title: Structural and functional analysis of a conjugated bile salt hydrolase from Bifidobacterium longum reveals an evolutionary relationship with penicillin V acylase.
abstract: Bile salt hydrolase (BSH) is an enzyme produced by the intestinal microflora that catalyzes the deconjugation of glycine- or taurine-linked bile salts. The crystal structure of BSH reported here from Bifidobacterium longum reveals that it is a member of N-terminal nucleophil hydrolase structural superfamily possessing the characteristic alphabetabetaalpha tetra-lamellar tertiary structure arrangement. Site-directed mutagenesis of the catalytic nucleophil residue, however, shows that it has no role in zymogen processing into its corresponding active form. Substrate specificity was studied using Michaelis-Menten and inhibition kinetics and fluorescence spectroscopy. These data were compared with the specificity profile of BSH from Clostridium perfrigens and pencillin V acylase from Bacillus sphaericus, for both of which the three-dimensional structures are available. Comparative analysis shows a gradation in activity toward common substrates, throwing light on a possible common route toward the evolution of pencillin V acylase and BSH.
authors.affiliation: Division of Biochemical Sciences, National Chemical Laboratory, Pune 411 008, India.
authors.forename: R Suresh
authors.initials: RS
authors.lastname: Kumar
authors.forename: James A
authors.initials: JA
authors.lastname: Brannigan
authors.forename: Asmita A
authors.initials: AA
authors.lastname: Prabhune
authors.forename: Archana V
authors.initials: AV
authors.lastname: Pundle
authors.forename: Guy G
authors.initials: GG
authors.lastname: Dodson
authors.forename: Eleanor J
authors.initials: EJ
authors.lastname: Dodson
authors.forename: C G
authors.initials: CG
authors.lastname: Suresh
mesh_terms: D000581:Amidohydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D001644:Bifidobacterium / Q000201:enzymology*; D001665:Binding Sites; D003016:Clostridium perfringens / Q000201:enzymology; D018360:Crystallography, X-Ray; D019281:Dimerization; D019143:Evolution, Molecular; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D016297:Mutagenesis, Site-Directed; D010399:Penicillin Amidase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D017386:Sequence Homology, Amino Acid; D013050:Spectrometry, Fluorescence; D055672:Static Electricity; D013379:Substrate Specificity
chemical_list: D000581:Amidohydrolases; D010399:Penicillin Amidase; C023154:choloylglycine hydrolase