Crystallization and preliminary X-ray analysis of a lipase from Bacillus subtilis.

Single crystals of the lipase from Bacillus subtilis have been obtained using a mixture of polyethylene glycol 4000 and sodium sulphate solution as the precipitant. The crystals grow at room temperature in two to three weeks in the presence of n-octyl-beta-D-glucoside. They belong to the monoclinic space group C2 with a = 121.20 A, b = 93.19 A, c = 80.96 A, and beta = 110.67 degrees, with four protein molecules per asymmetric unit. The crystals diffract to at least 2.5 A resolution and are suitable for an X-ray structure analysis.

The structure-function relationship of the lipases from Pseudomonas aeruginosa and Bacillus subtilis.

Within the BRIDGE T-project on lipases we investigate the structure-function relationships of the lipases from Bacillus subtilis and Pseudomonas aeruginosa. Construction of an overproducing Bacillus strain allowed the purification of > 100 mg lipase from 30 l culture supernatant. After testing a large variety of crystallization conditions, the Bacillus lipase gave crystals of reasonable quality in PEG-4000 (38-45%), Na2SO4 and octyl-beta-glucoside at 22 degrees C, pH 9.0. A 2.5 A dataset has been obtained which is complete from 15 to 2.5 A resolution. P.aeruginosa wild-type strain PAC1R was fermented using conditions of maximum lipase production. More than 90% of the lipase was cell bound and could be solubilized by treatment of the cells with Triton X-100. This permitted the purification of approximately 50 mg lipase. So far, no crystals of sufficient quality were obtained. Comparison of the model we built for the Pseudomonas lipase, on the basis of sequences and structures of various hydrolases which were found to possess a common folding pattern (alpha/beta hydrolase fold), with the X-ray structure of the P.glumae lipase revealed that it is possible to correctly build the structure of the core of a protein even in the absence of obvious sequence homology with a protein of known 3-D structure.

Purification and preliminary characterization of the extracellular lipase of Bacillus subtilis 168, an extremely basic pH-tolerant enzyme.

The extracellular lipase of Bacillus subtilis 168 was purified from the growth medium of an overproducing strain by ammonium sulfate precipitation followed by phenyl-Sepharose and hydroxyapatite column chromatography. The purified lipase had a strong tendency to aggregate. It exhibited a molecular mass of 19,000 Da by SDS-PAGE and a pI of 9.9 by chromatofocusing. The enzyme showed maximum stability at pH 12 and maximum activity at pH 10. The lipase was active toward p-nitrophenyl esters and triacylglycerides with a marked preference for esters with C8 acyl groups. Using trioleyl glycerol as substrate, the enzyme preferentially cleaved the 1(3)-position ester bond. No interfacial activation effect was observed with triacetyl glycerol as substrate.

Cloning, nucleotide sequence and expression in Escherichia coli of a lipase gene from Bacillus subtilis 168.

The gene coding for an extracellular lipase of Bacillus subtilis 168 was cloned and found to be expressed in Escherichia coli. Enzyme activity measurements showed no fatty acid chain length preference. A set of Tn5 insertions which inactivate the gene were localized and used to initiate its sequencing. The nucleotide sequence was determined on two independent clones expressed in E. coli. In one of these clones, the sequence revealed a frameshift, due to the presence of an additional adenine in the N-terminal region, which caused the interruption of the open reading frame, probably allowing translation to initiate at a second ATG codon. The sequence of the wild-type lip gene from B. subtilis was confirmed on the chromosomal fragment amplified by polymerase chain reaction (PCR). When compared to other lipases sequenced to date, the enzyme described here lacks the conserved pentapeptide Gly-X-Ser-X-Gly supposed to be essential for catalysis. However, alignments of several microbial lipase sequences suggest that the pentapeptide Ala-X-Ser-X-Gly present in the lipase B. subtilis may function as the catalytic site. Homologies were found in the N-terminal protein region with lipases from different Pseudomonas species. The predicted M(r) and isoelectric point for the mature protein are 19,348 and 9.7 respectively.