Characterization of two members of a novel malic enzyme class

Voegele, Ralf T.; Mitsch, Michael J.; Finan, Turlough M.

doi:10.1016/s0167-4838(99)00112-0

Cited by 35 publications

(57 citation statements)

References 35 publications

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“…Extensive biochemical characterization of the DME and TME proteins in bacteria has revealed these enzymes to differ functionally in various respects 1,3,5,6,12,14,15,22,29) . In particular, the molecular background of the different physiological roles of these malic enzymes were investigated using E. coli 12,15,22,29) .…”

Section: Discussionmentioning

confidence: 99%

NAD-Malic Enzyme Affects Nitrogen Fixing Activity of Bradyrhizobium japonicum USDA 110 Bacteroids in Soybean Nodules

et al. 2008

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The NAD + -dependent malic enzyme (DME) has been reported to play a key role supporting nitrogenase activity in bacteroids of Sinorhizobium meliloti. Genetic evidence for a similar role in Bradyrhizobium japonicum USDA110 was obtained by constructing a dme mutant. Soybean plants inoculated with a dme mutant did not show delayed nodulation, but formed small root nodules and exhibited significant nitrogen-deficiency symptoms. Nodule numbers and the acetylene reducting activity per nodule as a dry weight value 14 and 28 days after inoculation with the dme mutant were comparable to those of plants inoculated with wild-type B. japonicum. However, shoot dry weight and acetylene reducting activity per nodule decreased to ca. 30% of the values in plants with wild-type B. japonicum. The sucrose and organic acid (malate, succinate, acetate, α-ketoglutarate and lactate) contents of the nodules were investigated. Amounts of sucrose, malate and α-ketoglutarate increased on inoculation with the dme mutant, suggesting that the decreased DME and nitrogenase activities in the bacteroids resulted in a reduction in the consumption of these respiratory metabolites by the nodules. The data suggest that the DME activity of B. japonicum bacteroids plays a role in nodule metabolism and supports nitrogen fixation.

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Section: Discussionmentioning

confidence: 99%

NAD-Malic Enzyme Affects Nitrogen Fixing Activity of Bradyrhizobium japonicum USDA 110 Bacteroids in Soybean Nodules

et al. 2008

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“…Malate oxidation could only be coupled to NADP + reduction at a considerably lower rate [34 Table 2). Addition of acetylCoA caused a complete loss of this activity, which is characteristic for some NADP + -dependent dehydrogenases decarboxylating malate to pyruvate (malic enzymes; Voegele et al 1999). In contrast to the NADP + -dependent enzyme, the presence of an NAD + -reducing malate dehydrogenase that operates in the oxidative direction [220 nmol min -1 (mg protein) -1 ] could only be revealed after addition of acetyl-CoA to scavenge oxaloacetate in the exergonic reaction of citrate formation.…”

Section: Acetate Oxidation In Pure Culturementioning

confidence: 99%

Oxidation of acetate through reactions of the citric acid cycle by Geobacter sulfurreducens in pure culture and in syntrophic coculture

Galushko

Schink

2000

Archives of Microbiology

136

163

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Geobacter sulfurreducens strain PCA oxidized acetate to CO 2 via citric acid cycle reactions during growth with acetate plus fumarate in pure culture, and with acetate plus nitrate in coculture with Wolinella succinogenes. Acetate was activated by succinyl-CoA:acetate CoA-transferase and also via acetate kinase plus phosphotransacetylase. Citrate was formed by citrate synthase. Soluble isocitrate and malate dehydrogenases reduced NADP + and NAD + , respectively. Oxidation of 2-oxoglutarate was measured as benzyl viologen reduction and was strictly CoA-dependent; a low activity was also observed with NADP + . Succinate dehydrogenase and fumarate reductase both were membrane-bound. Succinate oxidation was coupled to NADP + reduction whereas fumarate reduction was coupled to NADPH and NADH oxidation. Coupling of succinate oxidation to NADP + or cytochrome(s) reduction required an ATP-dependent reversed electron transport. Net ATP synthesis proceeded exclusively through electron transport phosphorylation. During fumarate reduction, both NADPH and NADH delivered reducing equivalents into the electron transport chain, which contained a menaquinone. Overall, acetate oxidation with fumarate proceeded through an open loop of citric acid cycle reactions, excluding succinate dehydrogenase, with fumarate reductase as the key reaction for electron delivery, whereas acetate oxidation in the syntrophic coculture required the complete citric acid cycle.

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“…A first class of NADP-dependent malic enzymes (EC 1.1.1.40), decarboxylating malate and also oxaloacetate, are found in cytosol, chloroplasts and mitochondria; a second group of enzymes, preferentially utilizing NAD (EC 1.1.1.38), are also capable of decarboxylating oxaloacetate and are found in bacteria and insects; finally, a third class of NAD-dependent malic enzymes (EC 1.1.1.39), unable to use oxaloacetate, have been found only in mitochondrial matrix. In prokaryotes, malic enzymes are also widely distributed (Murai et al, 1971;Diesterhaft & Freese, 1973;Lamed & Zeikus, 1981;Knichel & Radler, 1982;Bartolucci et al, 1987;Kobayashi et al, 1989;Kawai et al, 1996;Voegele et al, 1999). However, few of them have been characterized so far, and in particular, few reports allowed distinction of whether the observed malic enzyme activity resulted from one or several isozymes.…”

Section: Introductionmentioning

confidence: 99%

The Bacillus subtilis ywkA gene encodes a malic enzyme and its transcription is activated by the YufL/YufM two-component system in response to malate

et al. 2003

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A transcriptome comparison of a wild-type Bacillus subtilis strain growing under glycolytic or gluconeogenic conditions was performed. In particular, it revealed that the ywkA gene, one of the four paralogues putatively encoding a malic enzyme, was more transcribed during gluconeogenesis. Using a lacZ reporter fusion to the ywkA promoter, it was shown that ywkA was specifically induced by external malate and not subject to glucose catabolite repression. Northern analysis confirmed this expression pattern and demonstrated that ywkA is cotranscribed with the downstream ywkB gene. The ywkA gene product was purified and biochemical studies demonstrated its malic enzyme activity, which was 10-fold higher with NAD than with NADP (k cat/K m 102 and 10 s−1 mM−1, respectively). However, physiological tests with single and multiple mutant strains affected in ywkA and/or in ywkA paralogues showed that ywkA does not contribute to efficient utilization of malate for growth. Transposon mutagenesis allowed the identification of the uncharacterized YufL/YufM two-component system as being responsible for the control of ywkA expression. Genetic analysis and in vitro studies with purified YufM protein showed that YufM binds just upstream of ywkA promoter and activates ywkA transcription in response to the presence of malate in the extracellular medium, transmitted by YufL. ywkA and yufL/yufM could thus be renamed maeA for malic enzyme and malK/malR for malate kinase sensor/malate response regulator, respectively.

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Characterization of two members of a novel malic enzyme class

Cited by 35 publications

References 35 publications

NAD-Malic Enzyme Affects Nitrogen Fixing Activity of Bradyrhizobium japonicum USDA 110 Bacteroids in Soybean Nodules

NAD-Malic Enzyme Affects Nitrogen Fixing Activity of Bradyrhizobium japonicum USDA 110 Bacteroids in Soybean Nodules

Oxidation of acetate through reactions of the citric acid cycle by Geobacter sulfurreducens in pure culture and in syntrophic coculture

The Bacillus subtilis ywkA gene encodes a malic enzyme and its transcription is activated by the YufL/YufM two-component system in response to malate

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