TY - JOUR
T1 - Regulation of ammonia homeostasis by the ammonium transporter AmtA in Dictyostelium discoideum
AU - Yoshino, Ryuji
AU - Morio, Takahiro
AU - Yamada, Yoko
AU - Kuwayama, Hidekazu
AU - Sameshima, Masazumi
AU - Tanaka, Yoshimasa
AU - Sesaki, Hiromi
AU - Iijima, Miho
PY - 2007/12
Y1 - 2007/12
N2 - Ammonia has been shown to function as a morphogen at multiple steps during the development of the cellular slime mold Dictyostelium discoideum; however, it is largely unknown how intracellular ammonia levels are controlled. In the Dictyostelium genome, there are five genes that encode putative ammonium transporters: amtA, amtB, amtC, rhgA, and rhgB. Here, we show that AmtA regulates ammonia homeostasis during growth and development. We found that cells lacking amtA had increased levels of ammonia/ammonium, whereas their extracellular ammonia/ammonium levels were highly decreased. These results suggest that AmtA mediates the excretion of ammonium. In support of a role for AmtA in ammonia homeostasis, AmtA mRNA is expressed throughout the life cycle, and its expression level increases during development. Importantly, AmtA-mediated ammonia homeostasis is critical for many developmental processes. amtA- cells are more sensitive to NH4Cl than wild-type cells in inhibition of Chemotaxis toward cyclic AMP and of formation of multicellular aggregates. Furthermore, even in the absence of exogenously added ammonia, we found that amtA- cells produced many small fruiting bodies and that the viability and germination of amtA- spores were dramatically compromised. Taken together, our data clearly demonstrate that AmtA regulates ammonia homeostasis and plays important roles in multiple developmental processes in Dictyostelium.
AB - Ammonia has been shown to function as a morphogen at multiple steps during the development of the cellular slime mold Dictyostelium discoideum; however, it is largely unknown how intracellular ammonia levels are controlled. In the Dictyostelium genome, there are five genes that encode putative ammonium transporters: amtA, amtB, amtC, rhgA, and rhgB. Here, we show that AmtA regulates ammonia homeostasis during growth and development. We found that cells lacking amtA had increased levels of ammonia/ammonium, whereas their extracellular ammonia/ammonium levels were highly decreased. These results suggest that AmtA mediates the excretion of ammonium. In support of a role for AmtA in ammonia homeostasis, AmtA mRNA is expressed throughout the life cycle, and its expression level increases during development. Importantly, AmtA-mediated ammonia homeostasis is critical for many developmental processes. amtA- cells are more sensitive to NH4Cl than wild-type cells in inhibition of Chemotaxis toward cyclic AMP and of formation of multicellular aggregates. Furthermore, even in the absence of exogenously added ammonia, we found that amtA- cells produced many small fruiting bodies and that the viability and germination of amtA- spores were dramatically compromised. Taken together, our data clearly demonstrate that AmtA regulates ammonia homeostasis and plays important roles in multiple developmental processes in Dictyostelium.
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U2 - 10.1128/EC.00204-07
DO - 10.1128/EC.00204-07
M3 - Article
C2 - 17951519
AN - SCOPUS:37549049415
SN - 1535-9778
VL - 6
SP - 2419
EP - 2428
JO - Eukaryotic Cell
JF - Eukaryotic Cell
IS - 12
ER -