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Characterization of Membrane Transporters by Heterologous Expression in E. coli and Production of Membrane Vesicles
Published on: December 31, 2019
Characterization of an ammonium transporter in the oleaginous alga Chlorella protothecoides
Dong Yan1, Junbiao Dai, Qingyu Wu
1School of Life Sciences, Tsinghua University, Beijing 100084, People's Republic of China.
Abstract:
A suppression subtractive hybridization cDNA library was used to screen the differently expressed (up-regulated) genes in the photosynthesis-fermentation approach (PFA) of Chlorella protothecoides cultivation. A total of 87 clones were obtained and sequenced, in which 78 clones were homologous to known genes in databases. Among them, the ammonium transporter gene (CpAMT1) was characterized in detail. Quantitative real-time PCR showed that the expression of CpAMT1 was significantly induced by PFA and correlated with lipid accumulation. The up-regulation of CpAMT1 was suppressed by glutamine, while the lipid biosynthesis was also inhibited. Further analysis showed that the expression of CpAMT1 was correlated with glutamine synthetase activity, suggesting that CpAMT1, along with glutamine synthetase/glutamate synthase, may be responsible for nitrogen sensing in C. protothecoides. Together, these results imply that the ammonium transporter CpAMT1 could be the initial sensor of nitrogen deficiency and channels the carbon excess toward lipid biosynthesis.
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