title: Alternative splicing regulates targeting of malate dehydrogenase in Yarrowia lipolytica.
abstract: Alternative pre-mRNA splicing is a major mechanism contributing to the proteome complexity of most eukaryotes, especially mammals. In less complex organisms, such as yeasts, the numbers of genes that contain introns are low and cases of alternative splicing (AS) with functional implications are rare. We report the first case of AS with functional consequences in the yeast Yarrowia lipolytica. The splicing pattern was found to govern the cellular localization of malate dehydrogenase, an enzyme of the central carbon metabolism. This ubiquitous enzyme is involved in the tricarboxylic acid cycle in mitochondria and in the glyoxylate cycle, which takes place in peroxisomes and the cytosol. In Saccharomyces cerevisiae, three genes encode three compartment-specific enzymes. In contrast, only two genes exist in Y. lipolytica. One gene (YlMDH1, YALI0D16753g) encodes a predicted mitochondrial protein, whereas the second gene (YlMDH2, YALI0E14190g) generates the cytosolic and peroxisomal forms through the alternative use of two 3'-splice sites in the second intron. Both splicing variants were detected in cDNA libraries obtained from cells grown under different conditions. Mutants expressing the individual YlMdh2p isoforms tagged with fluorescent proteins confirmed that they localized to either the cytosolic or the peroxisomal compartment.
authors.affiliation: INRA, UMR 1319 Micalis, F-78352 Jouy-en-Josas, France.
authors.forename: Philomène
authors.initials: P
authors.lastname: Kabran
authors.forename: Tristan
authors.initials: T
authors.lastname: Rossignol
authors.forename: Claude
authors.initials: C
authors.lastname: Gaillardin
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Nicaud
authors.forename: Cécile
authors.initials: C
authors.lastname: Neuvéglise
mesh_terms: D017398:Alternative Splicing / Q000235:genetics*; D002952:Citric Acid Cycle / Q000235:genetics; D003600:Cytosol / Q000201:enzymology; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D007438:Introns / Q000235:genetics; D008291:Malate Dehydrogenase / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology; D020675:Peroxisomes / Q000201:enzymology; D010802:Phylogeny; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D025062:Yarrowia / Q000201:enzymology / Q000235:genetics*
chemical_list: D005656:Fungal Proteins; D012322:RNA Precursors; D008291:Malate Dehydrogenase