Redesign of the Phosphate Binding Site of L-Rhamnulose-1-Phosphate Aldolase towards a Dihydroxyacetone Dependent Aldolase

The aldol addition of unphosphorylated dihydroxyacetone (DHA) to aldehydes catalyzed by L-rhamnulose-1-phosphate aldolase (RhuA), a dihydroxyacetone phosphate-dependent aldolase, is reported. Moreover, a single point mutation in the phosphate binding site of the RhuA wild type, that is, substitution of aspartate for asparagine at position N29, increased by 3-fold the V-max(app) of aldol addition reactions of DHA to other aldehyde acceptors rather than the natural L-lactaldehyde. The RhuA N29D mutant modified the optimum enzyme design for the natural substrate and changed its catalytic properties making the aldolase more versatile to other aldol additions of DHA.