RRC ID 6741
Author Yoshino R, Morio T, Yamada Y, Kuwayama H, Sameshima M, Tanaka Y, Sesaki H, Iijima M.
Title Regulation of ammonia homeostasis by the ammonium transporter AmtA in Dictyostelium discoideum.
Journal Eukaryot Cell
Abstract 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 NH(4)Cl 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.
Volume 6(12)
Pages 2419-28
Published 2007-12-1
DOI 10.1128/EC.00204-07
PII EC.00204-07
PMID 17951519
PMC PMC2168237
MeSH Ammonia / metabolism* Animals Biological Transport Cation Transport Proteins / genetics Cation Transport Proteins / metabolism* Cation Transport Proteins / physiology* Cell Communication Gene Expression Regulation* Homeostasis Models, Biological Nucleic Acids / chemistry Phosphorylation Phylogeny Quaternary Ammonium Compounds / chemistry* Signal Transduction
IF 2.992
Times Cited 10
Cellular slime molds G01255