Related Experiment Video
Updated: Jun 23, 2025
13:35
Structural Biology and Analytical Chemistry Approaches for Characterizing C-Glycoside Metabolic Enzymes in Human Gut Microbiota
Published on: May 23, 2025
293
Human gut microbes express functionally distinct endoglycosidases to metabolize the same N-glycan substrate
Diego E Sastre1, Nazneen Sultana2,3, Marcos V A S Navarro4,5
1Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA. dsastre@emory.edu.
Nature Communications
|June 15, 2024
Summary
Human gut bacteria like Bacteroides thetaiotaomicron possess multiple enzymes, such as endo-β-N-acetylglucosaminidases (ENGases), to efficiently break down high-mannose N-glycans. These distinct enzymes function optimally under different conditions, enabling versatile nutrient utilization in the gut.
Area of Science:
- Microbiology
- Glycobiology
- Structural Biology
Background:
- Bacteroidales are key human gut microbes with polysaccharide utilization loci (PULs) for glycan degradation.
- Bacteroides thetaiotaomicron utilizes high-mannose (HM) N-glycans via a surface endo-β-N-acetylglucosaminidase (ENGase), BT3987.
Purpose of the Study:
- To discover and characterize a novel ENGase (BT1285) from Bacteroides thetaiotaomicron involved in HM N-glycan catabolism.
- To elucidate the molecular mechanism of HM N-glycan hydrolysis by BT1285 and compare its properties with BT3987.
- To investigate the functional properties of HM-processing endoglycosidases from Alistipes finegoldii.
Main Methods:
- X-ray crystallography and electron microscopy for structural determination.
- Mass spectrometry-based activity assays and biophysical methods for functional characterization.
- Alanine scanning mutagenesis to probe enzyme mechanisms.
Main Results:
- A new GH18 family ENGase, BT1285, was identified in B. thetaiotaomicron, encoded in a distinct PUL.
- BT1285 exhibits higher affinity and faster hydrolysis of poorly accessible HM N-glycans compared to BT3987.
- Both BT1285 and BT3987 have optimal activity under different environmental conditions.
- Endoglycosidases from Alistipes finegoldii also show condition-specific functions.
Conclusions:
- Human gut microbes utilize distinct ENGases with condition-specific properties to optimize the metabolism of HM N-glycans.
- This enzymatic diversity represents an evolutionary strategy for efficient nutrient acquisition in the gastrointestinal tract.
More Related Videos
Related Concept Videos
01:24Oligosaccharide Assembly
2.8K
Protein glycosylation starts in the ER lumen and continues in the Golgi apparatus. Glycosyltransferases catalyze the addition of sugar molecules or glycosylation of proteins. Usually, these enzymes add sugars to the hydroxyl groups of selected serine or threonine residues to form O-linked glycans or the amino groups of asparagine residues to form N-linked glycans. Different positions on the same polypeptide chain can contain differently linked glycans.
Multiple sugar molecules that may or may...
Multiple sugar molecules that may or may...
2.8K
01:22Lysosomal Hydrolases
3.8K
Lysosomes are the site for the degradation of macromolecules and biological polymers released during membrane trafficking events such as secretory, endocytic, autophagic, and phagocytic pathways. The membrane-enclosed area of the lysosome, called the lumen, contains hydrolytic enzymes active in an acidic environment. These acid hydrolases are functional at a pH between 4.5 and 5 and are involved in cellular processes such as cell signaling, energy metabolism, restoration of the plasma membrane,...
3.8K
01:25Protein Glycosylation
6.9K
Glycosylation, the most common post-translational modification for proteins, serves diverse functions. Adding sugars to proteins makes the proteins more resistant to proteolytic digestion. Glycosylated proteins can act as markers and receptors to promote cell-cell adhesion. Additionally, they have many essential quality control functions in the cell, such as correct protein folding and facilitating transport of misfolded proteins to the cytosol, which can be degraded.
Glycosylation occurs in...
Glycosylation occurs in...
6.9K
01:50What is Monogastric Digestion?
71.1K
The human body contains a monogastric digestive system. In a monogastric digestive system, the stomach only contains one chamber in which it digests food. Several other animal species also have monogastric digestive systems, including pigs, horses, dogs, and birds. This chapter, however, focuses on the human digestive system.
71.1K
01:05Proteoglycans
3.9K
Glycans, a class of complex heterogeneous molecules, can be covalently attached to proteins to form glycosylated proteins that regulate various physiological and pathological processes. Glycosylated proteins or glycoproteins comprise N-linked and O-linked oligosaccharides. O-glycosylation is the most common type of protein glycosylation. Here, glycans attach to the oxygen atom of the hydroxyl groups of Serine or Threonine residues. O-linked glycosylation occurs later in protein processing,...
3.9K