Existence of two malic enzymes in Escherichia coli

Katsuki, Hirohiko; Takeo, Kanji; Kameda, K.; Tanaka, Shōzō

doi:10.1016/s0006-291x(67)80102-5

Cited by 34 publications

(16 citation statements)

References 5 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) .…”

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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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“…coli has been shown to have two distinct malic enzymes (25), and much work has been done on the biochemical characterization of these enzymes. Sanwal (44) proposed that, in E. coli, TME may function in a primarily biosynthetic capacity and that DME has a primarily catabolic function.…”

Section: Discussionmentioning

confidence: 99%

“…Much of that residual bacteroid activity appeared to be due to utilization of NADP ؉ by DME. The functions of DME and the NADP ؉ -dependent malic enzyme are discussed in light of the above results and the growth phenotypes of various tme and dme mutants.Malic enzymes convert malate to pyruvate and CO 2 with the simultaneous reduction of NAD -dependent malic enzymes (DME and TME, respectively) in Escherichia coli (25,44), and Hansen and Juni (21) have isolated mutants of E. coli which lack either DME or both DME and TME. Kobayashi et al.…”

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“…Malic enzymes convert malate to pyruvate and CO 2 with the simultaneous reduction of NAD -dependent malic enzymes (DME and TME, respectively) in Escherichia coli (25,44), and Hansen and Juni (21) have isolated mutants of E. coli which lack either DME or both DME and TME. Kobayashi et al.…”

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confidence: 99%

“…Few reports have distinguished whether the activities result from one or two distinct enzymes. Biochemical studies have clearly shown separate NAD ϩ -and NADP ϩ -dependent malic enzymes (DME and TME, respectively) in Escherichia coli (25,44), and Hansen and Juni (21) have isolated mutants of E. coli which lack either DME or both DME and TME. Kobayashi et al (27) have reported the properties of TME together with the nucleotide sequence of the corresponding gene from Bacillus stearothermophilus.…”

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NADP+ -dependent malic enzyme of Rhizobium meliloti

Driscoll

Finan

1996

J Bacteriol

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The bacterium Rhizobium meliloti, which forms N 2 -fixing root nodules on alfalfa, has two distinct malic enzymes; one is NADP ؉ dependent, while a second has maximal activity when NAD ؉ is the coenzyme. The diphosphopyridine nucleotide (NAD ؉ )-dependent malic enzyme (DME) is required for symbiotic N 2 fixation, likely as part of a pathway for the conversion of C 4 -dicarboxylic acids to acetyl coenzyme A in N 2 -fixing bacteroids. Here, we report the cloning and localization of the tme gene (encoding the triphosphopyridine nucleotide [NADP ؉ ]-dependent malic enzyme) to a 3.7-kb region. We constructed strains carrying insertions within the tme gene region and showed that the NADP ؉ -dependent malic enzyme activity peak was absent when extracts from these strains were eluted from a DEAE-cellulose chromatography column. We found that NADP ؉ -dependent malic enzyme activity was not required for N 2 fixation, as tme mutants induced N 2 -fixing root nodules on alfalfa. Moreover, the apparent NADP ؉ -dependent malic enzyme activity detected in wild-type (N 2 -fixing) bacteroids was only 20% of the level detected in free-living cells. Much of that residual bacteroid activity appeared to be due to utilization of NADP ؉ by DME. The functions of DME and the NADP ؉ -dependent malic enzyme are discussed in light of the above results and the growth phenotypes of various tme and dme mutants.Malic enzymes convert malate to pyruvate and CO 2 with the simultaneous reduction of NAD -dependent malic enzymes (DME and TME, respectively) in Escherichia coli (25,44), and Hansen and Juni (21) have isolated mutants of E. coli which lack either DME or both DME and TME. Kobayashi et al. (27) have reported the properties of TME together with the nucleotide sequence of the corresponding gene from Bacillus stearothermophilus.A TME has been partially purified from Bradyrhizobium japonicum bacteroids (26), which have both DME and TME activities (7,28). Both malic enzyme activities have also been reported in Rhizobium sp. strain NGR234 free-living cells (39) and in both free-living cells and bacteroids of Rhizobium leguminosarum (30).We have been studying the role(s) of the bacterial malic enzymes in symbiotic nitrogen fixation within the alfalfa-Rhizobium meliloti symbiosis (9, 10). C 4 -dicarboxylic acids appear to be the principal source of carbon and energy supplied by the plant to N 2 -fixing bacteria (bacteroids) within root nodules (1,17,41). Bacteroids appear to metabolize C 4 -dicarboxylic acids directly via the citric acid cycle (31,47,48). In bacteroids, acetyl coenzyme A appears to be synthesized via the DME and pyruvate dehydrogenase (9, 30), and R. meliloti dme mutants (lacking DME) induce root nodules which contain bacteria but which fail to fix nitrogen (9).To isolate R. meliloti dme mutants, we constructed a strain within which dme mutations generated a succinate-negative growth phenotype. R. meliloti pckA mutants lack phosphoenolpyruvate carboxykinase (PCK) activity and grow poorly on minimal media with succinate or tricar...

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Das ?Malatenzym? von Lactobacillus plantarum und Leuconostoc mesenteroides

Schutz

Radler

1973

Arch. Mikrobiol.

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Existence of two malic enzymes in Escherichia coli

Cited by 34 publications

References 5 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

NADP+ -dependent malic enzyme of Rhizobium meliloti

Das ?Malatenzym? von Lactobacillus plantarum und Leuconostoc mesenteroides

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