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Redundancy in the function of mitochondrial phosphate transport in Saccharomyces cerevisiae and Arabidopsis thaliana
Author(s) -
Hamel Patrice,
SaintGeorges Yann,
De Pinto Brigida,
Lachacinski Nicole,
Altamura Nicola,
Dujardin Geneviève
Publication year - 2004
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2003.03810.x
Subject(s) - saccharomyces cerevisiae , biology , mitochondrion , gene isoform , mutant , arabidopsis thaliana , microbiology and biotechnology , inner mitochondrial membrane , gene , biochemistry , gene expression
Summary Most cellular ATP is produced within the mitochondria from ADP and Pi which are delivered across the inner‐membrane by specific nuclearly encoded polytopic carriers. In Saccharomyces cerevisiae, some of these carriers and in particular the ADP/ATP carrier, are represented by several related isoforms that are distinct in their pattern of expression. Until now, only one mitochondrial Pi carrier (mPic) form, encoded by the MIR1 gene in S. cerevisiae, has been described. Here we show that the gene product encoded by the YER053C ORF also participates in the delivery of phosphate to the mitochondria. We have called this gene PIC2 for Pi carrier isoform 2. Overexpression of PIC2 compensates for the mitochondrial defect of the double mutant Δmir1 Δpic2 and restores phosphate transport activity in mitochondria swelling experiments. The existence of two isoforms of mPic does not seem to be restricted to S. cerevisiae as two Arabidopsis thaliana cDNAs encoding two different mPic‐like proteins are also able to complement the double mutant Δmir1 Δpic2 . 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.