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Guzior DV, Okros M, Shivel M, Armwald B, Bridges C, Fu Y, Martin C, Schilmiller AL, Miller WM, Ziegler KM, Sims MD, Maddens ME, Graham SF, Hausinger RP, Quinn RA. Bile salt hydrolase acyltransferase activity expands bile acid diversity. Nature 2024; 626:852-858. [PMID: 38326608 DOI: 10.1038/s41586-024-07017-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 01/02/2024] [Indexed: 02/09/2024]
Abstract
Bile acids (BAs) are steroid detergents in bile that contribute to the absorption of fats and fat-soluble vitamins while shaping the gut microbiome because of their antimicrobial properties1-4. Here we identify the enzyme responsible for a mechanism of BA metabolism by the gut microbiota involving amino acid conjugation to the acyl-site of BAs, thus producing a diverse suite of microbially conjugated bile acids (MCBAs). We show that this transformation is mediated by acyltransferase activity of bile salt hydrolase (bile salt hydrolase/transferase, BSH/T). Clostridium perfringens BSH/T rapidly performed acyl transfer when provided various amino acids and taurocholate, glycocholate or cholate, with an optimum at pH 5.3. Amino acid conjugation by C. perfringens BSH/T was diverse, including all proteinaceous amino acids except proline and aspartate. MCBA production was widespread among gut bacteria, with strain-specific amino acid use. Species with similar BSH/T amino acid sequences had similar conjugation profiles and several bsh/t alleles correlated with increased conjugation diversity. Tertiary structure mapping of BSH/T followed by mutagenesis experiments showed that active site structure affects amino acid selectivity. These MCBA products had antimicrobial properties, where greater amino acid hydrophobicity showed greater antimicrobial activity. Inhibitory concentrations of MCBAs reached those measured natively in the mammalian gut. MCBAs fed to mice entered enterohepatic circulation, in which liver and gallbladder concentrations varied depending on the conjugated amino acid. Quantifying MCBAs in human faecal samples showed that they reach concentrations equal to or greater than secondary and primary BAs and were reduced after bariatric surgery, thus supporting MCBAs as a significant component of the BA pool that can be altered by changes in gastrointestinal physiology. In conclusion, the inherent acyltransferase activity of BSH/T greatly diversifies BA chemistry, creating a set of previously underappreciated metabolites with the potential to affect the microbiome and human health.
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Affiliation(s)
- Douglas V Guzior
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
- Department of Microbiology, Genetics & Immunology, Michigan State University, East Lansing, MI, USA
| | - Maxwell Okros
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - Madison Shivel
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
- College of Osteopathic Medicine, Michigan State University, East Lansing, MI, USA
| | - Bruin Armwald
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
- College of Osteopathic Medicine, Michigan State University, East Lansing, MI, USA
| | - Christopher Bridges
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
- Department of Microbiology, Genetics & Immunology, Michigan State University, East Lansing, MI, USA
| | - Yousi Fu
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - Christian Martin
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - Anthony L Schilmiller
- Mass Spectrometry and Metabolomics Core, Michigan State University, East Lansing, MI, USA
| | - Wendy M Miller
- Corewell Health, William Beaumont University Hospital, Royal Oak, MI, USA
- Oakland University, William Beaumont School of Medicine, Rochester, MI, USA
| | - Kathryn M Ziegler
- Corewell Health, William Beaumont University Hospital, Royal Oak, MI, USA
- Oakland University, William Beaumont School of Medicine, Rochester, MI, USA
| | - Matthew D Sims
- Corewell Health, William Beaumont University Hospital, Royal Oak, MI, USA
- Oakland University, William Beaumont School of Medicine, Rochester, MI, USA
| | - Michael E Maddens
- Corewell Health, William Beaumont University Hospital, Royal Oak, MI, USA
- Oakland University, William Beaumont School of Medicine, Rochester, MI, USA
| | - Stewart F Graham
- Corewell Health, William Beaumont University Hospital, Royal Oak, MI, USA
- Oakland University, William Beaumont School of Medicine, Rochester, MI, USA
- Beaumont Research Institute, Royal Oak, MI, USA
| | - Robert P Hausinger
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
- Department of Microbiology, Genetics & Immunology, Michigan State University, East Lansing, MI, USA
| | - Robert A Quinn
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA.
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Joyce SA, Clarke DJ. Microbial metabolites as modulators of host physiology. Adv Microb Physiol 2024; 84:83-133. [PMID: 38821635 DOI: 10.1016/bs.ampbs.2023.12.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2024]
Abstract
The gut microbiota is increasingly recognised as a key player in influencing human health and changes in the gut microbiota have been strongly linked with many non-communicable conditions in humans such as type 2 diabetes, obesity and cardiovascular disease. However, characterising the molecular mechanisms that underpin these associations remains an important challenge for researchers. The gut microbiota is a complex microbial community that acts as a metabolic interface to transform ingested food (and other xenobiotics) into metabolites that are detected in the host faeces, urine and blood. Many of these metabolites are only produced by microbes and there is accumulating evidence to suggest that these microbe-specific metabolites do act as effectors to influence human physiology. For example, the gut microbiota can digest dietary complex polysaccharides (such as fibre) into short-chain fatty acids (SCFA) such as acetate, propionate and butyrate that have a pervasive role in host physiology from nutrition to immune function. In this review we will outline our current understanding of the role of some key microbial metabolites, such as SCFA, indole and bile acids, in human health. Whilst many studies linking microbial metabolites with human health are correlative we will try to highlight examples where genetic evidence is available to support a specific role for a microbial metabolite in host health and well-being.
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Affiliation(s)
- Susan A Joyce
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland; APC Microbiome Ireland, University College Cork, Cork, Ireland
| | - David J Clarke
- APC Microbiome Ireland, University College Cork, Cork, Ireland; School of Microbiology, University College Cork, Cork, Ireland.
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Song Z, Feng S, Zhou X, Song Z, Li J, Li P. Taxonomic identification of bile salt hydrolase-encoding lactobacilli: Modulation of the enterohepatic bile acid profile. IMETA 2023; 2:e128. [PMID: 38867937 PMCID: PMC10989828 DOI: 10.1002/imt2.128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 06/19/2023] [Accepted: 06/23/2023] [Indexed: 06/14/2024]
Abstract
Bile salt hydrolases (BSHs) are enzymes that are essential for the enterohepatic metabolism of bile acids (BAs). BSHs catalyze the production of unconjugated BAs and regulate the homeostasis of BA pool. This study identified Lactobacillus as a crucial BSH-encoding genus, and 16 main species were obtained using metagenomic data from publicly available human gut microbiome databases. Then, the 16 species of lactobacilli were classified into four typical categories by BSH phylotypes, including five species encoding BSH-T0, six species encoding BSH-T2, four species encoding BSH-T3, and Ligilactobacillus salivarius encoding both BSH-T0 and BSH-T3. The lactobacilli with the highest in vitro deconjugation activities against seven conjugated BAs were the BSH-T3-encoding strains. Furthermore, in vivo studies in mice administered four representative lactobacilli strains encoding different BSH phylotypes showed that treatment with BSH-T3-encoding Limosilactobacillus reuteri altered the structure of the gut microbiome and metabolome and significantly increased the levels of unconjugated BAs and total BA excretion. Our findings facilitated the taxonomic identification of crucial BSH-encoding lactobacilli in human gut microbiota and shed light on their contributions toward modulation of the enterohepatic circulation of BAs, which will contribute to future therapeutic applications of BSH-encoding probiotics to improve human health.
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Affiliation(s)
- Ziwei Song
- State Key Laboratory of Natural MedicinesChina Pharmaceutical UniversityNanjingChina
| | - Shuo Feng
- School of Life Science and TechnologyChina Pharmaceutical UniversityNanjingChina
| | - Xingchen Zhou
- Beijing Key Laboratory of New Molecular Diagnosis Technologies for Infectious Disease, Department of BiotechnologyBeijing Institute of Radiation MedicineBeijingChina
| | - Zhengxing Song
- School of Life Science and TechnologyChina Pharmaceutical UniversityNanjingChina
| | - Jing Li
- State Key Laboratory of Natural MedicinesChina Pharmaceutical UniversityNanjingChina
- School of Life Science and TechnologyChina Pharmaceutical UniversityNanjingChina
| | - Ping Li
- State Key Laboratory of Natural MedicinesChina Pharmaceutical UniversityNanjingChina
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