title: Isolation and functional characterization of an ammonium transporter gene, PyAMT1, related to nitrogen assimilation in the marine macroalga Pyropia yezoensis (Rhodophyta).
abstract: Ammonium and nitrate are the primary nitrogen sources in natural environments, and are essential for growth and development in photosynthetic eukaryotes. In this study, we report on the isolation and characterization of an ammonium transporter gene (PyAMT1) which performs a key function in nitrogen (N) metabolism of Pyropia yezoensis thalli. The predicted length of PyAMT1 was 483 amino acids (AAs). The AA sequence included 11 putative transmembrane domains and showed approximately 33-44% identity to algal and plant AMT1 AA sequences. Functional complementation in an AMT-defective yeast mutant indicated that PyAMT1 mediated ammonium transport across the plasma membrane. Expression analysis showed that the PyAMT1 mRNA level was strongly induced by N-deficiency, and was more highly suppressed by resupply of inorganic-N than organic-N. These results suggest that PyAMT1 plays important roles in the ammonium transport system, and is highly regulated in response to external/internal N-status.
authors: Graduate School of Bioresources, Mie University, 1577 Kurima-machiya, Tsu, Mie 514-8507, Japan. Electronic address: kakinuma@bio.mie-u.ac.jp.
authors: Makoto
authors: M
authors: Kakinuma
authors: Graduate School of Bioresources, Mie University, 1577 Kurima-machiya, Tsu, Mie 514-8507, Japan.
authors: Chika
authors: C
authors: Nakamoto
authors: Graduate School of Bioresources, Mie University, 1577 Kurima-machiya, Tsu, Mie 514-8507, Japan.
authors: Kazuki
authors: K
authors: Kishi
authors: Graduate School of Bioresources, Mie University, 1577 Kurima-machiya, Tsu, Mie 514-8507, Japan.
authors: Daniel A
authors: DA
authors: Coury
authors: Graduate School of Bioresources, Mie University, 1577 Kurima-machiya, Tsu, Mie 514-8507, Japan.
authors: Hideomi
authors: H
authors: Amano
mesh_terms: D064751:Ammonium Compounds / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism*; D000461:Rhodophyta / Q000235:genetics / Q000502:physiology*
chemical_list: D064751:Ammonium Compounds; D009584:Nitrogen
keywords: Ammonium transporter; Discoloration; Dissolved inorganic nitrogen; Fertilization; Gene expression; Pyropia yezoensis; Rhodophyta; cDNA cloning