Potential Allosteric Sites Captured in Glycolytic Enzymes via
Residue-Based Network Models: Phosphofructokinase,
Glyceraldehyde-3-Phosphate Dehydrogenase and Pyruvate Kinase
Abstract
Likelihood of new allosteric sites for glycolytic enzymes,
phosphofructokinase (PFK), glyceraldehyde-3-phosphate dehydrogenase
(GADPH) and pyruvate kinase (PK) was evaluated for bacterial, parasitic
and human species. Allosteric effect of a ligand binding at a site was
revealed on the basis of low-frequency normal modes via Cα-harmonic
residue network model. In bacterial PFK, perturbation of the proposed
allosteric site outperformed the known allosteric one, producing a high
amount of stabilization or reduced dynamics, on all catalytic regions.
Another proposed allosteric spot at the dimer interface in parasitic PFK
exhibited major stabilization effect on catalytic regions. In parasitic
GADPH, the most desired allosteric response was observed upon
perturbation of its tunnel region which incorporated key residues for
functional regulation. Proposed allosteric site in bacterial PK produced
a satisfactory allosteric response on all catalytic regions, whereas in
human and parasitic PKs, a partial inhibition was observed. Residue
network model based solely on contact topology identified the ‘hub
residues’ with high betweenness tracing plausible allosteric
communication pathways between distant functional sites. For both
bacterial PFK and PK, proposed sites accommodated hub residues twice as
much as the known allosteric one. Tunnel region in parasitic GADPH with
the strongest allosteric effect among species, incorporated the highest
number of hub residues. These results clearly suggest one-to-one
correspondence between the degree of allosteric effect and the number of
hub residues in that perturbation site, which increases the likelihood
of its allosteric nature.