Cloning, expression and characterization of a halotolerant esterase from a marine bacterium Pelagibacterium halotolerans B2T

An esterase PE10 (279 aa) from B2(T) was cloned and overexpressed in Rosetta in a soluble form. The deduced protein was 29.91 kDa and the phylogenetic analysis of the deduced amino acids sequence showed it represented a new family of lipolytic enzymes. The recombinant protein was purified by Ni-NTA affinity chromatography column and the characterization showed its optimal temperature and pH were 45 A degrees C and pH 7.5, respectively. Substrate specificity study showed PE10 preferred short chain -nitrophenyl esters and exhibited maximum activity toward -nitrophenyl acetate. In addition, PE10 was a halotolerant esterase as it was still active under 4 M NaCl. Three-dimensional modeling of PE10 suggested that the high negative electrostatic potential on the surface may relevant to its tolerance to high salt environment. With this halotolerance property, PE10 could be a candidate for industrial use.