title: Biochemical and structural exploration of the catalytic capacity of Sulfolobus KDG aldolases.
abstract: Aldolases are enzymes with potential applications in biosynthesis, depending on their activity, specificity and stability. In the present study, the genomes of Sulfolobus species were screened for aldolases. Two new KDGA [2-keto-3-deoxygluconate (2-oxo-3-deoxygluconate) aldolases] from Sulfolobus acidocaldarius and Sulfolobus tokodaii were identified, overexpressed in Escherichia coli and characterized. Both enzymes were found to have biochemical properties similar to the previously characterized S. solfataricus KDGA, including the condensation of pyruvate and either D,L-glyceraldehyde or D,L-glyceraldehyde 3-phosphate. The crystal structure of S. acidocaldarius KDGA 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 KDGAs readily accept aldehydes with two to four carbon atoms, and that even aldoses with five 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.
authors.affiliation: Laboratory of Microbiology, Wageningen University, 6703 CT Wageningen, The Netherlands. suzanne.vanloo@wur.nl
authors.forename: Suzanne
authors.initials: S
authors.lastname: Wolterink-van Loo
authors.forename: André
authors.initials: A
authors.lastname: van Eerde
authors.forename: Marco A J
authors.initials: MA
authors.lastname: Siemerink
authors.forename: Jasper
authors.initials: J
authors.lastname: Akerboom
authors.forename: Bauke W
authors.initials: BW
authors.lastname: Dijkstra
authors.forename: John
authors.initials: J
authors.lastname: van der Oost
mesh_terms: D000446:Aldehyde-Lyases / Q000737:chemistry* / Q000378:metabolism*; D000447:Aldehydes / Q000378:metabolism; D001665:Binding Sites; D003001:Cloning, Molecular; D003460:Crystallization; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000378:metabolism; D008958:Models, Molecular; D011773:Pyruvates / Q000378:metabolism; D013379:Substrate Specificity; D016944:Sulfolobus / Q000201:enzymology*
chemical_list: D000447:Aldehydes; D011773:Pyruvates; D000446:Aldehyde-Lyases; C021468:2-keto-3-deoxy-D-glucarate aldolase