Efn1 (SPBPB2B2.06c) and Efn2 (SPAC1039.02) are extracellular 5'-nucleotidases induced during the fission yeast response to phosphate starvation
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ABSTRACT: The fission yeast PHO regulon genes pho1, pho84, and tgp1 – encoding a cell surface-associated acid phosphatase (Pho1), a plasma membrane inorganic phosphate transporter (Pho84), and a plasma membrane glycerophosphocholine transporter (Tgp1) – are strongly upregulated in response to acute phosphate starvation, as are the SPBPB2B2.06c and SPAC1039.02 genes that encode putative 5'-nucleotidase paralogs of the binuclear metallophosphoesterase enzyme superfamily. Via proteomic analysis of the medium harvested from phosphate-replete and phosphate-starved fission yeast, we define a starvation secretome that includes SPBPB2B2.06c (renamed Efn1, for extracellular five-prime nucleotidase), SPAC1039.02 (henceforth Efn2), and Pho1 among the most abundant exported proteins elaborated by phosphate-starved cells. We demonstrate and characterize a 5'-nucleotidase activity secreted into the medium of phosphate-starved efn1+ efn2+ cells, which is eliminated by simultaneous deletion of efn1 and efn2. By singly deleting efn1 and efn2, we find that Efn1 contributes the greater share of secreted 5'-nucleotidase activity. Efn1 and Efn2 catalyze the release of inorganic phosphate from all four standard ribonucleoside monophosphates, in order of preference: CMP > UMP >AMP > GMP. Whereas efn1+ efn2+ cells can use extracellular CMP as a source of phosphate during phosphate starvation, efn1∆ efn2∆ cells cannot. The secretion of 5'-nucleotidase enzymes during phosphate limitation is a newly appreciated facet of fission yeast phosphate homeostasis.
INSTRUMENT(S): maXis
ORGANISM(S): Schizosaccharomyces Pombe
SUBMITTER: Zhuoning Li
LAB HEAD: Stewart Shuman
PROVIDER: PXD056330 | Pride | 2024-12-03
REPOSITORIES: pride
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