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KMID : 0545120120220091245
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Journal of Microbiology and Biotechnology
2012 Volume.22 No. 9 p.1245 ~ p.1252
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Gene Cloning and Characterization of a Cold-Adapted Esterase from Acinetobacter venetianus V28
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Kim Young-Ok
Heo Yu-Li
Kim Hyung-Kwoun
Nam Bo-Hye
Kong Hee-Jeong
Kim Dong-Gyun
Kim Woo-Jin
Kim Bong-Seok
Jee Young-Ju
Lee Sang-Jun
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Abstract
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Acinetobacter venetians V28 was isolated from the intestine of righteye flounder, Poecilopsetta plinthus caught in Vietnam seawater, and the esterase gene was cloned using a shotgun method. The amino acid sequence deduced from the nucleotide sequence (1,017 bp) corresponded to a protein of 338 amino acid residues with a molecular weight of 37,186. The esterase had 87% and 72% identities with the lipases of A. junii SH205 and A. calcoaceticus RUH2202, respectively. The esterase contained a putative leader sequence, as well as the conserved catalytic triad (Ser, His, Asp), consensus pentapeptide GXSXG, and oxyanion hole sequence (HG). The protein from the strain V28 was produced in both a soluble and an insoluble form when the Escherichia coli cells harboring the gene were cultured at 18oC. The maximal activity of the purified enzyme was observed at a temperature of 40oC and pH 9.0 using p-NP-caprylate as substrate; however, relative activity still reached to 70% even at 5oC with an activation energy of 3.36 kcal/mol, which indicated that it was a cold-adapted enzyme. The enzyme was a nonmetalloprotein and was active against p-nitrophenyl esters of C4, C8, and C14. Remarkably, this enzyme retained much of its activity in the presence of commercial detergents and organic solvents. This cold-adapted esterase will be applicable as catalysts for reaction in the presence of organic solvents and detergents.
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KEYWORD
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Acinetobacter sp., cold-adapted esterase, gene expression, activation energy
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