Relationship of cytoarchitecture and glucose metabolism
Ovádi, J.1, Vértessy, B.G.1, Kovács, J.2, Orosz, F.1
1Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, H-1518 Budapest, Hungary
2Department of General Zoology, Faculty of Sciences, University of Eötvös, H-1445 Budapest, Hungary
Architecture of cytoplasm in eukaryotic cells is highly organized due to decoration of cytoskeletal network by cytosolic enzymes as well as transient formation of protein clusters within interstitial voids. Phosphofructokinase (PFK) displays considerable association to microtubule (MT) system with dual functions: on one hand, the tubules are periodically cross-bridged by PFK resulting in ultrastructure which is resistant against antimitotic agents, on the other hand, the bound PFK becomes inactive and resistant against proteolysis. These effects are highly specific to oligomers and isoforms. Specific metabolites modulate the association of the kinase to the single but not to the boundled tubules.Aldolase binding to MTs at near physiological ionic strength is weak as compared to that of the kinase. Their bindings to MT interfere with each other although they have distinct binding domains on MTs. While aldolase associates to Cterminal tails, kinase binds to MT "body", thus the binding does not interfere with that of MAPs. The mechanism responsible for this finding is that the two sequential enzymes form bienzyme complex in the solution which does not bind to MT. The bienzyme complex formation does not influence the catalytic activity of aldolase, however, it inhibits the dissociation- induced inactivation of the kinase by stabilizing the "nascently" formed active dimer. The present data suggest the first experimental evidence that two sequential glycolytic enzymes do not associate simultaneuosly to MTs but their complexation in the solution phase produces kinetic advantage for glycolysis. Molecular models for the microcompartmentation and the regulation in glycolysis have been evaluated.
| LOCATION |
DATE |
TIME |
| Lecture Hall II |
Monday, April 6 |
02:40 pm |