title: Characterization of an ammonium transporter in the oleaginous alga Chlorella protothecoides.
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.
authors.affiliation: School of Life Sciences, Tsinghua University, Beijing 100084, People's Republic of China.
authors.forename: Dong
authors.initials: D
authors.lastname: Yan
authors.forename: Junbiao
authors.initials: J
authors.lastname: Dai
authors.forename: Qingyu
authors.initials: Q
authors.lastname: Wu
mesh_terms: D020418:Algal Proteins / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D002708:Chlorella / Q000187:drug effects / Q000378:metabolism*; D005973:Glutamine / Q000494:pharmacology; D000644:Quaternary Ammonium Compounds / Q000378:metabolism*
chemical_list: D020418:Algal Proteins; D002352:Carrier Proteins; D000644:Quaternary Ammonium Compounds; D005973:Glutamine