Cloning and expression of an endopeptidase gene from Lactobacillus helveticus CM4 involved in processing antihypertensive peptides.

A gene corresponding to an endopeptidase was cloned and sequenced from Lactobacillus helveticus CM4. Sequence analysis revealed similarity between the cloned gene and the pepO gene previously reported from L. helveticus CNRZ32. The strain designated as Escherichia coli CM4-EP, which was transformed with the endopeptidase gene from L. helveticus CM4, expressed endopeptidase activity capable of releasing the antihypertensive peptides Val-Pro-Pro from Val-Pro-Pro-Phe-Leu and lle-Pro-Pro from lle-Pro-Pro-Leu-Thr. The pepO gene product had similar characteristics to an endopeptidase previously purified from L. helveticus CM4. Moreover, the endopeptidase activity expressed in E. coli CM4-EP was completely inhibited by the addition of antibody raised against the purified endopeptidase from L. helveticus CM4. These results suggest that the gene cloned from L. helveticus CM4 in this study might be the pepO gene and the gene product might play an important role in processing antihypertensive peptides in L. helveticus fermentation.