Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
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Gene/Protein
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Target Concepts:
Gene/Protein
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Query: EC:6.4.1.1 (
pyruvate carboxylase
)
1,516
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Cell extracts of the fermentative Mollicutes Acholeplasma laidlawii B-PG9, Acholeplasma morum S2, Mycoplasma capricolum 14, Mycoplasma gallisepticum S6, Mycoplasma pneumoniae FH, Mycoplasma hyopneumoniae J and M. genitalium G-37, and the non-fermentative Mycoplasma hominis PG-21, Mycoplasma hominis 1620 and Mycoplasma bovigenitalium PG-11 were examined for 39 cytoplasmic enzyme activities associated with the tricarboxylic acid (TCA) cycle, transamination, anaplerotic reactions and other enzyme activities at the pyruvate locus. Malate dehydrogenase (EC 4.2.1.2) was the only TCA-cycle-associated enzyme activity detected and it was found only in the eight Mycoplasma species. Aspartate aminotransferase (EC 2.6.1.1) activity was detected in all Mollicutes tested except M. gallisepticum S6. Malate synthetase (EC 4.1.3.2) activity, in the direction of malate formation, was found in the eight Mycoplasma species, but not in any of the Acholeplasma species. Phosphoenolpyruvate (PEP) carboxylase (EC 4.1.1.31) was detected in the direction of oxaloacetate (OAA) formation in both Acholeplasma species, but not in any of the Mycoplasma species.
Pyruvate carboxylase
(
EC 6.4.1.1
), pyruvate kinase (EC 2.7.1.40), pyruvate dehydrogenase (EC 1.2.4.1) and lactate dehydrogenase (EC 1.1.1.27) activities were found in all ten Mollicutes tested. No activities were detected in any of the ten Mollicutes for aspartase (EC 4.3.1.1), malic enzyme (EC 1.1.1.40), PEP carboxytransphosphorylase (EC 4.1.1.38), PEP carboxykinase (EC 4.1.1.32) or pyruvate orthophosphate dikinase (
EC 2.7.9.1
). In these TCA-cycle-deficient Mollicutes the pyruvate-OAA locus may be a point of linkage for the carbons of glycolysis, lipid synthesis, nucleic acid synthesis and certain amino acids. CO2 fixation appears obligatory in the Acholeplasma species and either CO2 fixation or malate synthesis appears obligatory in the Mycoplasma species.
...
PMID:Presence of anaplerotic reactions and transamination, and the absence of the tricarboxylic acid cycle in mollicutes. 314 76
A full-length transcript for
pyruvate, orthophosphate dikinase
(
PPDK
;
EC 2.7.9.1
), has been characterized from Mesembryanthemum crystallinum. Under salt stress or with increasing age, this plant shows a transition from C3 to Crassulacean acid metabolism (CAM). The
PPDK
plays a central role in gluconeogenesis during the light phase of CAM. The transcript is 3165 bases in length with a single open reading frame of 2739 nucleotides specifying a protein of molecular mass 103098, including a transit peptide of mass 7902 for chloroplast import. The protein shares 44-77% sequence identity with
PPDK
from C4-plants and microorganisms. Known functional and regulatory amino acids are conserved. Southern-type hybridizations indicated one copy or very few closely related copies of the gene per haploid genome. We investigated the induction of
PPDK
at the mRNA and protein levels, using the well characterized induction of a CAM-form of phosphoenol
pyruvate carboxylase
(PEPCase) as internal standard. During wilting of excised leaves PEPCase mRNA amounts increased strongly within 8 h. Under these conditions amounts of
PPDK
mRNA remained constant. Re-hydrating leaves from previously stressed plants led to a decrease in PEPCase and
PPDK
mRNA amounts. During salt stress, no correlation between PEPCase and
PPDK
was observed. Analysis of plants of different ages indicated that, even in well-watered plants,
PPDK
-specific protein and mRNA increased when the plants reached a certain age. In old plants, salt stress failed to further increase
PPDK
mRNA or protein levels.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Age-dependent induction of pyruvate, orthophosphate dikinase in Mesembryanthemum crystallinum L. 764 83
Transgenic rice plants expressing the maize phosphoeno/
pyruvate carboxylase
(PEPC) and
pyruvate, orthophosphate dikinase
(
PPDK
) exhibit a higher photosynthetic capacity (up to 35%) than untransformed plants. The increased photosynthetic capacity in these plants is mainly associated with an enhanced stomatal conductance and a higher internal CO2 concentration. Plants simultaneously expressing high levels of both enzymes also have a higher photosynthetic capacity. The results suggest that both PEPC and
PPDK
play a key role in organic acid metabolism in the guard cells to regulate stomatal opening. Under photoinhibitory and photooxidative conditions, PEPC transgenic rice plants are capable of maintaining a higher photosynthetic rate, a higher photosynthetic quantum yield by PSII and a higher capacity to dissipate excess energy photochemically and non-photochemically than untransformed plants. Preliminary data from field trials show that relative to untransformed plants, the grain yield is about 10-20% higher in selected PEPC and 30-35% higher in
PPDK
transgenic rice plants, due to increased tiller number. Taken together, these results suggest that introduction of C4 photosynthesis enzymes into rice has a good potential to enhance its tolerance to stress, photosynthetic capacity and yield.
...
PMID:Introduction of genes encoding C4 photosynthesis enzymes into rice plants: physiological consequences. 1138 72
Introduction of a C
4
photosynthetic pathway into C
3
rice (
Oryza sativa
) requires installation of a biochemical pump that concentrates CO
2
at the site of carboxylation in modified bundle sheath cells. To investigate the feasibility of this, we generated a quadruple line that simultaneously accumulates four of the core C
4
photosynthetic enzymes from the NADP-malic enzyme subtype, phospho
enol
pyruvate carboxylase
(
Zm
PEPC), NADP-malate dehydrogenase (
Zm
NADP-MDH), NADP-malic enzyme (
Zm
NADP-ME), and pyruvate phosphate dikinase (
Zm
PPDK
). This led to enhanced enzyme activity and mild phenotypic perturbations but was largely neutral in its effects on photosynthetic rate. Measurements of the flux of
13
CO
2
through photosynthetic metabolism revealed a significant increase in the incorporation of
13
C into malate, consistent with increased fixation of
13
CO
2
via PEP carboxylase in lines expressing the maize PEPC enzyme. However, there was no significant differences in labeling of 3-phosphoglycerate (3PGA) indicating that there was no carbon flux through NADP-ME into the Calvin-Benson cycle. There was also no significant difference in labeling of phospho
enol
pyruvate (PEP) indicating that there was no carbon flux through
PPDK
. Crossing the quadruple line with a line with reduced glycine decarboxylase H-protein (
Os
GDCH) abundance led to a photosynthetic phenotype characteristic of the reduced
Os
GDCH line and higher labeling of malate, aspartate and citrate than in the quintuple line. There was evidence of
13
C labeling of aspartate indicating
13
CO
2
fixation into oxaloacetate by PEPC and conversion to aspartate by the endogenous aspartate aminotransferase activity. While Kranz anatomy or other anatomical modifications have not yet been installed in these plants to enable a fully functional C
4
cycle, these results demonstrate for the first-time a partial flux through the carboxylation phase of NADP-ME C
4
metabolism in transgenic rice containing two of the key metabolic steps in the C
4
pathway.
...
PMID:A Partial C
4
Photosynthetic Biochemical Pathway in Rice. 3317 34
