Structural and functional analysis of a bile salt hydrolase from the bison microbiome.

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  • Additional Information
    • Source:
      Publisher: Elsevier Inc. on behalf of American Society for Biochemistry and Molecular Biology Country of Publication: United States NLM ID: 2985121R Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1083-351X (Electronic) Linking ISSN: 00219258 NLM ISO Abbreviation: J Biol Chem Subsets: MEDLINE
    • Publication Information:
      Publication: 2021- : [New York, NY] : Elsevier Inc. on behalf of American Society for Biochemistry and Molecular Biology
      Original Publication: Baltimore, MD : American Society for Biochemistry and Molecular Biology
    • Subject Terms:
      Amidohydrolases*/metabolism ; Amidohydrolases*/chemistry ; Amidohydrolases*/antagonists & inhibitors ; Bison*; Animals ; Arthrobacter/enzymology ; Microbiota ; Bacterial Proteins/chemistry ; Bacterial Proteins/metabolism ; Bacterial Proteins/genetics ; Bile Acids and Salts/metabolism ; Bile Acids and Salts/chemistry ; Kinetics ; Substrate Specificity ; Crystallography, X-Ray ; Catalytic Domain
    • Abstract:
      The bile salt hydrolases (BSHs) are significant constituents of animal microbiomes. An evolving appreciation of their roles in health and disease has established them as targets of pharmacological inhibition. These bacterial enzymes belong to the N-terminal nucleophile superfamily and are best known to catalyze the deconjugation of glycine or taurine from bile salts to release bile acid substrates for transformation and or metabolism in the gastrointestinal tract. Here, we identify and describe the BSH from a common member of the Plains bison microbiome, Arthrobacter citreus (BSH Ac ). Steady-state kinetic analyses demonstrated that BSH Ac is a broad-spectrum hydrolase with a preference for glycine-conjugates and deoxycholic acid (DCA). Second-order rate constants (k cat /K M ) for BSH Ac -catalyzed reactions of relevant bile salts-glyco- and tauro-conjugates of cholic acid and DCA- varied by ∼30-fold and measured between 1.4 × 10 5 and 4.3 × 10 6  M -1 s -1 . Interestingly, a pan-BSH inhibitor named AAA-10 acted as a slow irreversible inhibitor of BSH Ac with a rate of inactivation (k inact ) of ∼2 h -1 and a second order rate constant (k inact /K I ) of ∼24 M -1 s -1 for the process. Structural characterization of BSH Ac reacted with AAA-10 showed covalent modification of the N-terminal cysteine nucleophile, providing molecular details for an enzyme-stabilized product formed from this mechanism-based inhibitor's α-fluoromethyl ketone warhead. Structural comparison of the BSHs and BSH:inhibitor complexes highlighted the plasticity of the steroid-binding site, including a flexible loop that is variable across well-studied BSHs.
      Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article.
      (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)
    • Contributed Indexing:
      Keywords: bacteria; bile acid; enzyme inhibitor; enzyme kinetics; enzyme structure; hydrolase
    • Accession Number:
      EC 3.5.1.24 (choloylglycine hydrolase)
      EC 3.5.- (Amidohydrolases)
      0 (Bacterial Proteins)
      0 (Bile Acids and Salts)
    • Publication Date:
      Date Created: 20240914 Date Completed: 20241104 Latest Revision: 20241104
    • Publication Date:
      20241104
    • Accession Number:
      10.1016/j.jbc.2024.107769
    • Accession Number:
      39276930