Theoretical study of interactions between muscle aldolase and F-actin: insight into different species

Interactions of the glycolytic enzyme, fructose-1,6-bisphosphate aldolase (aldolase), with F-actin may be one mechanism for the colocalization of glycolytic enzymes. Examination of these interactions in different animal species tests this hypothesis by observing whether binding sites are conserved across species. Brownian dynamics (BD) simulations provide descriptions of such protein-protein interactions with the muscle isoforms of zebra fish and human aldolase. The results are compared with previous results obtained for rabbit muscle and yeast. The aldolase binding groove previously determined in rabbit muscle is conserved in both the human and fish muscle isoforms. The nonspecific radial free energies of interaction are similar with fish being slightly weaker than human and rabbit: human, -2.27 +/- 0.05 kcal/mol; rabbit, -2.0 +/- 0.04 kcal/mol; and fish, -1.5 +/- 0.03 kcal/mol. BD results show a large Boltzmann population of complexes formed around the A/D and B/C grooves of aldolase with the most feasible binding mode comprising two aldolase subunits to subdomain I region of the actin subunits. These results show that the location of the important residues and binding site for fish and human aldolase is very similar to that in rabbit and that in different animals the binding site is conserved. This suggests that the binding interaction between aldolase and F-actin is general in animal muscles and is rendered possible and energetically favorable through the conservation of this binding site.