The cloning and characterization of one novel metagenome-derived thermostable esterase acting on N-acylhomoserine lactones

摘要

A novel gene (designated as est816) encoding an esterase was isolated from a Turban Basin metagenomic library with a functional screening method. Sequence analysis revealed that est816 encoded a protein of 271 amino acids with a predicted molecular mass (Mr) of 29.9 kDa and was expressed in Escherichia coli BL21 (DE3) in soluble form. The optimum pH and temperature of the recombinant Est816 were 7.5 and 60 °C, respectively, the enzyme was stable in the pH range of 5.0-9.0 and at temperatures below 50 °C The residual activity of Est816 was 47.7% when stored at 25 °C for 5 months. The enzyme could hydrolyze a wide range of p-nitrophenyl esters, but its best substrate is p-nitrophenyl acetate with the highest activity (364U/mg). It could also degrade medium to long-chain AHLs at the concentration of 1 mM in half an hour with more than 90% degradation efficiency. This is the first report to construct one metagenomic library from Turban Basin to obtain one esterase, which belongs to family V esterases/lipases and has AHL-lactonase activity. The recombinant enzyme displayed broad substrate spectrum, high activity and thermostability. These excellent properties make it an attractive enzyme for quorum quenching.