Characterization of alkaline phosphatase PhoK from Sphingomonas sp. BSAR-1 for phosphate monoester synthesis and hydrolysis

Publication date: Available online 31 October 2019Source: Biochimica et Biophysica Acta (BBA) - Proteins and ProteomicsAuthor(s): Michael Lukesch, Gábor Tasnádi, Klaus Ditrich, Mélanie Hall, Kurt FaberAbstractThe biocatalytic activity of a so far underexploited alkaline phosphatase, PhoK from Sphingomonas sp. BSAR-1, was extensively studied in transphosphorylation and hydrolysis reactions. The use of high-energy phosphate donors and oligophosphates as suitable phosphate donor was evaluated, as well as the hydrolytic activity on a variety of phosphate monoesters. While substrates bearing free hydroxy group displayed only moderate reactivity as acceptors for transphosphorylation by PhoK, strong hydrolytic activity on a broad variety of phosphate monoesters under alkaline conditions was observed. Site-directed mutagenesis of selected amino acid residues in the active site provided valuable insights on their involvement in enzyme catalysis. The key residue Thr89 so far postulated to engage in enzyme phosphorylation was confirmed to be crucial for catalysis and could be replaced by serine, albeit with much lower catalytic efficiency.

Source: Biochimica et Biophysica Acta (BBA) Proteins and Proteomics - October 31, 2019 Category: Biochemistry Source Type: research