Molecular Mechanism of Citrate Efflux by the Mitochondrial Citrate Transporter CT in Filamentous Fungus Mucor circinelloides WJ11

Frontiers in Microbiology

Junhuan Yang¹  Wu Yang²  Hassan Mohamed²  Huirong Fan²  Yusuf Nazir²  Aabid Manzoor Shah³  Xiuzhen Gao⁴  Shiqi Dong⁵  Yuanda Song⁵ 

[1] Peking Union Medical College, Tianjin, China;Colin Ratledge Center for Microbial Lipids, School of Agriculture Engineering and Food Science, Shandong University of Technology, Zibo, China;Department of Botany and Microbiology, Faculty of Science, Al-Azhar University, Assiut, Egypt;Department of Food Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi, Malaysia;;Tianjin Key Laboratory of Radiation Medicine and Molecular Nuclear Medicine, Institute of Radiation Medicine, Chinese Academy of Medical Sciences &

关键词: Mucor circinelloides;    citrate carrier;    mitochondrial citrate transporter;    citrate efflux;    transport activity;   

DOI  :  10.3389/fmicb.2021.673881

来源: DOAJ

【 摘 要 】

The mitochondrial citrate transporter (MCT) plays an important role in citrate efflux from the mitochondria in eukaryotes, and hence provides a direct correlation between carbohydrate metabolism and lipid synthesis. Our previous studies on transporters confirmed the presence of two MCTs (TCT and CT) in oleaginous Mucor circinelloides WJ11 associated with high lipid accumulation. However, the molecular mechanism of citrate efflux from the mitochondria by MCT in M. circinelloides is still unclear. To study the citrate transport mechanism of CT, the citrate transporter gene was expressed in Escherichia coli, and its product was purified. The citrate transport activity of the protein was studied in CT reconstituted liposomes. Our results showed high efficiency of CT for [14C] citrate/citrate exchange with Km 0.01 mM at 25°C. Besides citrate, other molecules such as oxaloacetate, malate, fumarate, succinate aconitate, oxoadipate, isocitrate, and glutamate also promote citrate transport. In addition, the ct overexpression and knockout plasmids were constructed and transferred into M. circinelloides WJ11, and the mitochondria were isolated, and the transport activity was studied. Our findings showed that in the presence of 10 mM malate, the mitochondria of ct-overexpressing transformant showed 51% increase in the efflux rate of [14C] citrate, whereas the mitochondria of the ct-knockout transformant showed 18% decrease in citrate efflux compared to the mitochondria of wild-type WJ11. This study provided the first mechanistic evidence of citrate efflux from the mitochondria by citrate transporter in oleaginous filamentous fungus M. circinelloides, which is associated with high lipid accumulation.

【 授权许可】

Unknown