Characterization of a Novel GDSL Esterase/Lipase (Itbgdsl_2) from Pseudoxanthomonas taiwanensis
Abstract
ITBGDSL_2 from Pseudoxanthomonas taiwanensis was cloned, expressed and characterized. The enzyme showed high homology to putative GDSL esterase/lipase from Lysobacteraceae bacterium (98.99%) and 40.21% similarity to cloned of lysophospholipase from an uncultured bacterium. Homologycal analysis to the previously crystallized enzymes, including the GDSL esterase from Pseudoalteromonas sp. (PDB ID: 3HP4) and the lysophospholipase from Pseudomonas aeruginosa (PDB ID: 4JGG) showed that Itbgdsl_2 is significantly different from the other enzymes, despite the enzyme contained all conserved motifs as the GDSL esterase family. Further analysis by comparing the sequence of Itbgdsl_1 and Itbgdsl_2 showed that both enzyme are completely different on the three dimensional structure and intramolecular interaction. Biochemical characterization of Itbgdsl_2 demonstrated its capability to hydrolysis ester substrates with optimal activity toward p-nitrophenyl acetate at pH 7 and 55 °C. The enzyme showed single band at ± 27 kDa on SDS-PAGE electrophoresis following purification using Ni-NTA chromatography. The activity of Itbgdsl_2 was decreased by the addition of metal ions, detergents, and specific inhibitors. The enzyme also displayed thermostability, remaining stable for up to 12 hours at 55 °C. All of the results showed that Itbgdsl_2 might a novel member of the GDSL enzyme family and potential as industrial biocatalyst.
