Kinetic mechanism in the direction of oxidative decarboxylation for NAD-malic enzyme from Ascaris suum

Biochemistry ◽  
1984 ◽  
Vol 23 (23) ◽  
pp. 5446-5453 ◽  
Author(s):  
Sang Hoon Park ◽  
Dennis M. Kiick ◽  
Ben G. Harris ◽  
Paul F. Cook
Keyword(s):  
Malic Enzyme ◽  
Ascaris Suum ◽  
Kinetic Mechanism ◽  
Oxidative Decarboxylation

Kinetic mechanism of NADP-malic enzyme from maize leaves

1995 ◽  
Vol 43 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Claudia P. Spampinato ◽  
Carlos S. Andreo
Keyword(s):  
Malic Enzyme ◽  
Kinetic Mechanism ◽  
Maize Leaves

Alternative Substrates for Malic Enzyme:  Oxidative Decarboxylation ofl-Aspartate†

Biochemistry ◽  
2002 ◽  
Vol 41 (40) ◽  
pp. 12200-12203 ◽  
Author(s):  
Dali Liu ◽  
Chi-Ching Hwang ◽  
Paul F. Cook
Keyword(s):  
Malic Enzyme ◽  
Oxidative Decarboxylation ◽  
Alternative Substrates

scholarly journals Identification and Characterization ofMAE1, the Saccharomyces cerevisiae Structural Gene Encoding Mitochondrial Malic Enzyme

1998 ◽  
Vol 180 (11) ◽  
pp. 2875-2882 ◽  
Author(s):  
Eckhard Boles ◽  
Patricia de Jong-Gubbels ◽  
Jack T. Pronk
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Enzyme Activity ◽  
Pyruvate Kinase ◽  
Malic Enzyme ◽  
Fold Increase ◽  
Growth Conditions ◽  
Anaerobic Growth ◽  
Oxidative Decarboxylation ◽  
Mrna Levels ◽  
Malic Enzyme Activity

ABSTRACT Pyruvate, a precursor for several amino acids, can be synthesized from phosphoenolpyruvate by pyruvate kinase. Nevertheless, pyk1 pyk2 mutants of Saccharomyces cerevisiae devoid of pyruvate kinase activity grew normally on ethanol in defined media, indicating the presence of an alternative route for pyruvate synthesis. A candidate for this role is malic enzyme, which catalyzes the oxidative decarboxylation of malate to pyruvate. Disruption of open reading frame YKL029c, which is homologous to malic enzyme genes from other organisms, abolished malic enzyme activity in extracts of glucose-grown cells. Conversely, overexpression ofYKL029c/MAE1 from the MET25 promoter resulted in an up to 33-fold increase of malic enzyme activity. Growth studies with mutants demonstrated that presence of either Pyk1p or Mae1p is required for growth on ethanol. Mutants lacking both enzymes could be rescued by addition of alanine or pyruvate to ethanol cultures. Disruption of MAE1 alone did not result in a clear phenotype. Regulation of MAE1 was studied by determining enzyme activities and MAE1 mRNA levels in wild-type cultures and by measuring β-galactosidase activities in a strain carrying a MAE1::lacZ fusion. Both in shake flask cultures and in carbon-limited chemostat cultures,MAE1 was constitutively expressed. A three- to fourfold induction was observed during anaerobic growth on glucose. Subcellular fractionation experiments indicated that malic enzyme in S. cerevisiae is a mitochondrial enzyme. Its regulation and localization suggest a role in the provision of intramitochondrial NADPH or pyruvate under anaerobic growth conditions. However, since null mutants could still grow anaerobically, this function is apparently not essential.

Metal Ion Activator on Intrinsic Isotope Effects of Hydride Transfer and Decarboxylation in the Reaction Catalyzed by the NAD-Malic Enzyme from Ascaris suum

Biochemistry ◽  
1995 ◽  
Vol 34 (10) ◽  
pp. 3253-3260 ◽  
Author(s):  
William E. Karsten ◽  
Sandya R. Gavva ◽  
Sang-Hoon Park ◽  
Paul F. Cook
Keyword(s):  
Malic Enzyme ◽  
Metal Ion ◽  
Ascaris Suum ◽  
Isotope Effects ◽  
Hydride Transfer

scholarly journals Post-transcriptional regulation of redox homeostasis by the small RNA SHOxi in haloarchaea

2020 ◽  
Author(s):  
Diego Rivera Gelsinger ◽  
Rahul Reddy ◽  
Kathleen Whittington ◽  
Sara Debic ◽  
Jocelyne DiRuggiero
Keyword(s):  
Oxidative Stress ◽  
Malic Enzyme ◽  
Tricarboxylic Acid Cycle ◽  
Redox Homeostasis ◽  
Fine Tuning ◽  
Oxidative Decarboxylation ◽  
Seed Region ◽  
Stem Loop ◽  
Loop Region ◽  
Rna Interaction

ABSTRACTHaloarchaea are highly resistant to oxidative stress, however, a comprehensive understanding of the processes regulating this remarkable response is lacking. Oxidative stress-responsive small non-coding RNAs (sRNAs) have been reported in the model archaeon, Haloferax volcanii, but targets and mechanisms have not been elucidated. Using a combination of high throughput and reverse molecular genetic approaches, we elucidated the functional role of the most up-regulated intergenic sRNA during oxidative stress in H. volcanii, named Small RNA in Haloferax Oxidative Stress (SHOxi). SHOxi was predicted to form a stable secondary structure with a conserved stem-loop region as the potential binding site for trans-targets. NAD-dependent malic enzyme mRNA, identified as a putative target of SHOxi, interacted directly with a putative “seed” region within the predicted stem loop of SHOxi. Malic enzyme is an enzyme of the tricarboxylic acid cycle that catalyzes the oxidative decarboxylation of malate into pyruvate using NAD+ as a cofactor. The destabilization of malic enzyme mRNA, and the decrease in the NAD+/NADH ratio, resulting from the direct RNA-RNA interaction between SHOxi and its trans-target was essential for the survival of H. volcanii to oxidative stress. These findings indicate that SHOxi likely regulates redox homeostasis during oxidative stress by the post-transcriptional destabilization of malic enzyme mRNA. SHOxi-mediated regulation provides evidence that the fine-tuning of metabolic cofactors could be a core strategy to mitigate damage from oxidative stress and confer resistance. This study is the first to establish the regulatory effects of sRNAs on mRNAs during the oxidative stress response in Archaea.

scholarly journals Characterization of an archaeal malic enzyme from the hyperthermophilic archaeonThermococcus kodakaraensisKOD1

Archaea ◽  
2005 ◽  
Vol 1 (5) ◽  
pp. 293-301 ◽  
Author(s):  
Wakao Fukuda ◽  
Yulia Sari Ismail ◽  
Toshiaki Fukui ◽  
Haruyuki Atomi ◽  
Tadayuki Imanaka
Keyword(s):  
Enzyme Activity ◽  
Malic Enzyme ◽  
Hyperthermophilic Archaea ◽  
Oxidative Decarboxylation ◽  
Limited Information ◽  
Gene Encoding ◽  
Malic Enzyme Activity ◽  
Reductive Carboxylation ◽  
Reaction Direction

Although the interconversion between C4 and C3 compounds has an important role in overall metabolism, limited information is available on the properties and regulation of enzymes acting on these metabolites in hyperthermophilic archaea. Malic enzyme is one of the enzymes involved in this interconversion, catalyzing the oxidative decarboxylation of malate to pyruvate as well as the reductive carboxylation coupled with NAD(P)H. This study focused on the enzymatic properties and expression profile of an uncharacterized homolog of malic enzyme identified in the genome of a heterotrophic, hyperthermophilic archaeonT hermococcus kodakaraensisKOD1 (Tk-Mae). The amino acid sequence ofTk-Mae was 52–58% identical to those of malic enzymes from bacteria, whereas the similarities to the eukaryotic homologs were lower. Several catalytically important regions and residues were conserved in the primary structure ofTk-Mae. The recombinant protein, which formed a homodimer, exhibited thermostable malic enzyme activity with strict divalent cation dependency. The enzyme preferred NADP+rather than NAD+, but did not catalyze the decarboxylation of oxaloacetate, unlike the usual NADP-dependent malic enzymes. The apparent Michaelis constant (Km) ofTk-Mae for malate (16.9 mM) was much larger than those of known enzymes, leading to no strong preference for the reaction direction. Transcription of the gene encodingTk-Mae and intracellular malic enzyme activity inT. kodakaraensiswere constitutively weak, regardless of the growth substrates. Possible roles ofTk-Mae are discussed based on these results and the metabolic pathways ofT. kodakaraensisdeduced from the genome sequence.

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