A new erythrose 4-phosphate dehydrogenase coupled assay for transketolase

Naula, Christina; Alibu, Vincent P.; Brock, Janice M.; Veitch, Nicola; Burchmore, Richard; Barrett, Michael P.

doi:10.1016/j.jprot.2007.11.002

Cited by 10 publications

(5 citation statements)

References 21 publications

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“…Conversion of F6P and G3P into E4P and X5P was measured as described in [22] with minor changes. The 200 μ l reaction mixture contained 50 mM Tris/HCl (pH 7.2 or 8.0), 0.1 mM TPP, 2.5 mM β -NAD, 15 mM MgCl 2 , 5 mM CaCl 2 , 10 μ g of E4PDH and 2–3 μ g of recombinant TKL.…”

Section: Methodsmentioning

confidence: 99%

Phosphorylation of Arabidopsis transketolase at Ser428 provides a potential paradigm for the metabolic control of chloroplast carbon metabolism

Rocha

Mehlmer

Stael

et al. 2014

Biochemical Journal

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Calcium is an important second messenger in eukaryotic cells that regulates many different cellular processes. To elucidate calcium regulation in chloroplasts, we identified the targets of calcium-dependent phosphorylation within the stromal proteome. A 73 kDa protein was identified as one of the most dominant proteins undergoing phosphorylation in a calcium-dependent manner in the stromal extracts of both Arabidopsis and Pisum. It was identified as TKL (transketolase), an essential enzyme of both the Calvin–Benson–Bassham cycle and the oxidative pentose phosphate pathway. Calcium-dependent phosphorylation of both Arabidopsis isoforms (AtTKL1 and AtTKL2) could be confirmed in vitro using recombinant proteins. The phosphorylation is catalysed by a stroma-localized protein kinase, which cannot utilize GTP. Phosphorylation of AtTKL1, the dominant isoform in most tissues, occurs at a serine residue that is conserved in TKLs of vascular plants. By contrast, an aspartate residue is present in this position in cyanobacteria, algae and mosses. Characterization of a phosphomimetic mutant (S428D) indicated that Ser428 phosphorylation exerts significant effects on the enzyme's substrate saturation kinetics at specific physiological pH values. The results of the present study point to a role for TKL phosphorylation in the regulation of carbon allocation.

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Section: Methodsmentioning

confidence: 99%

Phosphorylation of Arabidopsis transketolase at Ser428 provides a potential paradigm for the metabolic control of chloroplast carbon metabolism

Rocha

Mehlmer

Stael

et al. 2014

Biochemical Journal

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“…These are typically cytosolic enzymes that have a molecular mass of 70-75 kDa, with the homodimer being the active entity [23]. This class of enzyme uses the cofactor thiamine pyrophosphate and a divalent metal cation to catalyze the cleavage of carbon-carbon bonds to transfer two ketol carbon units from donor ketose sugars, such as ribose-5phosphate or erythrose-4-phosphate, resulting in the production of sedoheptulose-7-phosphate or fructose-6phosphate, respectively [25,42].…”

Section: Sequence Analysismentioning

confidence: 99%

Cloning of the Transketolase Gene from Erythritol-Producing Yeast Candida magnoliae

Yoo¹,

Park²,

Seo³

et al. 2014

Journal of Microbiology and Biotechnology

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The entire nucleotide sequence of the TKL1 gene encoding transketolase (TKL) in an erythritolproducing yeast of Candida magnoliae was determined by degenerate polymerase chain reaction and genome walking. Sequence analysis revealed an open reading frame of C. magnoliae TKL1 (CmTKL1) that spans 2,088 bp and encodes 696 amino acids, sharing 61.7% amino acid identity to Kluyveromyces lactis TKL. Functional analysis showed that CmTKL1 complemented a Saccharomyces cerevisiae tkl1 tkl2 double mutant for growth in the absence of aromatic amino acids and restored transketolase activity in this mutant. An enzyme activity assay and RT-PCR revealed that the expression of CmTKL1 is induced by fructose, H2O2, and KCl. The GenBank accession number for C. magnoliae TKL1 is KF751756.

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“…Because commercial supplies of D-X5P become limited, and because this compound is difficult to synthesize in a pure form (Zimmermann et al, 1999), similar multi-enzyme assays have been recently reported using systems able to generate this donor in situ . Other donor substrates have been investigated such as D-fructose-6-phosphate (D-F6P) (Naula et al, 2008) or L-erythrulose (L-ERY) (Hecquet et al, 1993). In these cases the released aldehydes, D-erythrose-4-phosphate (D-E4P) or glycolaldehyde (GA) respectively, are reduced by an NADH-dependent dehydrogenase.…”

Section: Introductionmentioning

confidence: 99%