C-Terminal Peptide of Fusarium heterosporum Lipase Is Necessary for Its Increasing Thermostability

Abstract

Saccharomyces cerevisiae bearing a lipase eDNA from Fusarium heterosporum produced two lipases, A and B. Lipase B was significantly more stable to temperature than lipase A, but their optimum temperatures were similar. Lipase B was composed of one polypeptide (301 amino acids), and lipase A was composed of two polypeptides (275 and 26 amino acids) generated by the cleavage between Arg 275 and Asp 276 with a trypsin-like protease. It was suggested that the C-terminal peptide (26 amino acids) tightened the lipase structure when bound to the catalytic domain (275 amino acids) through a peptide bond. The tight structure was loosened by cleavage of the C-terminal peptide, even though the peptide interacted noncovalently with the catalytic domain, possibly through charged amino acids, in which it is rich. Deletion of the C-terminal peptide greatly decreased the lipase production by the recombinant S. cerevisiae, although its transcriptional level was the same as that of cells carrying the wild-type gene. These facts suggested that the C-terminal peptide affected the lipase production in the post-transcriptional step.