Associations of glycolytic enzymes with the cytoskeleton
Bereiter-Hahn, J., Schindler, R., Blum, S., Airas, J., Mittal, A.K.
Cinematic Cell Research Group, Biocentre, Johann Wolfgang Goethe Universität,
Frankfurt am Main, Germany
In living non-muscle cells cytoskeletal fibres provide a huge surface for binding a large variety of molecules including water, metabolites, ions and proteins. The glycolytic enzymes aldolase and glyceraldehyde-phosphate - dehydrogenase (GAP-DH) belong to the most abundant enzymes found in many cells and at least a part of these enzymes is associated with cytoskeletal elements. The molar fraction of the enzymes exceeds that of their respective substrates by a factor of about 10. This is a clear indication for glycolysis running far from equilibrium conditions at high enzyme and low substrate concentrations, just the opposite situation than that being described by Michaelis - Menten kinetics. The binding of glycolytic complexes to F-actin can accelerate substrate turnover about 10-fold at sub-micromolar substrate concentrations in vitro while no significant effect is exerted at millimolar concentrations. One reason for this difference may be the substrate dependence of the enzyme-cytoskeleton association. Fluorescence - resonance - energy - transfer (FRET) is an elegant method to demonstrate associations of proteins with each other and can be used to show the shift of bound aldolase to F-actin in absence of substrate to G-actin and other cytoskeletal proteins at millimolar concentrations of its substrate fructose-bisphosphate. In situ (in living or permeabilised cells) the supply of energy consuming processes as are actin polymerisation at the leading edge of a moving cell or contractions of the cytoplasmic actomyosin fibrillar network seems to be provided by glycolysis as is shown using immunofluorescent staining and observing cell motility under different regimes of enzyme inhibition including the use of desoxyglucose, oxamic acid and antimycin.
| LOCATION |
DATE |
TIME |
| Lecture Hall II |
Monday, April 6 |
03:30 pm |