Biochemical Characterization of a Novel Thermostable Esterase from the Metagenome of Dokdo Islets Marine Sediment
2017
Lee, C.M., National Institute of Agricultural Sciences, Rural Development Administration, Jeonju, Republic of Korea | Seo, S., Global R and D Center, ISU ABXIS, Seongnam, Republic of Korea | Kim, S.Y., National Institute of Agricultural Sciences, Rural Development Administration, Jeonju, Republic of Korea | Song, J., National Institute of Agricultural Sciences, Rural Development Administration, Jeonju, Republic of Korea | Sim, J.S., National Institute of Agricultural Sciences, Rural Development Administration, Jeonju, Republic of Korea | Hahn, B.S., National Institute of Agricultural Sciences, Rural Development Administration, Jeonju, Republic of Korea | Kim, D.H., National Institute of Agricultural Sciences, Rural Development Administration, Jeonju, Republic of Korea | Yoon, S.H., National Institute of Agricultural Sciences, Rural Development Administration, Jeonju, Republic of Korea
A functional screen of 60,672 fosmid metagenomic clones amplified from marine sediment obtained from the Dokdo islets in Korea identified the gene EstES1, whose product, EstES1, displayed lipolytic properties on tributyrin-supplemented media. EstES1 is a 576 amino acid protein with a predicted molecular weight of 59.4 kDa including 37 N-terminal leader amino acids. EstES1 exhibited the highest sequence similarity (44%) to a carboxylesterase found in Haliangium ochraceum DSM14365. Phylogenetic analysis indicated that EstES1 belongs to a currently uncharacterized family of lipases. Within the conserved domain, EstES1 retains the catalytic triad that consists of the consensus penta-peptide motif, GESAG. EstES1 demonstrated a broad substrate specificity toward the long acyl group of ethyl esters (C2 - C12), and its optimal activity was recorded toward p-Nitrophenyl butyrate (C4) at pH 9.0 and 40℃ (specific activity of 255.4 U/mg). The enzyme remained stable in the ranges of 60 - 65℃ and pH 9.0-10.5 and in the presence of methanol, ethanol, isopropanol, and dimethyl sulfoxide. Therefore, EstES1 has potential for use in industrial applications involving high temperature, organic solvents, and/or alkaline conditions.
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