Schenk, Gerhard and Layfield, Roy and Candy, Judith M. and Duggleby, Ronald G. and Nixon, Peter F. (1997) Molecular Evolutionary Analysis of the Thiamine-Diphosphate-Dependent Enzyme, Transketolase. Journal of Molecular Evolution , 44. pp. 552-572. ISSN 0022-2844

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Abstract

Members of the transketolase group of thiamine- diphosphate-dependent enzymes from 17 different organisms including mammals, yeast, bacteria, and plants have been used for phylogenetic reconstruction. Alignment of the amino acid and DNA sequences for 21 transketolase enzymes and one putative transketolase reveals a number of highly conserved regions and invariant residues that are of predicted importance for enzyme activity, based on the crystal structure of yeast transketolase. One particular sequence of 36 residues has some similarities to the nucleotide-binding motif and we designate it as the transketolase motif. We report further evidence that the recP protein from Streptococcus pneumoniae might be a transketolase and we list a number of invariant residues which might be involved in substrate binding. Phylogenies derived from the nucleotide and the amino acid sequences by various methods show a conventional clustering for mammalian, plant, and gramnegative bacterial transketolases. The branching order of the gram-positive bacteria could not be inferred reliably. The formaldehyde transketolase (sometimes known as dihydroxyacetone synthase) of the yeast Hansenula polymorpha appears to be orthologous to the mammalian enzymes but paralogous to the other yeast transketolases. The occurrence of more than one transketolase gene in some organisms is consistent with several gene duplications. The high degree of similarity in functionally important residues and the fact that the same kinetic mechanism is applicable to all characterized transketolase enzymes is consistent with the proposition that they are all derived from one common ancestral gene. Transketolase appears to be an ancient enzyme that has evolved slowly and might serve as a model for a molecular clock, at least within the mammalian clade.

Item Type:	Article
Keywords:	Transketolase; Thiamine diphosphate; Transketolase motif; Evolution; Phylogenetic trees; Molecular clock;
Academic Unit:	Faculty of Science and Engineering > Chemistry
Item ID:	3746
Depositing User:	Gary Schenk
Date Deposited:	07 Jun 2012 15:39
Journal or Publication Title:	Journal of Molecular Evolution
Publisher:	Springer Verlag
Refereed:	Yes
URI:
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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