Dimer interface rearrangement of the 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase rat liver isoenzyme by cAMP-dependent Ser-32 phosphorylation

The bifunctional enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2/FBPase-2) is a key regulator of carbohydrate metabolism in liver. The goal of this study was to elucidate the regulatory role of Ser-32 phosphorylation on the kinase domain mediated dimerization of PFK-2/FBPase-2. Fluorescence-based mammalian two-hybrid and sensitized emission fluorescence resonance energy transfer analyses in cells revealed preferential binding within homodimers in contrast to heterodimers. Using isolated proteins a close proximity of two PFK-2/FBPase-2 monomers was only detectable in the phosphorylated enzyme dimer. Thus, a flexible kinase interaction mode exists, suggesting dimer conformation mediated coupling of hormonal and posttranslational enzyme regulation to the metabolic response in liver.Structured summary of protein interactionsPFK-2/FBPase-2physically interacts with PFK-2/FBPase-2 by fluorescent resonance energy transfer (View Interaction: 1, 2)PFK-2/FBPase-2physically interacts with PFK-2/FBPase-2 by two hybrid (View interaction)

► Ser-32 phosphorylation reciprocally modulates the activities of liver PFK-2/FBPase-2.
► Dimerization of PFK-2/FBPase-2 was analyzed by fluorescence-based assays.
► Preferentially two Ser-32 phosphorylated PFK-2/FBPase-2 proteins interact.
► Conformational changes of PFK-2/FBPase-2 are crucial for the metabolic response in liver.