Download MendeleyPeri active site catalysis of proline isomerisation is the molecular basis of allomorphy in beta-phosphoglucomutase.
Cruz-Navarrete, F.A., Baxter, N.J., Flinders, A.J., Buzoianu, A., Cliff, M.J., Baker, P.J., Waltho, J.P.(2024) Commun Biol 7: 909-909
- PubMed: 39068257
- DOI: https://doi.org/10.1038/s42003-024-06577-9
- Primary Citation of Related Structures:
8Q1C, 8Q1D, 8Q1E, 8Q1F - PubMed Abstract:
Metabolic regulation occurs through precise control of enzyme activity. Allomorphy is a post-translational fine control mechanism where the catalytic rate is governed by a conformational switch that shifts the enzyme population between forms with different activities. β-Phosphoglucomutase (βPGM) uses allomorphy in the catalysis of isomerisation of β-glucose 1-phosphate to glucose 6-phosphate via β-glucose 1,6-bisphosphate. Herein, we describe structural and biophysical approaches to reveal its allomorphic regulatory mechanism. Binding of the full allomorphic activator β-glucose 1,6-bisphosphate stimulates enzyme closure, progressing through NAC I and NAC III conformers. Prior to phosphoryl transfer, loops positioned on the cap and core domains are brought into close proximity, modulating the environment of a key proline residue. Hence accelerated isomerisation, likely via a twisted anti/C4-endo transition state, leads to the rapid predominance of active cis-P βPGM. In contrast, binding of the partial allomorphic activator fructose 1,6-bisphosphate arrests βPGM at a NAC I conformation and phosphoryl transfer to both cis-P βPGM and trans-P βPGM occurs slowly. Thus, allomorphy allows a rapid response to changes in food supply while not otherwise impacting substantially on levels of important metabolites.
Organizational Affiliation:
School of Biosciences, University of Sheffield, Sheffield, S10 2TN, UK.
