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The SPX domain of the yeast low‐affinity phosphate transporter Pho90 regulates transport activity
Author(s) -
Hürlimann Hans Caspar,
Pinson Benoît,
StadlerWaibel Martha,
Zeeman Samuel C,
Freimoser Florian M
Publication year - 2009
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.1038/embor.2009.105
Subject(s) - phosphate , transporter , biochemistry , immunoprecipitation , yeast , efflux , microbiology and biotechnology , biology , ubiquitin , regulator , function (biology) , chemistry , gene
Yeast has two phosphate‐uptake systems that complement each other: the high‐affinity transporters (Pho84 and Pho89) are active under phosphate starvation, whereas Pho87 and Pho90 are low‐affinity transporters that function when phosphate is abundant. Here, we report new regulatory functions of the amino‐terminal SPX domain of Pho87 and Pho90. By studying truncated versions of Pho87 and Pho90, we show that the SPX domain limits the phosphate‐uptake velocity, suppresses phosphate efflux and affects the regulation of the phosphate signal transduction pathway. Furthermore, split‐ubiquitin assays and co‐immunoprecipitation suggest that the SPX domain of both Pho90 and Pho87 interacts physically with the regulatory protein Spl2. This work suggests that the SPX domain inhibits low‐affinity phosphate transport through a physical interaction with Spl2.