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General Physiology and Biophysics Sep 2002Malate dehydrogenases (MDH, L-malate:NAD oxidoreductase, EC 1.1.1.37), catalyze the NAD/NADH-dependent interconversion of the substrates malate and oxaloacetate. This... (Review)
Review
Malate dehydrogenases (MDH, L-malate:NAD oxidoreductase, EC 1.1.1.37), catalyze the NAD/NADH-dependent interconversion of the substrates malate and oxaloacetate. This reaction plays a key part in the malate/aspartate shuttle across the mitochondrial membrane, and in the tricarboxylic acid cycle within the mitochondrial matrix. They are homodimeric molecules in most organisms, including all eukaryots and the most bacterial species. The enzymes share a common catalytic mechanism and their kinetic properties are similar, which demonstrates a high degree of structural similarity. The three-dimensional structures and elements essential for catalysis are conserved between mitochondrial and cytoplasmic forms of MDH in eukaryotic cells even though these isoenzymes are only marginally related at the level of primary structure.
Topics: Animals; Archaea; Bacteria; Catalysis; Cytoplasm; Enzyme Stability; Isoenzymes; Malate Dehydrogenase; Mitochondria; NAD; Protein Conformation; Species Specificity; Structure-Activity Relationship
PubMed: 12537350
DOI: No ID Found -
Molecular Cell Dec 2022Inhibition of the electron transport chain (ETC) prevents the regeneration of mitochondrial NAD, resulting in cessation of the oxidative tricarboxylic acid (TCA) cycle...
Inhibition of the electron transport chain (ETC) prevents the regeneration of mitochondrial NAD, resulting in cessation of the oxidative tricarboxylic acid (TCA) cycle and a consequent dependence upon reductive carboxylation for aspartate synthesis. NAD regeneration alone in the cytosol can rescue the viability of ETC-deficient cells. Yet, how this occurs and whether transfer of oxidative equivalents to the mitochondrion is required remain unknown. Here, we show that inhibition of the ETC drives reversal of the mitochondrial aspartate transaminase (GOT2) as well as malate and succinate dehydrogenases (MDH2 and SDH) to transfer oxidative NAD equivalents into the mitochondrion. This supports the NAD-dependent activity of the mitochondrial glutamate dehydrogenase (GDH) and thereby enables anaplerosis-the entry of glutamine-derived carbon into the TCA cycle and connected biosynthetic pathways. Thus, under impaired ETC function, the cytosolic redox state is communicated into the mitochondrion and acts as a rheostat to support GDH activity and cell viability.
Topics: NAD; Malate Dehydrogenase; Oxidation-Reduction; Citric Acid Cycle; Respiration
PubMed: 36327975
DOI: 10.1016/j.molcel.2022.10.005 -
Plant Biology (Stuttgart, Germany) Jan 2019Malate valves act as powerful systems for balancing the ATP/NAD(P)H ratio required in various subcellular compartments in plant cells. As components of malate valves,... (Review)
Review
Malate valves act as powerful systems for balancing the ATP/NAD(P)H ratio required in various subcellular compartments in plant cells. As components of malate valves, isoforms of malate dehydrogenases (MDHs) and dicarboxylate translocators catalyse the reversible interconversion of malate and oxaloacetate and their transport. Depending on the co-enzyme specificity of the MDH isoforms, either NADH or NADPH can be transported indirectly. Arabidopsis thaliana possesses nine genes encoding MDH isoenzymes. Activities of NAD-dependent MDHs have been detected in mitochondria, peroxisomes, cytosol and plastids. In addition, chloroplasts possess a NADP-dependent MDH isoform. The NADP-MDH as part of the 'light malate valve' plays an important role as a poising mechanism to adjust the ATP/NADPH ratio in the stroma. Its activity is strictly regulated by post-translational redox-modification mediated via the ferredoxin-thioredoxin system and fine control via the NADP /NADP(H) ratio, thereby maintaining redox homeostasis under changing conditions. In contrast, the plastid NAD-MDH ('dark malate valve') is constitutively active and its lack leads to failure in early embryo development. While redox regulation of the main cytosolic MDH isoform has been shown, knowledge about regulation of the other two cytosolic MDHs as well as NAD-MDH isoforms from peroxisomes and mitochondria is still lacking. Knockout mutants lacking the isoforms from chloroplasts, mitochondria and peroxisomes have been characterised, but not much is known about cytosolic NAD-MDH isoforms and their role in planta. This review updates the current knowledge on MDH isoforms and the shuttle systems for intercompartmental dicarboxylate exchange, focusing on the various metabolic functions of these valves.
Topics: Cell Respiration; Chloroplasts; Malate Dehydrogenase; Malates; Multigene Family; NAD
PubMed: 29933514
DOI: 10.1111/plb.12869 -
International Journal of Molecular... Sep 2022Malate dehydrogenase, which facilitates the reversible conversion of malate to oxaloacetate, is essential for energy balance, plant growth, and cold and salt tolerance....
Malate dehydrogenase, which facilitates the reversible conversion of malate to oxaloacetate, is essential for energy balance, plant growth, and cold and salt tolerance. However, the genome-wide study of the MDH family has not yet been carried out in tomato (Solanum lycopersicum L.). In this study, 12 MDH genes were identified from the S. lycopersicum genome and renamed according to their chromosomal location. The tomato MDH genes were split into five groups based on phylogenetic analysis and the genes that clustered together showed similar lengths, and structures, and conserved motifs in the encoded proteins. From the 12 tomato MDH genes on the chromosomes, three pairs of segmental duplication events involving four genes were found. Each pair of genes had a Ka/Ks ratio < 1, indicating that the MDH gene family of tomato was purified during evolution. Gene expression analysis exhibited that tomato MDHs were differentially expressed in different tissues, at various stages of fruit development, and differentially regulated in response to abiotic stresses. Molecular docking of four highly expressed MDHs revealed their substrate and co-factor specificity in the reversible conversion process of malate to oxaloacetate. Further, co-localization of tomato MDH genes with quantitative trait loci (QTL) of salt stress-related phenotypes revealed their broader functions in salt stress tolerance. This study lays the foundation for functional analysis of MDH genes and genetic improvement in tomato.
Topics: Gene Expression Regulation, Plant; Genome-Wide Association Study; Solanum lycopersicum; Malate Dehydrogenase; Malates; Molecular Docking Simulation; Multigene Family; Phylogeny; Plant Proteins; Stress, Physiological
PubMed: 36077425
DOI: 10.3390/ijms231710028 -
The Journal of Biological Chemistry May 2022Oxidation of malate to oxaloacetate, catalyzed by either malate dehydrogenase (Mdh) or malate quinone oxidoreductase (Mqo), is a critical step of the tricarboxylic acid...
Oxidation of malate to oxaloacetate, catalyzed by either malate dehydrogenase (Mdh) or malate quinone oxidoreductase (Mqo), is a critical step of the tricarboxylic acid cycle. Both Mqo and Mdh are found in most bacterial genomes, but the level of functional redundancy between these enzymes remains unclear. A bioinformatic survey revealed that Mqo was not as widespread as Mdh in bacteria but that it was highly conserved in mycobacteria. We therefore used mycobacteria as a model genera to study the functional role(s) of Mqo and its redundancy with Mdh. We deleted mqo from the environmental saprophyte Mycobacterium smegmatis, which lacks Mdh, and found that Mqo was essential for growth on nonfermentable carbon sources. On fermentable carbon sources, the Δmqo mutant exhibited delayed growth and lowered oxygen consumption and secreted malate and fumarate as terminal end products. Furthermore, heterologous expression of Mdh from the pathogenic species Mycobacterium tuberculosis shortened the delayed growth on fermentable carbon sources and restored growth on nonfermentable carbon sources at a reduced growth rate. In M. tuberculosis, CRISPR interference of either mdh or mqo expression resulted in a slower growth rate compared to controls, which was further inhibited when both genes were knocked down simultaneously. These data reveal that exergonic Mqo activity powers mycobacterial growth under nonenergy limiting conditions and that endergonic Mdh activity complements Mqo activity, but at an energetic cost for mycobacterial growth. We propose Mdh is maintained in slow-growing mycobacterial pathogens for use under conditions such as hypoxia that require reductive tricarboxylic acid cycle activity.
Topics: Bacterial Proteins; Carbon; Citric Acid Cycle; Malate Dehydrogenase; Malates; Mycobacterium smegmatis; Oxaloacetic Acid; Oxidoreductases
PubMed: 35337802
DOI: 10.1016/j.jbc.2022.101859 -
Biochimica Et Biophysica Acta. Proteins... Jan 2022Malate dehydrogenase (MDH) catalyzes the conversion of NAD and malate to NADH and oxaloacetate in the citric acid cycle. Eukaryotes have one MDH isozyme that is imported...
Malate dehydrogenase (MDH) catalyzes the conversion of NAD and malate to NADH and oxaloacetate in the citric acid cycle. Eukaryotes have one MDH isozyme that is imported into the mitochondria and one in the cytoplasm. We overexpressed and purified Caenorhabditis elegans cytoplasmic MDH-1 and mitochondrial MDH-2 in E. coli. Our goal was to compare the kinetic and structural properties of these enzymes because C. elegans can survive adverse environmental conditions, such as lack of food and elevated temperatures. In steady-state enzyme kinetics assays, we measured K values for oxaloacetate of 54 and 52 μM and K values for NADH of 61 and 107 μM for MDH-1 and MDH-2, respectively. We partially purified endogenous MDH-1 and MDH-2 from a mixed population of worms and separated them using anion exchange chromatography. Both endogenous enzymes had a K for oxaloacetate similar to that of the corresponding recombinant enzyme. Recombinant MDH-1 and MDH-2 had maximum activity at 40 °C and 35 °C, respectively. In a thermotolerance assay, MDH-1 was much more thermostable than MDH-2. Protein homology modeling predicted that MDH-1 had more intersubunit salt-bridges than mammalian MDH1 enzymes, and these ionic interactions may contribute to its thermostability. In contrast, the MDH-2 homology model predicted fewer intersubunit ionic interactions compared to mammalian MDH2 enzymes. These results suggest that the increased stability of MDH-1 may facilitate its ability to remain active in adverse environmental conditions. In contrast, MDH-2 may use other strategies, such as protein binding partners, to function under similar conditions.
Topics: Animals; Caenorhabditis elegans; Caenorhabditis elegans Proteins; Enzyme Stability; Kinetics; Malate Dehydrogenase; Protein Folding
PubMed: 34619358
DOI: 10.1016/j.bbapap.2021.140722 -
Plant Physiology Mar 2022The content of organic acids greatly influences the taste and storage life of fleshy fruit. Our current understanding of the molecular mechanism of organic acid...
The content of organic acids greatly influences the taste and storage life of fleshy fruit. Our current understanding of the molecular mechanism of organic acid accumulation in apple (Malus domestica) fruit focuses on the aluminum-activated malate transporter 9/Ma1 gene. In this study, we identified a candidate gene, MdWRKY126, for controlling fruit acidity independent of Ma1 using homozygous recessive mutants of Ma1, namely Belle de Boskoop "BSKP" and Aifeng "AF." Analyses of transgenic apple calli and flesh and tomato (Solanum lycopersicum) fruit demonstrated that MdWRKY126 was substantially associated with malate content. MdWRKY126 was directly bound to the promoter of the cytoplasmic NAD-dependent malate dehydrogenase MdMDH5 and promoted its expression, thereby enhancing the malate content of apple fruit. In MdWRKY126 overexpressing calli, the mRNA levels of malate-associated transporters and proton pump genes also significantly increased, which contributed to the transport of malate accumulated in the cytoplasm to the vacuole. These findings demonstrated that MdWRKY126 regulates malate anabolism in the cytoplasm and coordinates the transport between cytoplasm and vacuole to regulate malate accumulation. Our study provides useful information to improve our understanding of the complex mechanism regulating apple fruit acidity.
Topics: Fruit; Gene Expression Regulation, Plant; Malate Dehydrogenase; Malates; Malus; Plant Proteins
PubMed: 35078249
DOI: 10.1093/plphys/kiac023 -
Scientific Reports Aug 2020The liver fluke zoonoses, Fasciola spp. are parasitic helminths infecting humans and animals globally. Recent sequencing of the genome of Fasciola gigantica has provided...
The liver fluke zoonoses, Fasciola spp. are parasitic helminths infecting humans and animals globally. Recent sequencing of the genome of Fasciola gigantica has provided a basis to understand the biochemistry of this parasite. Here, we identified the cytosolic malate dehydrogenase in F. gigantica (FgMDH) and characterized the enzyme biochemically and structurally. F. gigantica encodes a single cytosolic MDH, a key enzyme of the citric acid cycle. It catalyzes the reversible oxidation of malate to oxaloacetate using NAD. The Fgmdh gene was amplified and cloned for expression of the recombinant protein. The purified protein showed a molecular weight of ~ 36 kDa that existed in a dimeric form in solution. The recombinant enzyme was catalytically active as it catalyzed both forward and reverse reactions efficiently. The kinetic parameters were determined for both directions. The structure of FgMDH and human MDH were modeled and validated. The superimposition of both the model structures showed overall structural similarity in the active site loop region, however, the conformation of the residues was different. Molecular docking elucidated the binding sites and affinities of the substrates and cofactors to the enzyme. Simulation of molecular dynamics and principal component analysis indicated the stability of the systems and collective motions, respectively. Understanding the structural and functional properties of MDH is important to better understand the roles of this enzyme in the biochemistry of the parasite.
Topics: Animals; Cloning, Molecular; Cytosol; Fasciola; Humans; Malate Dehydrogenase; Molecular Docking Simulation; Phylogeny; Protein Structure, Secondary; Protein Structure, Tertiary; Recombinant Proteins; Sequence Alignment
PubMed: 32770017
DOI: 10.1038/s41598-020-70202-y -
Protein Science : a Publication of the... Oct 1994Malate dehydrogenases are widely distributed and alignment of the amino acid sequences show that the enzyme has diverged into 2 main phylogenetic groups. Multiple amino... (Comparative Study)
Comparative Study Review
Malate dehydrogenases are widely distributed and alignment of the amino acid sequences show that the enzyme has diverged into 2 main phylogenetic groups. Multiple amino acid sequence alignments of malate dehydrogenases also show that there is a low degree of primary structural similarity, apart from in several positions crucial for nucleotide binding, catalysis, and the subunit interface. The 3-dimensional structures of several malate dehydrogenases are similar, despite their low amino acid sequence identity. The coenzyme specificity of malate dehydrogenase may be modulated by substitution of a single residue, as can the substrate specificity. The mechanism of catalysis of malate dehydrogenase is similar to that of lactate dehydrogenase, an enzyme with which it shares a similar 3-dimensional structure. Substitution of a single amino acid residue of a lactate dehydrogenase changes the enzyme specificity to that of a malate dehydrogenase, but a similar substitution in a malate dehydrogenase resulted in relaxation of the high degree of specificity for oxaloacetate. Knowledge of the 3-dimensional structures of malate and lactate dehydrogenases allows the redesign of enzymes by rational rather than random mutation and may have important commercial implications.
Topics: Amino Acid Sequence; Animals; Biological Evolution; Catalysis; Coenzymes; Malate Dehydrogenase; Molecular Sequence Data; Sequence Alignment; Substrate Specificity
PubMed: 7849603
DOI: 10.1002/pro.5560031027 -
The Plant Cell Aug 2018
Topics: Chloroplasts; Endopeptidases; Malate Dehydrogenase; NAD
PubMed: 29934434
DOI: 10.1105/tpc.18.00474