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Sastre DE, Sultana N, V A S Navarro M, Huliciak M, Du J, Cifuente JO, Flowers M, Liu X, Lollar P, Trastoy B, Guerin ME, Sundberg EJ. Human gut microbes express functionally distinct endoglycosidases to metabolize the same N-glycan substrate. Nat Commun 2024; 15:5123. [PMID: 38879612 PMCID: PMC11180146 DOI: 10.1038/s41467-024-48802-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Accepted: 05/15/2024] [Indexed: 06/18/2024] Open
Abstract
Bacteroidales (syn. Bacteroidetes) are prominent members of the human gastrointestinal ecosystem mainly due to their efficient glycan-degrading machinery, organized into gene clusters known as polysaccharide utilization loci (PULs). A single PUL was reported for catabolism of high-mannose (HM) N-glycan glyco-polypeptides in the gut symbiont Bacteroides thetaiotaomicron, encoding a surface endo-β-N-acetylglucosaminidase (ENGase), BT3987. Here, we discover an ENGase from the GH18 family in B. thetaiotaomicron, BT1285, encoded in a distinct PUL with its own repertoire of proteins for catabolism of the same HM N-glycan substrate as that of BT3987. We employ X-ray crystallography, electron microscopy, mass spectrometry-based activity measurements, alanine scanning mutagenesis and a broad range of biophysical methods to comprehensively define the molecular mechanism by which BT1285 recognizes and hydrolyzes HM N-glycans, revealing that the stabilities and activities of BT1285 and BT3987 were optimal in markedly different conditions. BT1285 exhibits significantly higher affinity and faster hydrolysis of poorly accessible HM N-glycans than does BT3987. We also find that two HM-processing endoglycosidases from the human gut-resident Alistipes finegoldii display condition-specific functional properties. Altogether, our data suggest that human gut microbes employ evolutionary strategies to express distinct ENGases in order to optimally metabolize the same N-glycan substrate in the gastroinstestinal tract.
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Affiliation(s)
- Diego E Sastre
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA.
| | - Nazneen Sultana
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
- Structural Biochemistry Unit, National Institute of Dental and Craniofacial Research (NIDCR/NIH), Bethesda, MD, USA
| | - Marcos V A S Navarro
- Institute of Physics (IFSC-USP), University of São Paulo, São Carlos, SP, Brazil
- Center for Innovative Proteomics, Cornell University, Ithaca, NY, USA
| | - Maros Huliciak
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Jonathan Du
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
- Sydney Pharmacy School, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW, Australia
| | - Javier O Cifuente
- Instituto Biofisika (UPV/EHU, CSIC), University of the Basque Country, Leioa, Spain
| | - Maria Flowers
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Xu Liu
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Pete Lollar
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
| | - Beatriz Trastoy
- Structural Glycoimmunology Laboratory, Biobizkaia Health Research Institute, Barakaldo, Bizkaia, Spain
- Ikerbasque, Basque Foundation for Science, Bilbao, Spain
| | - Marcelo E Guerin
- Structural Glycobiology Laboratory, Department of Structural and Molecular Biology, Molecular Biology Institute of Barcelona (IBMB), Spanish National Research Council (CSIC), Barcelona Science Park, c/Baldiri Reixac 4-8, Tower R, Barcelona, Catalonia, Spain
| | - Eric J Sundberg
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA.
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Li S, Chen M, Wang Z, Abudourexiti W, Zhang L, Ding C, Ding L, Gong J. Ant may well destroy a whole dam: glycans of colonic mucus barrier disintegrated by gut bacteria. Microbiol Res 2024; 281:127599. [PMID: 38219635 DOI: 10.1016/j.micres.2023.127599] [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] [Received: 09/25/2023] [Revised: 12/29/2023] [Accepted: 12/30/2023] [Indexed: 01/16/2024]
Abstract
The colonic mucus layer plays a critical role in maintaining the integrity of the colonic mucosal barrier, serving as the primary defense against colonic microorganisms. Predominantly composed of mucin 2 (MUC2), a glycosylation-rich protein, the mucus layer forms a gel-like coating that covers the colonic epithelium surface. This layer provides a habitat for intestinal microorganisms, which can utilize mucin glycans present in the mucus layer as a sustainable source of nutrients. Additionally, metabolites produced by the microbiota during the metabolism of mucus glycans have a profound impact on host health. Under normal conditions, the production and consumption of mucus maintain a dynamic balance. However, several studies have demonstrated that certain factors, such as dietary fiber deficiency, can enhance the metabolism of mucus glycans by gut bacteria, thereby disturbing this balance and weakening the mucus barrier function of the mucus layer. To better understand the occurrence and development of colon-related diseases, it is crucial to investigate the complex metabolic patterns of mucus glycosylation by intestinal microorganisms. Our objective was to comprehensively review these patterns in order to clarify the effects of mucus layer glycan metabolism by intestinal microorganisms on the host.
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Affiliation(s)
- Song Li
- Department of General Surgery, Affiliated Jinling Hospital, Medical School, Nanjing University, Nanjing, China
| | - Mingfei Chen
- Department of General Surgery, Affiliated Jinling Hospital, Medical School, Nanjing University, Nanjing, China
| | - Zhongyuan Wang
- Department of General Surgery, Affiliated Jinling Hospital, Medical School, Nanjing University, Nanjing, China
| | - Waresi Abudourexiti
- Department of General Surgery, Affiliated Jinling Hospital, Medical School, Nanjing University, Nanjing, China
| | - Liang Zhang
- Department of Gastrointestinal Surgery, Xuzhou Central Hospital, Xuzhou Clinical School of Xuzhou Medical College, Jiangsu, China
| | - Chao Ding
- Department of General Surgery, Affiliated Drum Tower Hospital, Medical School, Nanjing University, Nanjing, China.
| | - Lin Ding
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China; Chemistry and Biomedicine Innovation Center (ChemBIC), Nanjing University, Nanjing 210023, China.
| | - Jianfeng Gong
- Department of General Surgery, Affiliated Jinling Hospital, Medical School, Nanjing University, Nanjing, China.
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Bains RK, Nasseri SA, Liu F, Wardman JF, Rahfeld P, Withers SG. Characterization of a new family of 6-sulfo-N-acetylglucosaminidases. J Biol Chem 2023; 299:105214. [PMID: 37660924 PMCID: PMC10570127 DOI: 10.1016/j.jbc.2023.105214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 08/12/2023] [Accepted: 08/18/2023] [Indexed: 09/05/2023] Open
Abstract
Sulfation is widespread in nature and plays an important role in modulating biological function. Among the strategies developed by microbes to access sulfated oligosaccharides as a nutrient source is the production of 6-sulfoGlcNAcases to selectively release 6-sulfoGlcNAc from target oligosaccharides. Thus far, all 6-sulfoGlcNAcases identified have belonged to the large GH20 family of β-hexosaminidases. Ηere, we identify and characterize a new, highly specific non-GH20 6-sulfoGlcNAcase from Streptococcus pneumoniae TIGR4, Sp_0475 with a greater than 110,000-fold preference toward N-acetyl-β-D-glucosamine-6-sulfate substrates over the nonsulfated version. Sp_0475 shares distant sequence homology with enzymes of GH20 and with the newly formed GH163 family. However, the sequence similarity between them is sufficiently low that Sp_0475 has been assigned as the founding member of a new glycoside hydrolase family, GH185. By combining results from site-directed mutagenesis with mechanistic studies and bioinformatics we provide insight into the substrate specificity, mechanism, and key active site residues of Sp_0475. Enzymes of the GH185 family follow a substrate-assisted mechanism, consistent with their distant homology to the GH20 family, but the catalytic residues involved are quite different. Taken together, our results highlight in more detail how microbes can degrade sulfated oligosaccharides for nutrients.
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Affiliation(s)
- Rajneesh K Bains
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada; Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
| | - Seyed A Nasseri
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada; Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
| | - Feng Liu
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada; Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jacob F Wardman
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada; Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada; Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Peter Rahfeld
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada; Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
| | - Stephen G Withers
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada; Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada; Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada.
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