Kerviel_2014_J.Appl.Phycol_26_2019

An ester hydrolase gene from the microalga Isochrysis galbana was cloned and expressed in Escherichia coli BL21 Rosetta 2. The full-length putative gene has 1,146 base pairs and codes for a 381-amino acid polypeptide. The predicted molecular mass of the deduced protein is approximately 42.31 kDa, with a theoretical pI of 9.37. Slight similarity and identity were observed between the microalga sequence and various alpha/beta-fold hydrolases found in diverse phyla. The catalytic triad corresponds to residues Ser254, Asp309, and His341, with the nucleophilic catalytic residue Ser254 located in the pentapeptide consensus motif G-X-S254-X-G. The activity of the enzyme was established by fatty acid profile analysis of the membrane lipids. The expression of the protein in E. coli shifted the fatty acid composition predominantly towards C16:1 and C18:1 fatty acids. This enzyme is called I. galbana thioesterase/carboxylesterase (or IgTeCe). This novel gene is shown to have a potential for use in metabolic engineering to enhance the lipid yields of microalgae.