TKL2, a second transketolase gene of Saccharomyces cerevisiae. Cloning, sequence and deletion analysis of the gene

Eur J Biochem. 1993 Oct 1;217(1):487-92. doi: 10.1111/j.1432-1033.1993.tb18268.x.


Transketolase activity is indispensable for the generation of erythrose 4-phosphate and therefore necessary for the biosynthesis of the aromatic amino acids. Yeast mutants with a deletion of the transketolase gene, TKL1, can grow without aromatic amino acid supplement indicating an additional source of erythrose 4-phosphate in the cells. Here we describe the cloning of TKL2, a gene coding for a second transketolase enzyme in Saccharomyces cerevisiae. The deduced protein sequence of TKL2 demonstrates 71% identity with TKL1 [Sundström, M., Lindqvist, Y., Schneider, G., Hellman, U. & Ronne, H. (1993) J. Biol. Chem., in the press]. Double mutants for both genes, TKL1 and TKL2, are auxotrophic for aromatic amino acids, indicating a complete block in the transketolase activity. Deletion of TKL2 alone does not lead to a significant phenotype, and transketolase activity is not reduced in these mutants. Overexpression of TKL2 on a multi-copy plasmid in a tkl1 background showed that TKL2 is functionally expressed: transketolase enzyme activity was detectable in the transformants and the protein reacts with anti-transketolase serum in Western blot analysis. In addition, transformation of the tkl1 tkl2 double mutant with the TKL2 plasmid can compensate the growth defect on a medium without aromatic amino acids.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Blotting, Western
  • Cloning, Molecular*
  • Gene Deletion*
  • Gene Expression
  • Genes, Fungal*
  • Molecular Sequence Data
  • Mutagenesis
  • Restriction Mapping
  • Saccharomyces cerevisiae / enzymology
  • Saccharomyces cerevisiae / genetics*
  • Sequence Analysis*
  • Transformation, Genetic
  • Transketolase / chemistry
  • Transketolase / genetics*


  • Transketolase

Associated data

  • GENBANK/L04514
  • GENBANK/L04515
  • GENBANK/L04516
  • GENBANK/L04517
  • GENBANK/X73532
  • GENBANK/X78993
  • GENBANK/Z25880
  • GENBANK/Z25881
  • GENBANK/Z25882
  • GENBANK/Z25883