CALCIUM ION-DEPENDENT REACTIVATION OF A PSEUDOMONAS LIPASE BY ITS SPECIFIC MODULATING PROTEIN, LIPB

LipB, the lipase activator protein of Pseudomonas aeruginosa TE3285, w as overproduced in Escherichia coli, and purified 4.9-fold over the cr ude extract in the presence of SDS, The purified LipB reactivated the lipase from P. aeruginosa TE3285 denatured with guanidine hydrochlorid e, and its reactivation did not involve multiple turnover, In this rea ctivation, a 1:1 complex between the lipase and LipB was detected in a cross-linking experiment, suggesting that LipB still binds to the lip ase after the reactivation. Calcium ion was essential for the complex formation and the reactivation, and addition of EDTA caused inactivati on of the reactivated lipase bound to LipB more rapidly than the nativ e lipase, These findings suggest that LipB could affect the calcium bi nding to the lipase in the reactivation process, LipB was unable to re activate lipases from other sources except Pseudomonas sp, 109; this l ipase has an amino acid sequence which is 98% identical to that of the lipase from P. aeruginosa TE3285, Thus, it may be concluded that LipB specifically recognizes a unique structural element of the lipase.