All 4 bile salt hydrolase proteins are responsible for the hydrolysis activity in Lactobacillus plantarum ST-III

In vertebrates, bile salt hydrolysis plays an essential role in fat metabolism. Bile salts are synthesized in the liver. And in the small intestine glycine and taurine are de-conjugated from bile salts by the enzyme bile salt hydrolase (BSH) from intestinal microbes. However, the mechanism of bile salt hydrolysis in Lactobacillus plantarum is still ambiguous. Four predicted bile salt hydrolase (bsh) genes from L. plantarum ST-III were cloned into Escherichia coli. The function of these genes was explored by overexpression. All 4 proteins that were studied showed activity against glycine- or taurine-conjugated bile salts. Substrate preference was also observed in BSH proteins, especially for the enzyme BSH1, which had high hydrolysis activity for glycodeoxycholic acid. These results suggest that all 4 bile salt hydrolases may be responsible for the bile salt hydrolysis activity in L. plantarum ST-III. PRACTICAL APPLICATION: Hypercholesterolemia is considered one of the major risk factors for coronary heart disease. More interest has focused on intestinal microbes because of their role in the decrease of serum cholesterol. BSH proteins play an important role in the reduction of cholesterol. This paper adds to a better understanding of BSH proteins of intestinal microbes. It gives a great hint that probiotics can be used to solve hypercholesterolemia one day.