Isolation and analysis of a gene from the marine microalga Isochrysis galbana that encodes a lipase-like protein

Abstract : Microalgae constitute a novel study area for characterising new lipolytic enzymes of biotechnological interest. A new gene from the microalga Isochrysis galbana has been isolated and a preliminary characterisation performed. The full-length cDNA contains 2,060 base pairs with an open reading frame of 1,374 nucleotides encoding a polypeptide of 457 amino acids with a predicted molecular mass of 49 kDa, and a theoretical pI of 5.65. The deduced protein includes highly conserved motifs found in alpha/beta fold hydrolases, and shares some similarities with putative or known lipases. Sequence comparison indicated that the catalytic triad corresponds to residues Ser(188), Asp(306) and His(391), with the nucleophilic residue Ser(188) positioned within the consensus G-X-S-188-X-G pentapeptide. Phylogenetic analyses established close relationships with fungal lipases and microalgal sequences.