~10–40% compared to the control strain, indicating that defects in plasma membrane malate transport lead to an increase in malate for lipid synthesis.…”

Mucor circinelloides: a model organism for oleaginous fungi and its potential applications in bioactive lipid production

“…It was found that in mt- overexpression and mt -knockout strains, fatty acid content was increased and decreased by 70% and 27%, respectively [ 70 ]. Moreover, knockout of plasma membrane malate transporters in WJ11 strain elevated the lipid content by 10–40% [ 71 ].…”