Lipase and its modulator from Pseudomonas sp strain KFCC 10818: Proline-to-glutamine substitution at position 112 induces formation of enzymatically active lipase in the absence of the modulator

A lipase gene, lipK, and a lipase modulator gene, limK, of Pseudomonas sp. strain KFCC 10818 have been cloned, sequenced, and expressed in Escherichia coli. The limK gene is located immediately downstream of the lipK gene. En zymatically active lipase was produced only in the presence of the limK gen e. The effect of the lipase modulator LimK on the expression of active lipa se was similar to those of the Pseudomonas subfamily I.1 and I.2 lipase-spe cific foldases (Lifs). The deduced amino acid sequence of LimK shares low h omology (17 to 19%) with the known Pseudomonas Lifs, suggesting that Pseudo monas sp. strain KFCC 10818 is only distantly related to the subfamily I.1 and I.2 Pseudomonas species. Surprisingly, a lipase variant that does not r equire LimK for its correct folding was isolated in the study to investigat e the functional interaction between LipK and LimK. When expressed in the a bsence of LimK, the P112Q variant of LipK formed an active enzyme and displ ayed 63% of the activity of wild-type LipK expressed in the presence of Lim K. These results suggest that the Pro(112) residue of LipK is involved in a key step of lipase folding. We expect that the novel finding of this study may contribute to future research on efficient expression or refolding of industrially important lipases and on the mechanism of lipase folding.