The dicarboxylate carrier (Dic) is an important member of mitochondrial carrier family, which catalyzes an electroneutral exchange of dicarboxylates for inorganic phosphate or sulfur containing compounds. In yeast and mammals Dic is present as a single protein, while the screening of Flybase database allowed us to identify four Dic related proteins in Drosophila melanogaster (DmDicp). A phylogenetic analysis on these proteins revealed that DmDic1-4 proteins are monophyletic and form a group with all Dics. We investigated the DmDIC gene expression finding out that DmDIC1 is expressed in all D.melanogaster developmental stages, DmDIC2 is completely absent, whereas DmDIC3 and DmDIC4 expression is limited to the pupal stage. We then studied the biochemical properties of DmDic 1-3-4 proteins in a reconstituted system (proteoliposomes). Our findings demonstrate that DmDic1p is the D. melanogaster homolog of the human Dic and shows similar substrate specificity and inhibitor sensitivity of mammalian and yeast mitochondrial Dics. Interestingly, DmDic3p seems to be an atypical dicarboxylate carrier, being able to transport only phosphate, sulphate and tiosulphate. However, its exclusive presence in the pupal stage, its low affinity for phosphate and its low similarity with the known phosphate carriers led us to exclude that DmDic3p is the main D. melanogaster phosphate carrier. We did not observe any transport activity for DmDic4p, which may be explained by the lack of selective pressure upon its gene copy that could have been free to mutate and acquire a new function which remains to be determined. These outcomes have been supported by modelling and structural alignment analyses using as template the well-characterized bovine mitochondrial oxoglutarate carrier (OGC), which confirmed the apparently weird behaviour of DmDic3p respect to DmDic1p and gave us a potential explanation of the lack of dicarboxylate or phosphate transport activity of DmDic4p.
Madeo M, Tasco G, Carrisi C, Curcio R, Martello E, Santoro A, et al. (2011). Identification and characterization of a novel subfamily of mitochondrial dicarboxylate carriers of Drosophila melanogaster.
Identification and characterization of a novel subfamily of mitochondrial dicarboxylate carriers of Drosophila melanogaster
TASCO, GIANLUCA;CASADIO, RITA;
2011
Abstract
The dicarboxylate carrier (Dic) is an important member of mitochondrial carrier family, which catalyzes an electroneutral exchange of dicarboxylates for inorganic phosphate or sulfur containing compounds. In yeast and mammals Dic is present as a single protein, while the screening of Flybase database allowed us to identify four Dic related proteins in Drosophila melanogaster (DmDicp). A phylogenetic analysis on these proteins revealed that DmDic1-4 proteins are monophyletic and form a group with all Dics. We investigated the DmDIC gene expression finding out that DmDIC1 is expressed in all D.melanogaster developmental stages, DmDIC2 is completely absent, whereas DmDIC3 and DmDIC4 expression is limited to the pupal stage. We then studied the biochemical properties of DmDic 1-3-4 proteins in a reconstituted system (proteoliposomes). Our findings demonstrate that DmDic1p is the D. melanogaster homolog of the human Dic and shows similar substrate specificity and inhibitor sensitivity of mammalian and yeast mitochondrial Dics. Interestingly, DmDic3p seems to be an atypical dicarboxylate carrier, being able to transport only phosphate, sulphate and tiosulphate. However, its exclusive presence in the pupal stage, its low affinity for phosphate and its low similarity with the known phosphate carriers led us to exclude that DmDic3p is the main D. melanogaster phosphate carrier. We did not observe any transport activity for DmDic4p, which may be explained by the lack of selective pressure upon its gene copy that could have been free to mutate and acquire a new function which remains to be determined. These outcomes have been supported by modelling and structural alignment analyses using as template the well-characterized bovine mitochondrial oxoglutarate carrier (OGC), which confirmed the apparently weird behaviour of DmDic3p respect to DmDic1p and gave us a potential explanation of the lack of dicarboxylate or phosphate transport activity of DmDic4p.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
