Redundancy in the function of mitochondrial phosphate transport in Saccharomyces cerevisiae and Arabidopsis thaliana

Abstract

. Finally, we demonstrate that Pic2p is a mitochondrial protein and that its steady state level increases at high temperature. We propose that Pic2p is a minor form of mPic which plays a role under specific stress conditions.

Copper Import into the Mitochondrial Matrix in Saccharomyces cerevisiae Is Mediated by Pic2, a Mitochondrial Carrier Family Protein

“…7B). Because Pic2 has been previously identified as a secondary phosphate carrier, mitochondria from pic2⌬ cells were assayed for phosphate uptake using an established swelling assay (30). Consistent with previous observations, no defect in phosphate uptake was detected in pic2⌬ mitochondria (data not shown).…”

“…Pic2 has been previously implicated in phosphate transport in yeast, as multicopy PIC2 could reverse a mir1⌬pic2⌬ growth defect on a non-fermentable carbon source and rescue phosphate transport in mir1⌬pic2⌬ mitochondria as assayed by mitochondrial swelling (30,36). PIC2 has also been identified as a high copy suppressor of the mitochondrial K ϩ /H ϩ exchanger mutant (mdm38⌬) of yeast (37).…”

Novel Components of an Active Mitochondrial K+/H+ Exchange

“…3A, round dotted line). Interestingly, when K 2 HPO 4 was used as K ϩ salt instead of KCl, K ϩ fluxes were not significantly re-established, whereas H ϩ fluxes reached wild-type levels (data not shown), which are consistent with the role of Pic2 as PO 4 Ϫ /H ϩ transporter (23 Ydl183cp Is an Integral Mitochondrial Protein-YDL183c encodes a protein of 320 amino acids with a molecular mass of about 37 kDa. The computer programs DAS and TMPRED (available on line) predict one transmembrane domain (196 -212 amino acids) and a potential N-terminal mitochondrial targeting sequence.…”

“…Among the suppressors, we found three previously described genes, PIC2, MRS3, and MRS7, encoding mitochondrial proteins. PIC2 and MRS3 encode mitochondrial carrier proteins involved in P i transport and Fe 2ϩ accumulation, respectively (23,24). MRS7 encodes a functional homologue of Mdm38p, located in the inner membrane of mitochondria, with a weak deletion phenotype depending on the strain (7,8).…”

The mitochondrial phosphate carrier: Role in oxidative metabolism, calcium handling and mitochondrial disease

“…PIC2 encodes a second mitochondrial Pi carrier in yeast and also in Arabidopsis thaliana, shares 40% homology to mir1, and appears to play a role under certain stress conditions [43]. That these yeast mutants fail to thrive specifically when grown in the presence of mitochondrial substrates suggests the relevance of the yeast homologs of the PiC for oxidative phosphorylation.…”