3M8Y

Phosphopentomutase from Bacillus cereus after glucose-1,6-bisphosphate activation

Summary for 3M8Y

• Entry DOI: 10.2210/pdb3m8y/pdb
• Related: 3M8Y 3M8Z 3M90
• Descriptor: Phosphopentomutase, MANGANESE (II) ION, ACETATE ION, ... (6 entities in total)
• Functional Keywords: alkaline phosphatase like core domain, di-metallo catalytic center, manganese binding, isomerase, manganese, metal-binding
• Biological source: Bacillus cereus
• Total number of polymer chains: 3
• Total formula weight: 135415.37

Authors

Panosian, T.D.,Nannemann, D.P.,Watkins, G.,Wadzinski, B.,Bachmann, B.O.,Iverson, T.M. (deposition date: 2010-03-19, release date: 2010-12-29, Last modification date: 2024-10-30)

Primary citation

Panosian, T.D.,Nannemann, D.P.,Watkins, G.R.,Phelan, V.V.,McDonald, W.H.,Wadzinski, B.E.,Bachmann, B.O.,Iverson, T.M.
Bacillus cereus Phosphopentomutase Is an Alkaline Phosphatase Family Member That Exhibits an Altered Entry Point into the Catalytic Cycle.
J.Biol.Chem., 286:8043-8054, 2011

PubMed Abstract: Bacterial phosphopentomutases (PPMs) are alkaline phosphatase superfamily members that interconvert α-D-ribose 5-phosphate (ribose 5-phosphate) and α-D-ribose 1-phosphate (ribose 1-phosphate). We investigated the reaction mechanism of Bacillus cereus PPM using a combination of structural and biochemical studies. Four high resolution crystal structures of B. cereus PPM revealed the active site architecture, identified binding sites for the substrate ribose 5-phosphate and the activator α-D-glucose 1,6-bisphosphate (glucose 1,6-bisphosphate), and demonstrated that glucose 1,6-bisphosphate increased phosphorylation of the active site residue Thr-85. The phosphorylation of Thr-85 was confirmed by Western and mass spectroscopic analyses. Biochemical assays identified Mn(2+)-dependent enzyme turnover and demonstrated that glucose 1,6-bisphosphate treatment increases enzyme activity. These results suggest that protein phosphorylation activates the enzyme, which supports an intermolecular transferase mechanism. We confirmed intermolecular phosphoryl transfer using an isotope relay assay in which PPM reactions containing mixtures of ribose 5-[(18)O(3)]phosphate and [U-(13)C(5)]ribose 5-phosphate were analyzed by mass spectrometry. This intermolecular phosphoryl transfer is seemingly counter to what is anticipated from phosphomutases employing a general alkaline phosphatase reaction mechanism, which are reported to catalyze intramolecular phosphoryl transfer. However, the two mechanisms may be reconciled if substrate encounters the enzyme at a different point in the catalytic cycle.

PubMed: 21193409
DOI: 10.1074/jbc.M110.201350

Experimental method

X-RAY DIFFRACTION (2.1 Å)