Scientifique 1457, Université Paul Sabatier, 11 8 Route de Narbonne, 31 062 Toulouse .... 'Teulières C, Feuillet C, Boudet AM (1989) Differentiz.1 character-.
Plant Physiol. (1995) 107: 1455-1456
Planf Gene Regisfer
Nucleotide Sequence of a cDNA Encoding Mitochondrial Malate Dehydrogenase from Eucalyptus' Odile Poeydomenge, Michèle Marolda, Alain Michel Boudet*, and Jacqueline Crima-Pettenati
Centre de Biologie et Physiologie Végétales, Unité de Recherche Associée au Centre National de Ia Recherche Scientifique 1457, Université Paul Sabatier, 11 8 Route de Narbonne, 31 062 Toulouse Cédex, France MDH (L-malate-NAD-oxidoreductase, EC 1.1.1.37), which reversibly converts oxaloacetate to malate, is ubiquitous in nature because of its vital role in numerous cellular processes. Eukaryotes contain multiple forms of MDH, involved in different metabolic pathways and located in different subcellular compartments. In higher plants, there are three NAD-dependent forms located in the cytoplasm, the mitochondria, the microbodies, and an NADP-dependent form present in chloroplast. These isoenzymes encoded by different nuclear genes are synthesized in the cytoplasm and imported to their respective organelles. The process is facilitated by the presence of a leader sequence at the amino-terminal end of the precursor protein. mMDH in higher plants participates in three different pathways: (a) the tricarboxylic acid cycle, (b) the conversion of Gly to Ser in cooperation with peroxisomes, and (c) the supply of CO, for fixation in bundle sheath in chloroplasts for C, photosynthesis (Gietl, 1992). In this paper, we report on the isolation and sequencing of a cDNA encoding the complete mMDH of Eucalyptus gunnii. A full-length cDNA (1375 bp) encoding eucalyptus mMDH was isolated by screening a hgtll library generated from cell-suspension culture of E. gunnii, with polyclonal antibodies raised against MDH purified from eucalyptus xylem (M. Campbell, unpublished results). The open reading frame encodes a protein of 347 amino acid residues (calculated M,36.5). The polypeptide is highly homologous (identity: similarity) at the amino acid leve1 with mMDH from watermelon (86.2: 8.1%)(Gietl et al., 1990). A significant homology is also found with mitochondrial MDH from rat (56.2: 19.2%) (Grant et al., 1986), mouse (56.8: 18.9%)(Takeshima et al., 1988), pig (58.6: 16.6%)(Birktoft et al., 1982), and yeast (50.3: 15.9%)(Thompson et al., 1988), as well as with the MDH from Escherichia cozi (55.1: 19.2%) (McAlister-Henn et al., 1987). Like the watermelon mMDH (Gietl et al., 1990), the eucalyptus mMDH contains a 27amino acid presequence at the N-terminal end of precursor protein, which is usual for enzymes targeted to the mitochondria. The sequence conforms to the general observation that mitochondrial transit peptides are rich in posi-
Table 1. Characteristics of cDNA mEUMDH from Eucalyptus gLJI7nii
Biological Material: Eucalyptus gunnii, cell-suspension culture obtained from clone 832 (Teulieres et al., 1989). Location on Chromosome:
Unknown. Gene, Function, Pathway: mEuMDH, MDH (EC 1.1.1.37), oxidation of malate to oxaloacetate in the tricarboxylic acid cycle. Techniques: cDNA library immunoscreening, plasmid sequencing (Sambrook et al., 1989). Method of Identification:
Sequence comparison with mitochondrial MDH from watermelon (Gietl et al., 1990),pig (Birktoft et al., 1982),rat (Grant et al., 1986),mouse (Takeshima et al., 1988),and yeast (Thompson et al., 1988). Features of cDNA Structure: Translational start site at nucleotide 61 and stop site at nucleotide 1 1 01. (G + C) Content: 49.7%. Structural Features of Protein Product: Coding region codes for a polypeptide of 347 amino acids with a calculated molecular mass of 36.5 kD and a predicted pl of 8.8. MDH active signature at position 179 to 191 (kkllg VTTLDVVRAKTFY agkak). Subcellular Localization: Most likely localized in mitochondria as suggested by amino acid comparison with mitochondrial forms from other organisms and presence of an N-terminal extension sharing common features with mitochondrial target sequences. Avai bi I ity of Anti bodies: Polvclonal antibodies.
tively charged amino acid residues (mainly Arg's) and contain few acidic residues and a relatively high content of amino acids with hydroxylated side chains (Hartl et al., 1989; Von Heijen et al., 1989). The amino acid residues involved in catalysis, nucleotide binding, and helices forming the subunit interface, which are entirely conserved in a11 MDHs (Gietl, 1992), are also characterized in the 320amino acid mature eucalyptus MDH.
This work was supported the Centre National de la Recherche Scientifique and the University Paul Sabatier. * Corresponding author; e-mail grima8cict.fr;fax 33-61-55-62-
Received September 1,1994; accepted September 13, 1994. Copyright Clearance Center: 0032-0889/95/ 107/1455/02. The EMBL accession number for the sequence reported in this article is X78800.
10.
Abbreviation: mMDH, mitochondrial malate dehydrogenase. 1455
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LITERATURE ClTED
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Plant Physiol. Vol. 107, 1995
Complete nucleotide sequence of the Escherichia coli gene encoding malate dehydrogenase. Nucleic Acids Res 1 5 45193 Sambrook J, Fritsch EF, Maniatis T (1989) Molecular Cloning: A Laboratory Manual, Ed 2. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY ‘Takeshima H, Joh T, Tsuzuki T, Shimada K, Matsukado Y (1988) Structural organization of the mouse malate deh ydrogenase gene. J Mo1 Biol200 1-11 ‘Teulières C, Feuillet C, Boudet AM (1989) Differentiz.1characteristics of cell suspension cultures initiated from Eucdyptus gunnii clones differing by their frost tolerance. Plant Cell Rep 8 407410 ‘Thompson LM, Sutherland P, Steffan JS, McAlister-Henn L (1988) Gene sequence and primary structure of mi tochondrial malate dehydrogenase from Saccharomyces cerevisiae. Biochemistrp 27: 8393-6400 Von Heijne G, Steppuhn J, Herrmann RG (1989) Dclmain structure of mitochondrial and chloroplast targeting peptides. Eur J Biochem 180 535-545
