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Title: Biochemical characterization of the initial steps of the Kennedy pathway in Trypanosoma brucei : the ethanolamine and choline kinases
Authors: Gibellini, Federica
Hunter, William N.
Smith, Terry K.
Keywords: Choline kinase
Ethanolamine kinase
Kennedy pathway
Trypanosoma brucei
African sleeping sickness
Saccharomyces-cerevisiae
glycosylphosphatidylinositol
Caenorhabditis-elegans
Drug target
Phosphatidylethanolamine
Donor
Purification
Specificity
Expression
QH301 Biology
QD Chemistry
Issue Date: 1-Oct-2008
Citation: Gibellini , F , Hunter , W N & Smith , T K 2008 , ' Biochemical characterization of the initial steps of the Kennedy pathway in Trypanosoma brucei : the ethanolamine and choline kinases ' Biochemical Journal , vol 415 , no. 1 , pp. 135-144 .
Abstract: Ethanolamine and choline are major components of the trypanosome membrane phospholipids, in the form of GPEtn (glycero-phosphoethanolamine) and GPCho (glycerophosphocholine). Ethanolamine is also found as an integral component of the GPI (glycosylpliosphatidylinositol) anchor that is required for membrane attachment of cell-surface proteins, most notably the variant-surface glycoproteins. The de novo synthesis of GPEtn and GPCho starts with the generation of phosphoethanolamine and phosphocholine by ethanolamine and choline kinases via the Kennedy pathway. Database mining revealed two putative C/EKs (choline/ethanolamine kinases) in the Trypanosoma brucei genome, which were cloned, overexpressed, purified and characterized. TbEK 1 (T brucei ethanolamine kinase 1) was shown to be catalytically active as an ethanolamine-specific kinase, i.e. it had no choline kinase activity. The K values for ethanolamine and ATP were found to be 18.4 +/- 0.9 and 219 29 mu M respectively. TbC/EK2 (T brucei choline/ethanolamine kinase 2), on the other hand, was found to be able to phosphorylate both ethanolamine and choline, even though choline was the preferred substrate, with a K-m 80 times lower than that of ethanolamine. The K. values for choline, ethanolamine and ATP were 31.4 +/- 2.6 mu M, 2.56 +/- 0.31 mu M and 20.6 +/- 1.96 mu M respectively. Further substrate specificity analysis revealed that both TbEK1 and TbC/EK2 were able to tolerate various modifications at the amino group, with the exception of a quaternary amine for TbEK1 (choline) and a primary amine for TbC/EK2 (ethanolamine). Both enzymes recognized analogues with substituents oil C-2, but substitutions oil C-1 and elongations of the carbon chain were not well tolerated.
Version: Publisher PDF
Description: Note related output below contains correction of this paper.
Status: Peer reviewed
URI: http://hdl.handle.net/10023/2086
DOI: http://dx.doi.org/10.1042/BJ20080435
ISSN: 0264-6021
Type: Journal article
Rights: © 2008 The Author(s) The author(s) has paid for this article to be freely available under the terms of the Creative Commons Attribution Non-Commercial Licence (http://creativecommons.org/licenses/by-nc/2.5/) which permits unrestricted non-commercial use, distribution and reproduction in any medium, provided the original work is properly cited.
Appears in Collections:University of St Andrews Research
Biology Research
Biomedical Sciences Research Complex (BSRC) Research



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