In contrast to this conventional concept, archaeal fructose-1,6-bisphosphate (FBP) aldolase/phosphatase (FBPA/P) consists of a single catalytic domain, but catalyses two chemically distinct reactions of gluconeogenesis: (1) the reversible aldol condensation of dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (GA3P) to FBP; (2) the dephosphorylation of FBP to fructose-6-phosphate (F6P)2. Thus, FBPA/P is fundamentally different from ordinary enzymes whose active sites are responsible for a specific reaction. However, the molecular mechanism by which FBPA/P achieves its unusual bifunctionality remains unknown. Here we report the crystal structure of FBPA/P at 1.5-Å resolution in the aldolase form, where a critical lysine residue forms a Schiff base with DHAP. A structural comparison of the aldolase form with a previously determined phosphatase form3 revealed a dramatic conformational change in the active site, demonstrating that FBPA/P metamorphoses its active-site architecture to exhibit dual activities. Thus, our findings expand the conventional concept that one enzyme catalyses one biochemical reaction.
Jing, please don't copy the paper abstract verbatim. Re-write to express your own view/opinion. For example, I don't understand how this paper is relevant to material we have covered in class?
ReplyDeleteI came across a related paper that came out around the same time, "Active-site remodelling in the bifunctional fructose-1,6-bisphosphate aldolase/phosphatase".
ReplyDeletehttp://www.nature.com/nature/journal/vaop/ncurrent/full/nature10458.html?WT.ec_id=NATURE-20111013
They use structural information to look at active site conformation changes that lead to the different catalytic activities of the enzyme. If people are interested in the bi-functionality of this enzyme this paper is worth looking at.