Mouse Gut Microbiome-Encoded β-Glucuronidases Identified Using Metagenome Analysis Guided by Protein Structure

Area of Science:

• Microbiome Research
• Enzymology
• Bioinformatics

Background:

• Gut microbial beta-glucuronidase (GUS) enzymes are crucial for drug metabolism, carcinogenesis, and host-microbe interactions.
• Previous studies cataloged human gut GUS proteins, establishing a baseline for comparison.
• Mice are vital model organisms, making their gut microbial GUSome analysis critical for translational research.

Purpose of the Study:

• To create the first comprehensive catalog of mouse intestinal microbial GUS proteins (mouse gut GUSome).
• To compare the mouse gut GUSome with the human gut GUSome.
• To investigate the influence of host factors (strain, diet, housing) on mouse gut microbial GUS composition.

Main Methods:

• Metagenome analysis of 2.5 million unique proteins from diverse mouse gut microbiomes.
• Protein structure-guided analysis to identify and categorize GUS enzymes.
• Biochemical assays to assess the enzymatic activity of selected GUS proteins.

Main Results:

• Identified 444 unique mouse gut microbial GUS proteins, categorized into six functional groups.
• GUS enzymes were primarily encoded by Firmicutes (60%) and Bacteroidetes (21%).
• Mouse gut GUSome composition varied significantly with provider, location, strain, and diet, but not sex.
• Diet exhibited the most substantial impact on GUS gene composition.
• Biochemical analysis revealed variable efficacy in processing heparan oligosaccharides by low-fat-associated GUS enzymes.

Conclusions:

• A conserved core GUSome functionality exists between mouse and human gut bacteria, despite sequence-level differences.
• Mouse strain, provider, housing, and diet shape distinct gut microbial GUSomes.
• This study provides a foundational catalog of mouse gut microbial GUS enzymes, crucial for interpreting mouse model studies.