A low-M-r lipase activation factor cooperating with lipase modulator protein LimL in Pseudomonas sp strain 109

Pseudomonas sp, strain 109 produces a unique lipase (LipL) which efficientl y catalyses intramolecular transesterification of omega-hydroxyesters to fo rm macrocyclic lactones. in vivo production of enzymically active LipL requ ires lipase modulator protein (LimL), which functions as a molecular chaper one for the correct folding of LipL. However, previous work has shown that LipL forms a tight complex with LimL in vitro and the resulting LipL-LimL c omplex is only partially active, suggesting an additional mechanism that fa cilitates the dissociation of the complex to form enzymically active LipL. In the present work, a low-M-r compound (lipase activation factor, LAF) was found in Pseudomonas sp. strain 109 that when added to the LipL-LimL compl ex resulted in the activation of LipL. Ca2+ ions also enhanced lipase activ ity, but the instantaneous activation by Ca2+ was different from the gradua l and time-dependent activation by LAF, indicating the novel nature of this compound. LAF passed through an ultrafiltration membrane with an M-r cut-o ff of 3000 and showed an apparent M-r of 330+/-30 on Superdex Peptide gel-f iltration chromatography. Treatment of the LipL-LimL complex with LAF liber ated free active LipL, indicating that LAF was necessary to dissociate the LipL-LimL complex.