InterPro domain: IPR001585

Transaldolase ( 2.2.1.2 ) catalyses the reversible transfer of a three-carbon ketol unit from sedoheptulose 7-phosphate to glyceraldehyde 3-phosphate to form erythrose 4-phosphate and fructose 6-phosphate. This enzyme, together with transketolase, provides a link between the glycolytic and pentose-phosphate pathways. Transaldolase is an enzyme of about 34kDa whose sequence has been well conserved throughout evolution. A lysine has been implicated [ 1 ] in the catalytic mechanism of the enzyme; it acts as a nucleophilic group that attacks the carbonyl group of fructose-6-phosphate.

Transaldolase (TAL) is an enzyme of the pentose phosphate pathway (PPP) found almost ubiquitously in the three domains of life (Archaea, Bacteria, and Eukarya). TAL shares a high degree of structural similarity and sequence identity with fructose-6-phosphate aldolase (FSA) [ 2 ]. They both belong to the class I aldolase family [ 3 ]. Their protein structures have been revealed [ 4 ].

Fructose-6-phosphate aldolase was originally thought to be transaldolases or transaldolase-related proteins. However, they perform a novel reaction, the cleavage or formation of fructose 6-phosphate [ 5 ].

1. Lysine144 is essential for the catalytic activity of Saccharomyces cerevisiae transaldolase. Yeast 9, 1241-9
2. Fructose-6-phosphate aldolase is a novel class I aldolase from Escherichia coli and is related to a novel group of bacterial transaldolases. J. Biol. Chem. 276, 11055-61
3. Converting Transaldolase into Aldolase through Swapping of the Multifunctional Acid-Base Catalyst: Common and Divergent Catalytic Principles in F6P Aldolase and Transaldolase. Biochemistry 54, 4475-86
4. Sweet siblings with different faces: the mechanisms of FBP and F6P aldolase, transaldolase, transketolase and phosphoketolase revisited in light of recent structural data. Bioorg. Chem. 57, 263-80