Cloning, expression and characterization of a novel esterase from a South China Sea sediment metagenome

Lipolytic enzymes, including esterases and lipases, represent a group of hydrolases that catalyze the cleavage and formation of ester bonds. A novel esterase gene, scsEst01, was cloned from a South China Sea sediment metagenome. The scsEst01 gene consisted of 921 bp encoding 307 amino acid residues. The predicted amino acid sequence shared less than 90% identity with other lipolytic enzymes in the NCBI nonredundant protein database. ScsEst01 was successfully co-expressed in Escherichia coli BL21 (DE3) with chaperones (dnaK-dnaJ-grpE) to prevent the formation of inclusion bodies. The recombinant protein was purified on an immobilized metal ion affinity column containing chelating Sepharose charged with Ni2+. The enzyme was characterized using p -nitrophenol butyrate as a substrate. ScsEst01 had the highest lipolytic activity at 35A degrees C and pH 8.0, indicative of a meso-thermophilic alkaline esterase. ScsEst01 was thermostable at 20A degrees C. The lipolytic activity of scsEst01 was strongly increased by Fe2+, Mn2+ and 1% Tween 80 or Tween 20.