A thermophilic hormone-sensitive lipase family esterase Est1404 identified from an Antarctic bacterium Pseudomonas sp. E2-15

Esterases are a group of enzymes with a diverse range of uses in industry. We identified a novel hormone-sensitive lipase (HSL) in the esterase family, Est1404, through cloning and expression from the Antarctic bacterium Pseudomonas sp. E2–15, from soil collected on King George Island. Investigations showed that the Est1404 enzyme is a thermophilic esterase that maintains 90–100% activity throughout the temperature range of 60–90 °C. It exhibits the highest catalytic activity towards p-nitrophenol butyrate at 70 °C and pH 8.5. Est1404 was inhibited by the serine-modifying reagent phenylmethylsulfonyl fluoride, but thiol reagents such as dithiolthreitol stimulated its activity. Metal chelating chemicals, such as ethylenediaminetetraacetic acid, did not affect its activity. Phylogenetic analysis indicated that Est1404 is in the GDSAG subfamily of HSL. The enzyme contains a GDSAG motif with an active serine (S) positioned within a catalytic triad consisting of highly conserved Ser156, Asp250 and His280 residues. The thermal stability of the Est1404 esterase makes it potentially useful in industrial catalysis.