Identification and characterization of a novel salt‐tolerant esterase from a Tibetan glacier metagenomic library

Abstract

A salt-tolerant esterase, designated H9Est, was identified from a metagenomic library of the Karuola glacier. H9Est gene comprised 1071 bp and encoded a polypeptide of 357 amino acids with a molecular mass of 40 kDa. Sequence analysis revealed that H9Est belonged to the family IV of bacterial lypolitic enzyme. H9Est was overexpressed in Escherichia coli and the purified enzyme showed hydrolytic activity towards p-nitrophenyl esters with carbon chain from 2 to 8. The optimal esterase activity was at 40°C and pH 8.0 and the enzyme retained its activity towards some miscible organic solvents such as polyethylene glycol. A three-dimensional model of H9Est revealed that S200, D294, and H324 formed the H9Est catalytic triad. Circular Dichroism spectra and molecular dynamic simulation indicated that the esterase had a wide denaturation temperature range and flexible loops that would be beneficial for H9Est performance at low temperatures while retaining heat-resistant features.

Improvement of the halotolerance of a Bacillus serine protease by protein surface engineering

“…[37] The halotolerant esterases, H9Est esterase (KF994924, pI = 8.67) and H8 esterase (KY273927, pI = 9.09), with many basic amino acid residues on their protein surface and alkaline pIs, have been isolated via metagenomics and characterized. [38,39] More than 10 homologous sequences with similar basic/acidic residue ratios and predicted pI values (7.96-10.28) to H8 can be found in the NCBI nr database. [39] In mAla-8, 36 Asp, 97 Asp, and 251 Glu were substituted with Ala (Figure S1), and the number of basic amino acid residues and Arg and Lys residues located on the protein surface were unchanged.…”

Characterization of a novel marine microbial esterase and its use to make D-methyl lactate

“…PHE14 was also characterized to be a salt-tolerant microbial esterase. Some other esterases such as EstKT4, EstKT7, and EstKT9 from the tidal flat sediments of Ganghwa Island in South Korea kept 40%, 10% and 40% of their initial activity in the presence of 4 mol/L NaCl [22][23][24].…”

Metagenomic Approaches as a Tool to Unravel Promising Biocatalysts from Natural Resources: Soil and Water

“…In addition to aquatic sediments, other types of samples with metagenomic exploitation potential come from arid/semiarid and mountain soils, for example in the Ladakh region [70] and the Apharwat mountain [41,44], respectively, both in the northwestern Himalayas that have distinct geo-climatic characteristics like extremely cold and dry weather, high altitude and glacial and permafrost soils. Relevant examples of this are the Karuola glacier in Tibetan Plateau [45] and the Kolyma Lowland permafrost in north-eastern Siberia [47], which are extremely hostile environments and inhabited by unique microbial communities.…”