Biochemical and structural exploration of the catalytic capacity of Sulfolobus KDG aldolases

Suzanne Wolterink-van Loo (1) , André van Eerde , Marco A. J. Siemerink , Jasper Akerboom , Bauke W. Dijkstra , John van Der Oost

1 Agrotechnology and Food Sciences Group

Aldolases are enzymes with potential applications in biosynthesis, depending on their activity, specificity and stability. In this study, the genomes of Sulfolobus species were screened for aldolases. Two new 2-keto-3-deoxygluconate (KDG) aldolases from S. acidocaldarius and S. tokodaii were identified, overexpressed in E. coli, and characterised. Both enzymes were found to have biochemical properties similar to the previously characterized S. solfataricus KDG aldolase, including the condensation of pyruvate and either D,L-glyceraldehyde or D,L-glyceraldehyde-3-phosphate. The crystal structure of S. acidocaldarius KDG aldolase revealed the presence of a novel phosphate binding motif that allows the formation of multiple hydrogen bonding interactions with the acceptor substrate, and enables high activity with glyceraldehyde-3-phosphate. Activity analyses with unnatural substrates revealed that these three KDG aldolases readily accept aldehydes with 2-4 carbon atoms, and that even aldoses with 5 carbon atoms are accepted to some extent. Water-mediated interactions permit binding of substrates in multiple conformations in the spacious hydrophilic binding site, and correlate with the observed broad substrate specificity.

Mots clés: Life Sciences

Suzanne Wolterink-van Loo, André van Eerde, Marco A. J. Siemerink, Jasper Akerboom, Bauke W. Dijkstra, et al.. Biochemical and structural exploration of the catalytic capacity of Sulfolobus KDG aldolases. Biochemical Journal, 2006, 403 (3), pp.421-430. ⟨10.1042/BJ20061419⟩. ⟨hal-00478665⟩