Abstract
Simultaneous binding of two sequential glycolytic enzymes, phosphofructokinase and aldolase, to a microtubular network was investigated. The binding of the phosphofructokinase to microtubules and its bundling activity has been previously characterized (Lehotzky, A., Telegdi, M., Liliom, K., and Ovádi, J. (1993) J. Biol. Chem. 268, 10888-10894). Aldolase binding to microtubules at near physiological ionic strength is weak (Kd = 20 microM) as compared with that of the kinase (Kd = 1 microM). The interactions of both enzymes with microtubules are modulated by their common intermediate, fructose-1,6-bisphosphate. Pelleting and electron microscopic measurements have revealed that the aldolase binding interferes with that of phosphofructokinase, although they have distinct binding domains on microtubules. The underlying molecular mechanism responsible for this finding is that in the solution phase aldolase and phosphofructokinase form a bienzyme complex that does not bind to the microtubule. The bienzyme complex formation does not influence the catalytic activity of aldolase, however, it inhibits the dissociation-induced inactivation of the kinase by stabilizing a catalytically active molecular form. The present data suggest the first experimental evidence that two sequential glycolytic enzymes do not associate simultaneously to microtubules, but their complexation in solution provides kinetic advantage for glycolysis.
Highlights
Simultaneous binding of two sequential glycolytic enzymes, phosphofructokinase and aldolase, to a microtubular network was investigated
The bienzyme complex formation does not influence the catalytic activity of aldolase, it inhibits the dissociation-induced inactivation of the kinase by stabilizing a catalytically active molecular form
1-phosphofructokinase (PFK) with its comparatively low isoelectric point [7] does not associate to the carboxyl-terminal tubulin tails, but it associates to the MT “body” and periodically cross-bridges single microtubules at physiological ionic strength [8]
Summary
Simultaneous binding of two sequential glycolytic enzymes, phosphofructokinase and aldolase, to a microtubular network was investigated. The present data suggest the first experimental evidence that two sequential glycolytic enzymes do not associate simultaneously to microtubules, but their complexation in solution provides kinetic advantage for glycolysis. Kinetic Experiments and Activity Assays—1 M PFK and different concentrations of aldolase were incubated with or without 10 M taxolstabilized MT for 30 min at 30 °C in standard buffer.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
