Transketolase gene

Ikeda, M., Okamoto, K., and Katsumata, R. (1999) Cloning of the transketolase gene and the effect of its dosage on aromatic amino acid production in Corynebacterium glutamicum. Appl. Microbiol. Biotechnol, 51 (2), 201-206. 

Transketolase (EC 2.2.1.1), which catalyses condensations between aldehydes and hydroxypyiuvic acid with loss of CO2 (see Vol. 25, Chapter 2, Ref. 9) has been produced in relatively large quantities from an over-expressed E. coli transformant carrying the transketolase gene. This enzynte was fairly non-specific with respect to the aldehyde component, although best results were achieved with a-hydroxyaldehydes. ... 

Sprenger, G.A. et al.. Identification of a thiamin-dependent synthase in Escherichia coli required for the formation of the 1-deoxy-D-xylulose 5-phosphate precursor to isoprenoids, thiamin, and pyridoxol, Proc. Natl. Acad Sci. USA 94, 12857, 1997. Lange, B.M. et al., A family of transketolases that directs isoprenoid biosynthesis via a mevalonate-independent pathway, Proc. Natl. Acad Sci. USA 95, 2100, 1998. Lois, L.M. et al., Cloning and characterization of a gene from Escherichia coli encoding a transketolase-like enzyme that catalyzes the synthesis of D-1- deoxyxylulose 5-phosphate, a common precursor for isoprenoid, thiamin, and pyridoxol biosynthesis, Proc. Natl. Acad. Sci. USA 95, 2105, 1998. 

TALDO deficiency can be confirmed in lymphoblasts, fibroblasts and in erythrocytes. These cells are incubated with ribose-5-phosphate, after which formation of transketolase and TALDO products are analysed by gas chromatography with nitrogen phosphorous detection by liquid chromatography tandem mass spectrometry [8, 11]. A similar enzyme assay is available for RPI [2]. Confirmation of the gene defect can be performed by sequence analysis. Disease-causing mutations have been detected in all TALDO-deficient patients and in the RPI-deficient patient. 

In humans with Wernicke-Korsakoff syndrome, a mutation in the gene for transketolase results in... 

LM Lois, N Campos, SR Putra, K Danielsen, M Rohmer, A Boronat. Cloning and characterization of a gene from Escherichia coli encoding a transketolase-like enzyme that catalyzes the synthesis of D-l-deoxyxylulose 5-phosphate, a common precursor for isoprenoid, thiamin, and pyridoxol biosynthesis. Proc Natl Acad Sci (USA) 95 2105-2110, 1998. 

In a very imaginative piece of research Frost and coworkers have developed a plasmid-based method for synthesizing aromatic amino acids, by incorporating the genes that code for the enzymes that perform the series of conversions from D-fructose-6-phosphate to D-erythrose-4-phosphate to 3-deoxy-D-arabinoheptulosonic acid-7-phos-phate (DAHP) near each other on a plasmid that can be transformed in E. coli. The enzymes are the thiamin diphosphate-dependent enzyme transketolase in the nonoxida-tive pentose shunt and DAHP synthase. The DAHP is then converted to the cyclic dehydroquinate, a precursor to all aromatic amino acids L-Tyr, L-Phe and L-Trp165,166 (equation 27). 

J.F. Coy, S. Dubel, P. Kioschis, K. Thomas, G. Micklem, H. Delius, and A. Poustka. 1996. Molecular cloning of tissue-specific transcripts of a transketolase-related gene Implications for the evolution of new vertebrate genes Genomics 32 309-316. (PubMed)... 

Transcription factors, 50, 399,444,592 gene activaticm, 588-590 Transferrin, 741-742, 755, 756 Transferrin infCeptOr, 50, 755 Transfer RNA, set tRNA Transketolase, 604,607 Translation, 36-37,38 0, 748,826-827 Transport systems, amino acids, 89 TRH (thyrotiiopin-releasing barmone), 735 Tricarboxylic acid cycle, 228 TrigJyfieridEs... 

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