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

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)...

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Main Authors: Wu Yang, Shiqi Dong, Junhuan Yang, Hassan Mohamed, Aabid Manzoor Shah, Yusuf Nazir, Xiuzhen Gao, Huirong Fan, Yuanda Song
Format: Article
Language:English
Published: Frontiers Media S.A. 2021-05-01
Series:Frontiers in Microbiology
Subjects:
Online Access:https://www.frontiersin.org/articles/10.3389/fmicb.2021.673881/full
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author Wu Yang
Shiqi Dong
Junhuan Yang
Hassan Mohamed
Hassan Mohamed
Aabid Manzoor Shah
Yusuf Nazir
Yusuf Nazir
Xiuzhen Gao
Huirong Fan
Yuanda Song
author_facet Wu Yang
Shiqi Dong
Junhuan Yang
Hassan Mohamed
Hassan Mohamed
Aabid Manzoor Shah
Yusuf Nazir
Yusuf Nazir
Xiuzhen Gao
Huirong Fan
Yuanda Song
author_sort Wu Yang
collection DOAJ
description 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.
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spelling doaj.art-a66cc77552b24802a4fecef8698d71792022-12-21T19:57:54ZengFrontiers Media S.A.Frontiers in Microbiology1664-302X2021-05-011210.3389/fmicb.2021.673881673881Molecular Mechanism of Citrate Efflux by the Mitochondrial Citrate Transporter CT in Filamentous Fungus Mucor circinelloides WJ11Wu Yang0Shiqi Dong1Junhuan Yang2Hassan Mohamed3Hassan Mohamed4Aabid Manzoor Shah5Yusuf Nazir6Yusuf Nazir7Xiuzhen Gao8Huirong Fan9Yuanda Song10Colin Ratledge Center for Microbial Lipids, School of Agriculture Engineering and Food Science, Shandong University of Technology, Zibo, ChinaTianjin Key Laboratory of Radiation Medicine and Molecular Nuclear Medicine, Institute of Radiation Medicine, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin, ChinaColin Ratledge Center for Microbial Lipids, School of Agriculture Engineering and Food Science, Shandong University of Technology, Zibo, ChinaColin Ratledge Center for Microbial Lipids, School of Agriculture Engineering and Food Science, Shandong University of Technology, Zibo, ChinaDepartment of Botany and Microbiology, Faculty of Science, Al-Azhar University, Assiut, EgyptColin Ratledge Center for Microbial Lipids, School of Agriculture Engineering and Food Science, Shandong University of Technology, Zibo, ChinaColin Ratledge Center for Microbial Lipids, School of Agriculture Engineering and Food Science, Shandong University of Technology, Zibo, ChinaDepartment of Food Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi, MalaysiaColin Ratledge Center for Microbial Lipids, School of Agriculture Engineering and Food Science, Shandong University of Technology, Zibo, ChinaTianjin Key Laboratory of Radiation Medicine and Molecular Nuclear Medicine, Institute of Radiation Medicine, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin, ChinaColin Ratledge Center for Microbial Lipids, School of Agriculture Engineering and Food Science, Shandong University of Technology, Zibo, ChinaThe 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.https://www.frontiersin.org/articles/10.3389/fmicb.2021.673881/fullMucor circinelloidescitrate carriermitochondrial citrate transportercitrate effluxtransport activity
spellingShingle Wu Yang
Shiqi Dong
Junhuan Yang
Hassan Mohamed
Hassan Mohamed
Aabid Manzoor Shah
Yusuf Nazir
Yusuf Nazir
Xiuzhen Gao
Huirong Fan
Yuanda Song
Molecular Mechanism of Citrate Efflux by the Mitochondrial Citrate Transporter CT in Filamentous Fungus Mucor circinelloides WJ11
Frontiers in Microbiology
Mucor circinelloides
citrate carrier
mitochondrial citrate transporter
citrate efflux
transport activity
title Molecular Mechanism of Citrate Efflux by the Mitochondrial Citrate Transporter CT in Filamentous Fungus Mucor circinelloides WJ11
title_full Molecular Mechanism of Citrate Efflux by the Mitochondrial Citrate Transporter CT in Filamentous Fungus Mucor circinelloides WJ11
title_fullStr Molecular Mechanism of Citrate Efflux by the Mitochondrial Citrate Transporter CT in Filamentous Fungus Mucor circinelloides WJ11
title_full_unstemmed Molecular Mechanism of Citrate Efflux by the Mitochondrial Citrate Transporter CT in Filamentous Fungus Mucor circinelloides WJ11
title_short Molecular Mechanism of Citrate Efflux by the Mitochondrial Citrate Transporter CT in Filamentous Fungus Mucor circinelloides WJ11
title_sort molecular mechanism of citrate efflux by the mitochondrial citrate transporter ct in filamentous fungus mucor circinelloides wj11
topic Mucor circinelloides
citrate carrier
mitochondrial citrate transporter
citrate efflux
transport activity
url https://www.frontiersin.org/articles/10.3389/fmicb.2021.673881/full
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