Demonstration of Substrate Specificity of Bile Salt hydrolase from Lactobacillus reuteri CRL 1098 Using Molecular Docking Analysis

BUSTOS, ANA; TARANTO, MARÍA; ANA LEDESMA

Congreso; XLVII Reunión Anual de la Sociedad Argentina de Biofísica; 2018

The microbial enzyme Bile Salt Hydrolase (BSH) releases free BA plus amino acid(taurine or glycine) from the Conjugated Bile Acids (BA). Currently, BSH inhibitors may become novel and attractive growth promoters. Detailed knowledge of BSH substrate preferences provide a solid foundation for rationally BSH inhibitor design. The aim of this work was to characterize the substrate specificity of BSH from Lactobacillus reuteri CRL 1098 using molecular docking analysis and DFT calculations. The deconjugation of both taurocholate and glycocholate optimized from Gaussian Program, was performed using AutoDock 4.2 tool with a semiempirical free-energy force. Our results showed that CRL 1098-BSH exhibited greater hydrolysis toward glyco-conjugated BA compared to tauro-conjugated ones. In fact, the molecular docking illustrated that both conjugated are embedded into binding pockets with the binding energy (BE) of ?7.31 and -5.72 kcal/mol, respectively, indicating an energetically favorable binding for glycoholate as compared to taurocholate. In addition, docking results indicate a polar or charged nature of the residues in the binding site in accordance with the five catalytically important amino acidsresidues (Cys, Asp, Asn, Asn, Arg) are highly conserved in CRL 1098 strain. Hydrogen bonding interaction can be observed between these residues within both taurocholate and glycocholate. The formation of less hydrogen bonds was observed in the interactions of taurocholate with BSH as compared to glycocholate, reflecting a lesser binding affinity between the ligand and receptor. All these correlated well with experimental data of glycocholate being more favorable to bind with BSH as compared to taurocholate. In this work we provide the molecular basis for substrate recognition of BSH from the probiotic CRL 1098 strain. These data could be useful for development of safe and cost effective BSH inhibitors as a replacement of current antibiotic growth promoters.