Fructose 6-phosphate aldolase and 1-deoxy-d-xylulose 5-phosphate synthase from Escherichia coli as tools in enzymatic synthesis of 1-deoxysugars

We cloned the genes for a novel fructose 6-phosphate aldolase (FSA) and for 1-deoxy-d-xylulose 5-phosphate synthase (DXS) from Escherichia coli and investigated in their potential for enzymatic synthesis. FSA is the first example of a novel type of class I aldolases as it catalyzes the reversible formation of fructose 6-phosphate from dihydroxyacetone and d-glyceraldehyde 3-phosphate. It utilizes several aldehydes as acceptor compounds, and interestingly, hydroxyacetone is an alternative donor which can be used to generate 1-deoxysugars. DXS catalyzes the decarboxylation of pyruvate and transfers the covalently bound thiamin diphosphate-intermediate C2-moiety to d-glyceraldehyde 3-phosphate. The reaction product, 1-deoxy-d-xylulose 5-phosphate, is a precursor to isoprenoids and vitamins. DXS also uses other sugar phosphates as well as short aldehydes as acceptor substrates. Apart from pyruvate, the two α-ketoacids hydroxypyruvate and α-oxobutyrate could be used as donor substrates. FSA and DXS were successfully used to synthesize 1-deoxyketoses from C4 (1-deoxy-erythrulose) to C7 (1-deoxy-sedoheptulose) in phosphorylated and non-phosphorylated form.