Characterization of Bile Salt Hydrolase from Lactobacillus gasseri FR4 and Demonstration of Its Substrate Specificity and Inhibitory Mechanism Using Molecular Docking Analysis

Abstract

Probiotic bacteria are beneficial to the health of poultry animals, thus are used as alternative candidates for antibiotics used as growth promoters (AGPs). However, they also reduce the body weight gain due to innate bile salt hydrolase (BSH) activity. Hence, the addition of a suitable BSH inhibitor along with the probiotic feed can decrease the BSH activity. In this study, a BSH gene (981 bp) encoding 326-amino acids was identified from the genome of Lactobacillus gasseri FR4 (LgBSH). The LgBSH-encoding gene was cloned and purified using an Escherichia coli BL21 (DE3) expression system, and its molecular weight (37 kDa) was confirmed by SDS–PAGE and a Western blot analysis. LgBSH exhibited greater hydrolysis toward glyco-conjugated bile salts compared to tauro-conjugated bile salts. LgBSH displayed optimal activity at 52°C at a pH of 5.5, and activity was further increased by several reducing agents (DTT), surfactants (Triton X-100 and Tween 80), and organic solvents (isopropanol, butanol, and acetone). Riboflavin and penicillin V, respectively, inhibited LgBSH activity by 98.31 and 97.84%. A homology model of LgBSH was predicted using EfBSH (4WL3) as a template. Molecular docking analysis revealed that the glycocholic acid had lowest binding energy of -8.46 kcal/mol; on the other hand, inhibitors, i.e., riboflavin and penicillin V, had relatively higher binding energies of -6.25 and -7.38 kcal/mol, respectively. Our results suggest that L. gasseri FR4 along with riboflavin might be a potential alternative to AGPs for poultry animals.

Lactobacillus gasseri in the Upper Small Intestine Impacts an ACSL3-Dependent Fatty Acid-Sensing Pathway Regulating Whole-Body Glucose Homeostasis

“…Another urgent question is which bile acid(s) are involved in L. gasseri-induced FXR inhibition? L. gasseri preferentially deconjugates glyco-conjugated bile acids rather than tauro-conjugated bile acids (Rani et al, 2017), which would lead to a drop in glyco-conjugated bile acid with a relatively stable level of tauroconjugated bile acids. On one hand, deconjugation of glycoconjugated bile acids would result in increased excretion of these bile acids, as deconjugation increases the hydrophobicity of bile acids leading to increased excretion (Choi et al, 2015;Schiff et al, 1972).…”

“…This suggests that the increase in upper small intestinal L. gasseri could restore glucoregulatory fatty acid-sensing pathways and improve glucose control in these HFD transplanted rats. L. gasseri exhibits bile salt hydrolase activity (Rani et al, 2017), and administration of L. gasseri probiotics alters the bile acid pool and promotes bile acid excretion in rats (Usman and Hosono, 2001). In parallel, the bile acid sequestrant colesevelam improves glycemic control in diabetic humans (Beysen et al, 2012;Marina et al, 2012) and rodents (Prawitt et al, 2011;Trabelsi et al, 2015) and inhibits intestinal FXR in rodents (Prawitt et al, 2011;Trabelsi et al, 2015).…”

Bile salt hydrolases: Structure and function, substrate preference, and inhibitor development

“…Being located at the bottom of the binding pocket, Ile56 and Leu63 may determine the differing substrate preferences of LsB‐30514_BSH1. According to the results of molecular docking studies, Cys2 and Lys59 in the substrate‐binding pocket of LgFR4_BSH are found to form hydrogen bonds with GCA . Similarly, GDCA forms hydrogen‐bonding interactions with Cys2, Phe25, and Lys59, but Lys59 and Gln135 interact with TCA via hydrogen bonding.…”

“…When used at high concentrations, they can improve the growth performance and feed efficiency in swine and poultry . Some currently used AGPs such as penicillin V, ampicillin, doxycycline hydrochloride, and tetracycline also show significant inhibitory effects on BSH activities. However, long‐term use of these metal ions and antibiotics affects animal health, and increases the accumulation of metal ions in the treated animals and the environment as well as the risk of acquiring antibiotic‐resistant bacteria, respectively.…”

In vitro assessment of hypocholesterolemic activity of Lactococcus lactis subsp. lactis

“…Recently, several studies have been published on the distribution and activity of BSH in more than 300 lactic acid bacteria strains from the genera Bifidobacterium and Lactobacillus, and the species Lactococcus lactis, Leuconostoc mesenteroides, and Streptococcus thermophilus (González-Vázquez et al 2015;Xu et al 2016;Rani et al 2017). Lactobacillus spp.…”