Regulatory properties of potato-Arabidopsis hybrid ADP-glucose pyrophosphorylase.

In higher plants, ADP-glucose pyrophosphorylase (ADPGlc-PPase) is a heterotetrameric enzyme comprised of two small and two large subunits. Potato-Arabidopsis hybrid ADPGlc-PPases were generated and their regulatory properties analyzed. We show that ADPGlc-PPase subunits from two different species can interact, producing active enzymes with new regulatory properties. Depending on the subunit combinations, hybrid heterotetramers showed responses to allosteric effectors [3-phosphoglycerate (3-PGA) and Pi] in the micromolar or millimolar range. While hybrid potato small subunit (PSS) and the Arabidopsis large subunit APL1 showed an extremely sensitive response to 3-PGA and Pi, hybrid PSS/Arabidopsis APL2 was very insensitive to them. Intermediate responses were determined for other subunit combinations.