title: Functional expression, purification and reconstitution of the recombinant phosphate transporter Pho89 of Saccharomyces cerevisiae.
abstract: The Saccharomyces cerevisiae high-affinity phosphate transporter Pho89 is a member of the inorganic phosphate (Pi) transporter (PiT) family, and shares significant homology with the type III Na(+)/Pi symporters, hPit1 and hPit2. Currently, detailed biochemical and biophysical analyses of Pho89 to better understand its transport mechanisms are limited, owing to the lack of purified Pho89 in an active form. In the present study, we expressed functional Pho89 in the cell membrane of Pichia pastoris, solubilized it in Triton X-100 and foscholine-12, and purified it by immobilized nickel affinity chromatography combined with size exclusion chromatography. The protein eluted as an oligomer on the gel filtration column, and SDS/PAGE followed by western blotting analysis revealed that the protein appeared as bands of approximately 63, 140 and 520 kDa, corresponding to the monomeric, dimeric and oligomeric masses of the protein, respectively. Proteoliposomes containing purified and reconstituted Pho89 showed Na(+)-dependent Pi transport activity driven by an artificially imposed electrochemical Na(+) gradient. This implies that Pho89 operates as a symporter. Moreover, its activity is sensitive to the Na(+) ionophore monensin. To our knowledge, this study represents the first report on the functional reconstitution of a Pi-coupled PiT family member.
authors.affiliation: School of Natural Sciences, Linnaeus University, Kalmar, Sweden.
authors.forename: Palanivelu
authors.initials: P
authors.lastname: Sengottaiyan
authors.forename: Lorena
authors.initials: L
authors.lastname: Ruiz-Pavón
authors.forename: Bengt L
authors.initials: BL
authors.lastname: Persson
mesh_terms: D001692:Biological Transport / Q000187:drug effects; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D055664:Electrochemical Techniques; D004591:Electrophoresis, Polyacrylamide Gel; D008970:Molecular Weight; D008985:Monensin / Q000494:pharmacology; D017830:Octoxynol / Q000737:chemistry; D010710:Phosphates / Q000378:metabolism; D010767:Phosphorylcholine / Q000031:analogs & derivatives / Q000737:chemistry; D010843:Pichia / Q000235:genetics; D055503:Protein Multimerization; D011510:Proteolipids / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D061210:Sodium Ionophores / Q000494:pharmacology; D050611:Sodium-Phosphate Cotransporter Proteins, Type III / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012995:Solubility
chemical_list: C493567:PHO89 protein, S cerevisiae; D010710:Phosphates; D011510:Proteolipids; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D061210:Sodium Ionophores; D050611:Sodium-Phosphate Cotransporter Proteins, Type III; C020485:proteoliposomes; D010767:Phosphorylcholine; C028810:dodecylphosphocholine; D017830:Octoxynol; D008985:Monensin