Details

Autor(en) / Beteiligte

• Jin, Yi
• Bhattasali, Debabrata
• Pellegrini, Erika
• get, Stephanie M
• Baxter, Nicola J
• Cliff, Matthew J
• Bowler, Matthew W
• Jakeman, David L
• Blackburn, G Michael
• Waltho, Jonathan P

Titel

[alpha]-Fluorophosphonates reveal how a phosphomutase conserves transition state conformation over hexose recognition in its two-step reaction

Ist Teil von

• Proceedings of the National Academy of Sciences - PNAS, 2014-08, Vol.111 (34), p.12384

Ort / Verlag

Washington: National Academy of Sciences

Erscheinungsjahr

2014

Quelle

EZB Free E-Journals

Beschreibungen/Notizen

• β-Phosphoglucomutase (βPGM) catalyzes isomerization of β-d-glucose 1-phosphate (βG1P) into d-glucose 6-phosphate (G6P) via sequential phosphoryl transfer steps using a β-d-glucose 1,6-bisphosphate (βG16BP) intermediate. Synthetic fluoromethylenephosphonate and methylenephosphonate analogs of βG1P deliver novel step 1 transition state analog (TSA) complexes for βPGM, incorporating trifluoromagnesate and tetrafluoroaluminate surrogates of the phosphoryl group. Within an invariant protein conformation, the β-d-glucopyranose ring in the βG1P TSA complexes (step 1) is flipped over and shifted relative to the G6P TSA complexes (step 2). Its equatorial hydroxyl groups are hydrogen-bonded directly to the enzyme rather than indirectly via water molecules as in step 2. The (C)O-P bond orientation for binding the phosphate in the inert phosphate site differs by ~30° between steps 1 and 2. By contrast, the orientations for the axial O-Mg-O alignment for the TSA of the phosphoryl group in the catalytic site differ by only ~5°, and the atoms representing the five phosphorus-bonded oxygens in the two transition states (TSs) are virtually superimposable. The conformation of βG16BP in step 1 does not fit into the same invariant active site for step 2 by simple positional interchange of the phosphates: the TS alignment is achieved by conformational change of the hexose rather than the protein.