A Method for Purification of Clostridium perfringens Phospholipase C from Recombinant Bacillus subtilis Cells

High-level expression of clostridial sialidase using a ferredoxin gene promoter-based plasmid

A "large" sialidase isozyme (NanI) from Clostridium perfringens is a representative microbial sialidase with broad substrate specificity, being used for the analysis of sialoglycoconjugates. It is also a possible virulence factor. However, purification of the native enzyme in a large quantity is not practical due to its low productivity. To obtain the enzyme in a satisfactory yield, a gene encoding the NanI was transcriptionally fused to the fdx gene promoter (P(fdx)) in a shuttle-vector, pFF, and transformed into C. perfringens 13. The resultant strain released the enzyme into the culture medium, as the original strain does. The enzyme activity increased during the first 6 h of culture and thereafter remained at maximal levels. The maximal activity was approximately 3000-fold compared with that of the original strain, and 15-fold compared with that of recombinant Escherichia coli, which possesses extra copies of the tRNA gene for selected rare codons. This suggests the usefulness of a P(fdx)-based plasmid for expressing AT-rich genes in C. perfringens. The enzyme was successfully purified by two-step procedure with a specific activity of 2860 U/mg using 2'-(4-methylumbelliferyl)-alpha-D-N-acetylneuraminic acid and a yield of 1.69 mg of NanI per 100 ml of culture. The method described here can facilitate purification of NanI in enough quality and quantity to analyze the role of sialoglycoconjugates in cells and the pathogenic importance of NanI sialidase.

Production and purification of Clostridium perfringens alpha-toxin using a protein-hyperproducing strain, Bacillus brevis 47

Clostridium perfringens alpha-toxin was produced in a protein-hyperproducing strain, Bacillus brevis 47, by cloning the gene into the constructed expression-secretion vector which has the multiple promoters and the signal peptide coding region of an outer cell wall protein gene. The amount of alpha-toxin produced by the B. brevis 47 transformant carrying the gene was approximately 10 times greater than that produced by a B. subtilis transformant carrying the toxin gene. Biological activities and the N-terminal amino acid sequence of the toxin secreted by the B. brevis 47 transformant were identical to those of wild-type alpha-toxin.

Expression of the colH gene encoding Clostridium histolyticum collagenase in Bacillus subtilis and its application to enzyme purification

The colH gene encoding 116-kDa collagenase of Clostridium histolyticum (cColH) was cloned into an Escherichia coli-Bacillus subtilis shuttle vector to develop a method for purification of recombinant collagenase (rColH). When plasmid pJCM310 containing the colH gene was introduced into B. subtilis DB104 and the transformant was grown in LB broth at 37 C, stability of the plasmid was not maintained. However, stability was partly improved by growing the transformant in a modified LB broth containing 0.5 M sodium succinate with gentle shaking at 35 C. When the transformant was grown to an optical density of 0.4 at 600 nm in this medium, pJCM310 was stable and rColH was produced in sufficient amounts. rColH was purified to homogeneity by ammonium sulfate precipitation, gel filtration and ion-exchange chromatography. The yield of rColH from an 800-ml culture was 0.53 mg and its specific activity was estimated to be 1,210 U per mg of protein. The purified rColH was capable of degrading native type-I collagen fibril from bovine achilles tendon, as was demonstrated by zymography. A comparison of the N-terminal amino acid sequence between cColH and rColH revealed that rColH has 10 extra N-terminal amino acid residues. However, the peptide mapping of rColH with V8 protease was virtually identical to that of cColH. Furthermore, the molecular mass of rColH was estimated to be 112,999 Da by mass spectrometry, coinciding with the value of 112,977 Da, which was predicted from the nucleotide sequence of the colH gene. Therefore, the recombinant B. subtilis culture is capable of serving as a useful source for enzyme purification.