Crystal Structures of Pyrophosphatase from Acinetobacter baumannii: Snapshots of Pyrophosphate Binding and Identification of a Phosphorylated Enzyme Intermediate.

摘要: All living things have pyrophosphatases that hydrolyze pyrophosphate and release energy. This energetically favorable reaction drives many unfavorable reactions. An accepted catalytic model of pyrophosphatase shows a water molecule activated by two divalent cations (M1 M2) within the center can attack in an SN2 mechanism thus molecule. However, our co-crystal structure Acinetobacter baumannii with from solvent may, fact, be actual water. In wild-type pyrophosphate, electron density centers each monomer are different one another. indicates pyrophosphates dynamic. Our mass spectroscopy results identified highly conserved lysine residue (Lys30) is phosphorylated, indicating enzyme could form phosphoryl intermediate during hydrolysis. Mutation Lys30 to Arg abolished activity enzyme. apo wild type enzyme, we observed Na+ ion coordinated residues loop proximal center. Therefore, mutated three key (K143R, P147G, K149R) determined K+-induced inhibition on their activities. Compared P147G most sensitive these cations, whereas K143R was inactive K149R showed no change activity. These data indicate monovalent play role down-regulating vivo. Overall, reveal new aspects catalysis assist design specific inhibitors growth.