title: High-affinity nitrate/nitrite transporter genes (Nrt2) in Tisochrysis lutea: identification and expression analyses reveal some interesting specificities of Haptophyta microalgae.
abstract: Microalgae have a diversity of industrial applications such as feed, food ingredients, depuration processes and energy. However, microalgal production costs could be substantially improved by controlling nutrient intake. Accordingly, a better understanding of microalgal nitrogen metabolism is essential. Using in silico analysis from transcriptomic data concerning the microalgae Tisochrysis lutea, four genes encoding putative high-affinity nitrate/nitrite transporters (TlNrt2) were identified. Unlike most of the land plants and microalgae, cloning of genomic sequences and their alignment with complementary DNA (cDNA) sequences did not reveal the presence of introns in all TlNrt2 genes. The deduced TlNRT2 protein sequences showed similarities to NRT2 proteins of other phyla such as land plants and green algae. However, some interesting specificities only known among Haptophyta were also revealed, especially an additional sequence of 100 amino acids forming an atypical extracellular loop located between transmembrane domains 9 and 10 and the function of which remains to be elucidated. Analyses of individual TlNrt2 gene expression with different nitrogen sources and concentrations were performed. TlNrt2.1 and TlNrt2.3 were strongly induced by low NO3 (-) concentration and repressed by NH4 (+) substrate and were classified as inducible genes. TlNrt2.2 was characterized by a constitutive pattern whatever the substrate. Finally, TlNrt2.4 displayed an atypical response that was not reported earlier in literature. Interestingly, expression of TlNrt2.4 was rather related to internal nitrogen quota level than external nitrogen concentration. This first study on nitrogen metabolism of T. lutea opens avenues for future investigations on the function of these genes and their implication for industrial applications.
authors: Physiology and Biotechnology of Algae Laboratory, IFREMER, Nantes, 44311, France.
authors: Aurélie
authors: A
authors: Charrier
authors: Physiology and Biotechnology of Algae Laboratory, IFREMER, Nantes, 44311, France.
authors: Jean-Baptiste
authors: JB
authors: Bérard
authors: Physiology and Biotechnology of Algae Laboratory, IFREMER, Nantes, 44311, France.
authors: Gaël
authors: G
authors: Bougaran
authors: Physiology and Biotechnology of Algae Laboratory, IFREMER, Nantes, 44311, France.
authors: Grégory
authors: G
authors: Carrier
authors: Physiology and Biotechnology of Algae Laboratory, IFREMER, Nantes, 44311, France.
authors: Ewa
authors: E
authors: Lukomska
authors: Physiology and Biotechnology of Algae Laboratory, IFREMER, Nantes, 44311, France.
authors: Nathalie
authors: N
authors: Schreiber
authors: Physiology and Biotechnology of Algae Laboratory, IFREMER, Nantes, 44311, France.
authors: Flora
authors: F
authors: Fournier
authors: Physiology and Biotechnology of Algae Laboratory, IFREMER, Nantes, 44311, France.
authors: Aurélie F
authors: AF
authors: Charrier
authors: Physiology and Biotechnology of Algae Laboratory, IFREMER, Nantes, 44311, France.
authors: Catherine
authors: C
authors: Rouxel
authors: Physiology and Biotechnology of Algae Laboratory, IFREMER, Nantes, 44311, France.
authors: Matthieu
authors: M
authors: Garnier
authors: Physiology and Biotechnology of Algae Laboratory, IFREMER, Nantes, 44311, France.
authors: Jean-Paul
authors: JP
authors: Cadoret
authors: Physiology and Biotechnology of Algae Laboratory, IFREMER, Nantes, 44311, France.
authors: Bruno
authors: B
authors: Saint-Jean
mesh_terms: D000595:Amino Acid Sequence; D027321:Anion Transport Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005091:Exons; D017343:Genes, Plant; D007438:Introns; D058086:Microalgae / Q000235:genetics*; D008969:Molecular Sequence Data; D009566:Nitrates / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic
chemical_list: D027321:Anion Transport Proteins; D009566:Nitrates; D009573:Nitrites; D012333:RNA, Messenger