Glyoxysomal malate dehydrogenase from watermelon is synthesized with an amino-terminal transit peptide.

Gietl, Christine

doi:10.1073/pnas.87.15.5773

Cited by 106 publications

(64 citation statements)

References 37 publications

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“…1). It is important to note that the AtLACS6 is synthesized as larger precursor containing a cleavable aminoterminal presequence, as is the case for some other plant glyoxysomal proteins, such as malate dehydrogenase (Gietl, 1990;Kato et al, 1998), citrate synthase (Kato et al, 1995), thiolase (Preisig-Mü ller and Kindle, 1993; Kato et al, 1996b), and LACX (Hayashi et al, 1998). This further confirms the importance of the PTS2 signal for protein import in plant glyoxysomes.…”

Section: Discussionmentioning

confidence: 64%

Molecular Characterization of an Arabidopsis Acyl-Coenzyme A Synthetase Localized on Glyoxysomal Membranes

et al. 2002

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In higher plants, fat-storing seeds utilize storage lipids as a source of energy during germination. To enter the β-oxidation pathway, fatty acids need to be activated to acyl-coenzyme As (CoAs) by the enzyme acyl-CoA synthetase (ACS; EC 6.2.1.3). Here, we report the characterization of an Arabidopsis cDNA clone encoding for a glyoxysomal acyl-CoA synthetase designatedAtLACS6. The cDNA sequence is 2,106 bp long and it encodes a polypeptide of 701 amino acids with a calculated molecular mass of 76,617 D. Analysis of the amino-terminal sequence indicates that acyl-CoA synthetase is synthesized as a larger precursor containing a cleavable amino-terminal presequence so that the mature polypeptide size is 663 amino acids. The presequence shows high similarity to the typical PTS2 (peroxisomal targeting signal 2). TheAtLACS6 also shows high amino acid identity to prokaryotic and eukaryotic fatty acyl-CoA synthetases. Immunocytochemical and cell fractionation analyses indicated that theAtLACS6 is localized on glyoxysomal membranes.AtLACS6 was overexpressed in insect cells and purified to near homogeneity. The purified enzyme is particularly active on long-chain fatty acids (C16:0). Results from immunoblot analysis revealed that the expression of both AtLACS6 and β-oxidation enzymes coincide with fatty acid degradation. These data suggested that AtLACS6 might play a regulatory role both in fatty acid import into glyoxysomes by making a complex with other factors, e.g. PMP70, and in fatty acid β-oxidation activating the fatty acids.

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Section: Discussionmentioning

confidence: 64%

Molecular Characterization of an Arabidopsis Acyl-Coenzyme A Synthetase Localized on Glyoxysomal Membranes

et al. 2002

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“…cDNA cloning Approximately 500 000 PFU of an alfalfa nodule cDNA library (Gregerson et al, 1993) were screened by hybridization with the inserts from watermelon mMDH (Gietl, 1992) and gMDH (Gietl, 1990) cDNAs. Positively hybridizing phage were purified, DNA was extracted, and inserts large enough to potentially contain the entire MDH coding region were subcloned into pBluescript.…”

Section: Methodsmentioning

confidence: 99%

Alfalfa malate dehydrogenase (MDH): molecular cloning and characterization of five different forms reveals a unique nodule‐enhanced MDH

Miller¹,

Driscoll²,

Gregerson³

et al. 1998

The Plant Journal

151

100

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SummaryMalate dehydrogenase (MDH) catalyzes the readily reversible reaction of oxaloacetate ≤ malate using either NADH or NADPH as a reductant. In plants, the enzyme is important in providing malate for C 4 metabolism, pH balance, stomatal and pulvinal movement, respiration, β-oxidation of fatty acids, and legume root nodule functioning. Due to its diverse roles the enzyme occurs as numerous isozymes in various organelles. While antibodies have been produced and cDNAs characterized for plant mitochondrial, glyoxysomal, and chloroplast forms of MDH, little is known of other forms. Here we report the cloning and characterization of cDNAs encoding five different forms of alfalfa MDH, including a plant cytosolic MDH (cMDH) and a unique novel nodule-enhanced MDH (neMDH). Phylogenetic analyses show that neMDH is related to mitochondrial and glyoxysomal MDHs, but diverge from these forms early in land plant evolution. Four of the five forms could effectively complement an E. coli Mdh -mutant. RNA and protein blots show that neMDH is most highly expressed in effective root nodules. Immunoprecipitation experiments show that antibodies produced to cMDH and neMDH are immunologically distinct and that the neMDH form comprises the major form of total MDH activity and protein in root nodules. Kinetic analysis showed that neMDH has a turnover rate and specificity constant that can account for the extraordinarily high synthesis of malate in nodules.

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“…It is known that not only thiolase but also malate dehydrogenase and citrate synthase are synthesized as precursor proteins with an N-terminal presequence in plant cells (Gietl, 1990;Kato et al, 1995). These N-terminal presequences contain the consensus sequence (R)-(L/Q/I)-X 5 -(H)-(L) designated PTS2 (where X stands for any of amino acid and PTS stands for peroxisomal targeting signal), which functions as a targeting signal for plant peroxisomes (Kato et al, 1996a).…”

Section: Relationship Between the Ped2 Gene And Phenotype Of Ped2/pedmentioning

confidence: 99%

2,4-Dichlorophenoxybutyric Acid–Resistant Mutants of Arabidopsis Have Defects in Glyoxysomal Fatty Acid β-Oxidation

et al. 1998

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It has been demonstrated previously that 2,4-dichlorophenoxybutyric acid (2,4-DB) is metabolized to produce a herbicide, 2,4-D, by the action of peroxisomal fatty acid ␤ -oxidation in higher plants. To isolate mutants that have defects in peroxisomal fatty acid ␤ -oxidation, we screened mutant lines of Arabidopsis seedlings for growth in the presence of toxic levels of 2,4-DB. Twelve of the mutants survived; of these, four required sucrose for postgerminative growth. This result suggests that these mutants have defects in peroxisomal fatty acid ␤ -oxidation, because peroxisomal fatty acid ␤ -oxidation plays an important role in producing sucrose from storage lipids during germination. Genetic analysis revealed that these mutants can be classified as carrying alleles at three independent loci, which we designated ped1 , ped2 , and ped3 , respectively (where ped stands for peroxisome defective). The ped1 mutant lacks the thiolase protein, an enzyme involved in fatty acid ␤ -oxidation during germination and subsequent seedling growth, whereas the ped2 mutant has a defect in the intracellular transport of thiolase from the cytosol to glyoxysomes. Etiolated cotyledons of both ped1 and ped2 mutants have glyoxysomes with abnormal morphology.

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Glyoxysomal malate dehydrogenase from watermelon is synthesized with an amino-terminal transit peptide.

Cited by 106 publications

References 37 publications

Molecular Characterization of an Arabidopsis Acyl-Coenzyme A Synthetase Localized on Glyoxysomal Membranes

Molecular Characterization of an Arabidopsis Acyl-Coenzyme A Synthetase Localized on Glyoxysomal Membranes

Alfalfa malate dehydrogenase (MDH): molecular cloning and characterization of five different forms reveals a unique nodule‐enhanced MDH

2,4-Dichlorophenoxybutyric Acid–Resistant Mutants of Arabidopsis Have Defects in Glyoxysomal Fatty Acid β-Oxidation

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