Identification and characterisation of LIP7 and LIP8 genes encoding two extracellular triacylglycerol lipases in the yeast Yarrowia lipolytica

Abstract

In the lipolytic yeast Yarrowia lipolytica, the LIP2 gene was previously reported to encode an extracellular lipase. The growth of a Δ lip2 strain on triglycerides as sole carbon source suggest an alternative pathway for triglycerides utilisation in this yeast. Here, we describe the isolation and the characterisation of the LIP7 and LIP8 genes which were found to encode a 366 and a 371-amino acid precursor protein, respectively. These proteins which belong to the triacylglycerol hydrolase family (EC 3.1.1.3) presented a high homology with the extracellular lipase Cd LIP2 and Cd LIP3 from Candida deformans. The physiological function of the lipase isoenzymes was investigated by creating single and multi-disrupted strains. Lip7p and Lip8p were found to correspond to active secreted lipases. The lack of lipase production in a Δ lip2 Δ lip7 Δ lip8 strain suggest that no additional extracellular lipase remains to be discovered in Y. lipolytica. The substrate specificity towards synthetic ester molecules indicates that Lip7p presented a maximum activity centred on caproate (C 6) while that of Lip8p is in caprate (C 10).