title: Yeast TKL1 gene encodes a transketolase that is required for efficient glycolysis and biosynthesis of aromatic amino acids.
abstract: A gene encoding transketolase, TKL1, was cloned from the budding yeast Saccharomyces cerevisiae using oligonucleotide primers derived from protein sequence data. The TKL1 sequence predicts a 74-kDa polypeptide which is related to other transketolases. A sequence comparison revealed that the transketolases can be subdivided into three evolutionary branches. We also found that the transketolases are related to another vitamin B1-dependent enzyme: the E1 subunit of pyruvate dehydrogenase from Escherichia coli. Gene disruption and overexpression experiments were used to investigate the function of transketolase in yeast. We found that growth on fermentable carbon sources, but not on gluconeogenic carbon sources, is reduced in cells disrupted for TKL1. This suggests that the glycolytic efficiency is impaired. Growth on fermentable carbon sources is also reduced in cells that overexpress TKL1. Finally, we found that cells disrupted for TKL1 are unable to grow in the absence of aromatic amino acids. This is most likely due to the fact that transketolase is required for the synthesis of erythrose-4-P, a precursor of the aromatic amino acids.
authors.affiliation: Department Molecular Biology, Swedish University of Agricultural Science, Uppsala Biomedical Center.
authors.forename: M
authors.initials: M
authors.lastname: Sundström
authors.forename: Y
authors.initials: Y
authors.lastname: Lindqvist
authors.forename: G
authors.initials: G
authors.lastname: Schneider
authors.forename: U
authors.initials: U
authors.lastname: Hellman
authors.forename: H
authors.initials: H
authors.lastname: Ronne
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000096:biosynthesis*; D001483:Base Sequence; D002244:Carbon / Q000378:metabolism; D003001:Cloning, Molecular; D005285:Fermentation; D005656:Fungal Proteins / Q000235:genetics*; D006019:Glycolysis; D006801:Humans; D008969:Molecular Sequence Data; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D014174:Transketolase / Q000235:genetics*
chemical_list: D000596:Amino Acids; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; D002244:Carbon; C084088:TKL1 protein, S cerevisiae; D014174:Transketolase