4z74

Crystal structure of inorganic pyrophosphatase from Mycobacterium tuberculosis in complex with inorganic pyrophosphate

spinqualitylabelsall models 4z74, resolution 2.55Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4z74 is a 12 chain structure. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CA, POP Related: 4z70, 4z71, 4z72, 4z73 Activity: Inorganic diphosphatase, with EC number 3.6.1.1 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum Publication Abstract from PubMed Family I inorganic pyrophosphatases (PPiases) are ubiquitous enzymes that are critical for phosphate metabolism in all domains of life. The detailed catalytic mechanism of these enzymes, including the identity of the general base, is not fully understood. We determined a series of crystal structures of the PPiase from Mycobacterium tuberculosis (Mtb PPiase) bound to catalytic metals, inorganic pyrophosphate (PPi; the reaction substrate) and to one or two inorganic phosphate ions (Pi; the reaction product), ranging in resolution from 1.85 to 3.30A. These structures represent a set of major kinetic intermediates in the catalytic turnover pathway for this enzyme and suggest an order of association and dissociation of the divalent metals, the substrate and the two products during the catalytic turnover. The active site of Mtb PPiase exhibits significant structural differences from the well characterized Escherichia coli PPiase in the vicinity of the bound PPi substrate. Prompted by these differences, quantum mechanics/molecular mechanics (QM/MM) analysis yielded an atomic description of the hydrolysis step for Mtb PPiase and, unexpectedly, indicated that Asp89, rather than Asp54 that was proposed for E. coli PPiase, can abstract a proton from a water molecule to activate it for a nucleophilic attack on the PPi substrate. Mutagenesis studies of the key Asp residues of Mtb PPiase supported this mechanism. This combination of structural and computational analyses clarifies our understanding of the mechanism of family I PPiases and has potential utility for rational development of drugs targeting this enzyme. Structural and computational dissection of the catalytic mechanism of the inorganic pyrophosphatase from Mycobacterium tuberculosis.,Pratt AC, Dewage SW, Pang AH, Biswas T, Barnard-Britson S, Cisneros GA, Tsodikov OV J Struct Biol. 2015 Aug 19. pii: S1047-8477(15)30048-4. doi:, 10.1016/j.jsb.2015.08.010. PMID:26296329 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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