1
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Basu A, Adams AND, Degnan PH, Vanderpool CK. Determinants of raffinose family oligosaccharide use in Bacteroides species. J Bacteriol 2024:e0023524. [PMID: 39330254 DOI: 10.1128/jb.00235-24] [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: 06/03/2024] [Accepted: 09/06/2024] [Indexed: 09/28/2024] Open
Abstract
Bacteroides species are successful colonizers of the human colon and can utilize a wide variety of complex polysaccharides and oligosaccharides that are indigestible by the host. To do this, they use enzymes encoded in polysaccharide utilization loci (PULs). While recent work has uncovered the PULs required for the use of some polysaccharides, how Bacteroides utilize smaller oligosaccharides is less well studied. Raffinose family oligosaccharides (RFOs) are abundant in plants, especially legumes, and consist of variable units of galactose linked by α-1,6 bonds to a sucrose (glucose α-1-β-2 fructose) moiety. Previous work showed that an α-galactosidase, BT1871, is required for RFO utilization in Bacteroides thetaiotaomicron. Here, we identify two different types of mutations that increase BT1871 mRNA levels and improve B. thetaiotaomicron growth on RFOs. First, a novel spontaneous duplication of BT1872 and BT1871 places these genes under the control of a ribosomal promoter, driving high BT1871 transcription. Second, nonsense mutations in a gene encoding the PUL24 anti-sigma factor likewise increase BT1871 transcription. We then show that hydrolases from PUL22 work together with BT1871 to break down the sucrose moiety of RFOs and determine that the master regulator of carbohydrate utilization (BT4338) plays a role in RFO utilization in B. thetaiotaomicron. Examining the genomes of other Bacteroides species, we found homologs of BT1871 in a subset and showed that representative strains of species with a BT1871 homolog grew better on melibiose than species that lack a BT1871 homolog. Altogether, our findings shed light on how an important gut commensal utilizes an abundant dietary oligosaccharide. IMPORTANCE The gut microbiome is important in health and disease. The diverse and densely populated environment of the gut makes competition for resources fierce. Hence, it is important to study the strategies employed by microbes for resource usage. Raffinose family oligosaccharides are abundant in plants and are a major source of nutrition for the microbiota in the colon since they remain undigested by the host. Here, we study how the model commensal organism, Bacteroides thetaiotaomicron utilizes raffinose family oligosaccharides. This work highlights how an important member of the microbiota uses an abundant dietary resource.
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Affiliation(s)
- Anubhav Basu
- Department of Microbiology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
| | - Amanda N D Adams
- Department of Microbiology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Patrick H Degnan
- Department of Microbiology and Plant Pathology, University of California Riverside, Riverside, California, USA
| | - Carin K Vanderpool
- Department of Microbiology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
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2
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Huang Y, Cao J, Zhu M, Wang Z, Jin Z, Xiong Z. Nontoxigenic Bacteroides fragilis: A double-edged sword. Microbiol Res 2024; 286:127796. [PMID: 38870618 DOI: 10.1016/j.micres.2024.127796] [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: 09/23/2023] [Revised: 04/12/2024] [Accepted: 05/31/2024] [Indexed: 06/15/2024]
Abstract
The contribution of commensal microbes to human health and disease is unknown. Bacteroides fragilis (B. fragilis) is an opportunistic pathogen and a common colonizer of the human gut. Nontoxigenic B. fragilis (NTBF) and enterotoxigenic B. fragilis (ETBF) are two kinds of B. fragilis. NTBF has been shown to affect the host immune system and interact with gut microbes and pathogenic microbes. Previous studies indicated that certain strains of B. fragilis have the potential to serve as probiotics, based on their observed relationship with the immune system. However, several recent studies have shown detrimental effects on the host when beneficial gut bacteria are found in the digestive system or elsewhere. In some pathological conditions, NTBF may have adverse reactions. This paper presents a comprehensive analysis of NTBF ecology from the host-microbe perspective, encompassing molecular disease mechanisms analysis, bacteria-bacteria interaction, bacteria-host interaction, and the intricate ecological context of the gut. Our review provides much-needed insights into the precise application of NTBF.
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Affiliation(s)
- Yumei Huang
- Department of Gastroenterology, Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Jiali Cao
- Department of Gastroenterology, Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Mengpei Zhu
- Department of Gastroenterology, Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Ziwen Wang
- Department of Gastroenterology, Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Ze Jin
- Department of Gastroenterology, Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Zhifan Xiong
- Department of Gastroenterology, Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
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3
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Torres M, Paszti S, Eberl L. Shedding light on bacteria-host interactions with the aid of TnSeq approaches. mBio 2024; 15:e0039024. [PMID: 38722161 PMCID: PMC11237515 DOI: 10.1128/mbio.00390-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2024] Open
Abstract
Bacteria are highly adaptable and grow in diverse niches, where they often interact with eukaryotic organisms. These interactions with different hosts span the entire spectrum from symbiosis to pathogenicity and thus determine the lifestyle of the bacterium. Knowledge of the genetic determinants involved in animal and plant host colonization by pathogenic and mutualistic bacteria is not only crucial to discover new drug targets for disease management but also for developing novel biostimulant strategies. In the last decades, significant progress in genome-wide high-throughput technologies such as transposon insertion sequencing has led to the identification of pathways that enable efficient host colonization. However, the extent to which similar genes play a role in this process in different bacteria is yet unclear. This review highlights the commonalities and specificities of bacterial determinants important for bacteria-host interaction.
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Affiliation(s)
- Marta Torres
- Department of Plant and Microbial Biology, University of Zurich, Zürich, Switzerland
| | - Sarah Paszti
- Department of Plant and Microbial Biology, University of Zurich, Zürich, Switzerland
| | - Leo Eberl
- Department of Plant and Microbial Biology, University of Zurich, Zürich, Switzerland
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4
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Basu A, Adams AN, Degnan PH, Vanderpool CK. Determinants of raffinose family oligosaccharide use in Bacteroides species. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.07.597959. [PMID: 38895307 PMCID: PMC11185731 DOI: 10.1101/2024.06.07.597959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Bacteroides species are successful colonizers of the human gut and can utilize a wide variety of complex polysaccharides and oligosaccharides that are indigestible by the host. To do this, they use enzymes encoded in Polysaccharide Utilization Loci (PULs). While recent work has uncovered the PULs required for use of some polysaccharides, how Bacteroides utilize smaller oligosaccharides is less well studied. Raffinose family oligosaccharides (RFOs) are abundant in plants, especially legumes, and consist of variable units of galactose linked by α-1,6 bonds to a sucrose (glucose α-1-β-2 fructose) moiety. Previous work showed that an α-galactosidase, BT1871, is required for RFO utilization in Bacteroides thetaiotaomicron. Here, we identify two different types of mutations that increase BT1871 mRNA levels and improve B. thetaiotaomicron growth on RFOs. First, a novel spontaneous duplication of BT1872 and BT1871 places these genes under control of a ribosomal promoter, driving high BT1871 transcription. Second, nonsense mutations in a gene encoding the PUL24 anti-sigma factor likewise increase BT1871 transcription. We then show that hydrolases from PUL22 work together with BT1871 to break down the sucrose moiety of RFOs and determine that the master regulator of carbohydrate utilization (BT4338) plays a role in RFO utilization in B. thetaiotaomicron. Examining the genomes of other Bacteroides species, we found homologs of BT1871 in subset and show that representative strains of species containing a BT1871 homolog grew better on melibiose than species that lack a BT1871 homolog. Altogether, our findings shed light on how an important gut commensal utilizes an abundant dietary oligosaccharide.
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Affiliation(s)
- Anubhav Basu
- Department of Microbiology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
| | - Amanda N.D. Adams
- Department of Microbiology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Patrick H. Degnan
- Department of Microbiology and Plant Pathology, University of California Riverside, Riverside, California, USA
| | - Carin K. Vanderpool
- Department of Microbiology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
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5
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Groisman EA, Han W, Krypotou E. Advancing the fitness of gut commensal bacteria. Science 2023; 382:766-768. [PMID: 37972163 PMCID: PMC10838159 DOI: 10.1126/science.adh9165] [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] [Indexed: 11/19/2023]
Abstract
Nutrient starvation of beneficial bacteria helps them colonize the human gut.
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Affiliation(s)
- Eduardo A. Groisman
- Department of Microbial Pathogenesis, Yale School of Medicine; New Haven, CT, USA
| | - Weiwei Han
- Department of Microbial Pathogenesis, Yale School of Medicine; New Haven, CT, USA
| | - Emilia Krypotou
- Department of Microbial Pathogenesis, Yale School of Medicine; New Haven, CT, USA
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6
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Liu B, Garza DR, Gonze D, Krzynowek A, Simoens K, Bernaerts K, Geirnaert A, Faust K. Starvation responses impact interaction dynamics of human gut bacteria Bacteroides thetaiotaomicron and Roseburia intestinalis. THE ISME JOURNAL 2023; 17:1940-1952. [PMID: 37670028 PMCID: PMC10579405 DOI: 10.1038/s41396-023-01501-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 08/21/2023] [Accepted: 08/23/2023] [Indexed: 09/07/2023]
Abstract
Bacterial growth often alters the environment, which in turn can impact interspecies interactions among bacteria. Here, we used an in vitro batch system containing mucin beads to emulate the dynamic host environment and to study its impact on the interactions between two abundant and prevalent human gut bacteria, the primary fermenter Bacteroides thetaiotaomicron and the butyrate producer Roseburia intestinalis. By combining machine learning and flow cytometry, we found that the number of viable B. thetaiotaomicron cells decreases with glucose consumption due to acid production, while R. intestinalis survives post-glucose depletion by entering a slow growth mode. Both species attach to mucin beads, but only viable cell counts of B. thetaiotaomicron increase significantly. The number of viable co-culture cells varies significantly over time compared to those of monocultures. A combination of targeted metabolomics and RNA-seq showed that the slow growth mode of R. intestinalis represents a diauxic shift towards acetate and lactate consumption, whereas B. thetaiotaomicron survives glucose depletion and low pH by foraging on mucin sugars. In addition, most of the mucin monosaccharides we tested inhibited the growth of R. intestinalis but not B. thetaiotaomicron. We encoded these causal relationships in a kinetic model, which reproduced the observed dynamics. In summary, we explored how R. intestinalis and B. thetaiotaomicron respond to nutrient scarcity and how this affects their dynamics. We highlight the importance of understanding bacterial metabolic strategies to effectively modulate microbial dynamics in changing conditions.
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Affiliation(s)
- Bin Liu
- Department of Microbiology, Immunology and Transplantation, Rega Institute for Medical Research, Laboratory of Molecular Bacteriology, KU Leuven, B-3000, Leuven, Belgium
| | - Daniel Rios Garza
- Department of Microbiology, Immunology and Transplantation, Rega Institute for Medical Research, Laboratory of Molecular Bacteriology, KU Leuven, B-3000, Leuven, Belgium
| | - Didier Gonze
- Unité de Chronobiologie Théorique, Faculté des Sciences, CP 231, Université Libre de Bruxelles, Bvd du Triomphe, B-1050, Bruxelles, Belgium
| | - Anna Krzynowek
- Department of Microbiology, Immunology and Transplantation, Rega Institute for Medical Research, Laboratory of Molecular Bacteriology, KU Leuven, B-3000, Leuven, Belgium
| | - Kenneth Simoens
- Department of Chemical Engineering, Chemical and Biochemical Reactor Engineering and Safety (CREaS), KU Leuven, B-3001, Leuven, Belgium
| | - Kristel Bernaerts
- Department of Chemical Engineering, Chemical and Biochemical Reactor Engineering and Safety (CREaS), KU Leuven, B-3001, Leuven, Belgium
| | - Annelies Geirnaert
- Laboratory of Food Biotechnology, Department of Health Sciences and Technology, Institute of Food, Nutrition and Health, ETH Zürich, CH-8092, Zürich, Switzerland
| | - Karoline Faust
- Department of Microbiology, Immunology and Transplantation, Rega Institute for Medical Research, Laboratory of Molecular Bacteriology, KU Leuven, B-3000, Leuven, Belgium.
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7
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Koh YC, Kuo LH, Tung YC, Weerawatanakorn M, Pan MH. Identification of Indicative Gut Microbial Guilds in a Natural Aging Mouse Model. ACS OMEGA 2023; 8:36569-36580. [PMID: 37810685 PMCID: PMC10552476 DOI: 10.1021/acsomega.3c05949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Accepted: 09/12/2023] [Indexed: 10/10/2023]
Abstract
Gut microbial dysbiosis during later life may contribute to health conditions, possibly due to an increase in intestinal permeability, immune changes, and systemic inflammation. Mouse models have been employed to determine the influence of gut microbes on aging; however, suitable gut microbial indicators are currently lacking. Therefore, this study aimed to determine the gut microbial indicators and their potential guilds in a natural aging mouse model. In agreement with previous studies, alpha diversity indices-including observed OTUs, ACE, Chao1, and Simpson-were significantly lower in aged mice than in younger mice. The results of beta diversity analysis revealed the compositional differences between young and aged mice, and the MRPP, ANOSIM, and Adonis tests indicated that the results were representative. By employing ANCOM and LEfSe analyses, Bacteroides thetaiotaomicron (Bacteroides) and Anaeroplasma were identified as the indicators of young and aged mice, respectively. Notably, these indicators were still present after 3 months. The result of network analysis confirmed the negative correlation of these genera in mice, and the potential guild members were identified based on the increased abundance of Anaeroplasma in aged mice. The gut microbes of aged mice tend to correspond to those involved in human diseases, selenocompound metabolism, and glycolysis/gluconeogenesis in functional predictions. In this study, the gut microbial indicators in aged mice have been identified, and it is envisaged that these findings could provide a new approach for future studies of antiaging.
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Affiliation(s)
- Yen-Chun Koh
- Institute
of Food Science and Technology, National
Taiwan University, Taipei 10617, Taiwan
| | - Lee-Han Kuo
- Institute
of Food Science and Technology, National
Taiwan University, Taipei 10617, Taiwan
| | - Yen-Chen Tung
- Department
of Food Science, National Ilan University, Yilan 26041, Taiwan
| | - Monthana Weerawatanakorn
- Department
of Agro-Industry, Faculty of Agriculture, Natural Resources and Environment, Naresuan University, Phitsanulok 65000, Thailand
| | - Min-Hsiung Pan
- Institute
of Food Science and Technology, National
Taiwan University, Taipei 10617, Taiwan
- Department
of Medical Research, China Medical University Hospital, China Medical University, Taichung 40402, Taiwan
- Department
of Health and Nutrition Biotechnology, Asia
University, Taichung 41354, Taiwan
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8
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McCann JR, Rawls JF. Essential Amino Acid Metabolites as Chemical Mediators of Host-Microbe Interaction in the Gut. Annu Rev Microbiol 2023; 77:479-497. [PMID: 37339735 PMCID: PMC11188676 DOI: 10.1146/annurev-micro-032421-111819] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/22/2023]
Abstract
Amino acids are indispensable substrates for protein synthesis in all organisms and incorporated into diverse aspects of metabolic physiology and signaling. However, animals lack the ability to synthesize several of them and must acquire these essential amino acids from their diet or perhaps their associated microbial communities. The essential amino acids therefore occupy a unique position in the health of animals and their relationships with microbes. Here we review recent work connecting microbial production and metabolism of essential amino acids to host biology, and the reciprocal impacts of host metabolism of essential amino acids on their associated microbes. We focus on the roles of the branched-chain amino acids (valine, leucine, and isoleucine) and tryptophan on host-microbe communication in the intestine of humans and other vertebrates. We then conclude by highlighting research questions surrounding the less-understood aspects of microbial essential amino acid synthesis in animal hosts.
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Affiliation(s)
- Jessica R McCann
- Department of Molecular Genetics and Microbiology, Duke Microbiome Center, Duke University School of Medicine, Durham, North Carolina, USA; ,
| | - John F Rawls
- Department of Molecular Genetics and Microbiology, Duke Microbiome Center, Duke University School of Medicine, Durham, North Carolina, USA; ,
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9
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Abstract
Oxidative stress is an important and pervasive physical stress encountered by all kingdoms of life, including bacteria. In this review, we briefly describe the nature of oxidative stress, highlight well-characterized protein-based sensors (transcription factors) of reactive oxygen species that serve as standards for molecular sensors in oxidative stress, and describe molecular studies that have explored the potential of direct RNA sensitivity to oxidative stress. Finally, we describe the gaps in knowledge of RNA sensors-particularly regarding the chemical modification of RNA nucleobases. RNA sensors are poised to emerge as an essential layer of understanding and regulating dynamic biological pathways in oxidative stress responses in bacteria and, thus, also represent an important frontier of synthetic biology.
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Affiliation(s)
- Ryan Buchser
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas, USA;
| | - Phillip Sweet
- Integrative Life Sciences Program, University of Texas at Austin, Austin, Texas, USA
| | - Aparna Anantharaman
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas, USA;
| | - Lydia Contreras
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas, USA;
- Integrative Life Sciences Program, University of Texas at Austin, Austin, Texas, USA
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10
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Krypotou E, Townsend GE, Gao X, Tachiyama S, Liu J, Pokorzynski ND, Goodman AL, Groisman EA. Bacteria require phase separation for fitness in the mammalian gut. Science 2023; 379:1149-1156. [PMID: 36927025 PMCID: PMC10148683 DOI: 10.1126/science.abn7229] [Citation(s) in RCA: 23] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 02/10/2023] [Indexed: 03/18/2023]
Abstract
Therapeutic manipulation of the gut microbiota holds great potential for human health. The mechanisms bacteria use to colonize the gut therefore present valuable targets for clinical intervention. We now report that bacteria use phase separation to enhance fitness in the mammalian gut. We establish that the intrinsically disordered region (IDR) of the broadly and highly conserved transcription termination factor Rho is necessary and sufficient for phase separation in vivo and in vitro in the human commensal Bacteroides thetaiotaomicron. Phase separation increases transcription termination by Rho in an IDR-dependent manner. Moreover, the IDR is critical for gene regulation in the gut. Our findings expose phase separation as vital for host-commensal bacteria interactions and relevant for novel clinical applications.
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Affiliation(s)
- Emilia Krypotou
- Department of Microbial Pathogenesis, Yale School of Medicine; 295 Congress Avenue, New Haven, CT 06536, USA
- Yale Microbial Sciences Institute; P.O. Box 27389, West Haven, CT, 06516, USA
| | - Guy E. Townsend
- Department of Microbial Pathogenesis, Yale School of Medicine; 295 Congress Avenue, New Haven, CT 06536, USA
- Yale Microbial Sciences Institute; P.O. Box 27389, West Haven, CT, 06516, USA
- Department of Biochemistry and Molecular Biology, Penn State College of Medicine, 700 HMC Crescent Road, Hershey, PA 17033
| | - Xiaohui Gao
- Department of Microbial Pathogenesis, Yale School of Medicine; 295 Congress Avenue, New Haven, CT 06536, USA
| | - Shoichi Tachiyama
- Department of Microbial Pathogenesis, Yale School of Medicine; 295 Congress Avenue, New Haven, CT 06536, USA
- Yale Microbial Sciences Institute; P.O. Box 27389, West Haven, CT, 06516, USA
| | - Jun Liu
- Department of Microbial Pathogenesis, Yale School of Medicine; 295 Congress Avenue, New Haven, CT 06536, USA
- Yale Microbial Sciences Institute; P.O. Box 27389, West Haven, CT, 06516, USA
| | - Nick D. Pokorzynski
- Department of Microbial Pathogenesis, Yale School of Medicine; 295 Congress Avenue, New Haven, CT 06536, USA
| | - Andrew L. Goodman
- Department of Microbial Pathogenesis, Yale School of Medicine; 295 Congress Avenue, New Haven, CT 06536, USA
- Yale Microbial Sciences Institute; P.O. Box 27389, West Haven, CT, 06516, USA
| | - Eduardo A. Groisman
- Department of Microbial Pathogenesis, Yale School of Medicine; 295 Congress Avenue, New Haven, CT 06536, USA
- Yale Microbial Sciences Institute; P.O. Box 27389, West Haven, CT, 06516, USA
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11
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Han W, Peng B, Wang C, Townsend GE, Barry NA, Peske F, Goodman AL, Liu J, Rodnina MV, Groisman EA. Gut colonization by Bacteroides requires translation by an EF-G paralog lacking GTPase activity. EMBO J 2023; 42:e112372. [PMID: 36472247 PMCID: PMC9841332 DOI: 10.15252/embj.2022112372] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 11/11/2022] [Accepted: 11/11/2022] [Indexed: 12/12/2022] Open
Abstract
Protein synthesis is crucial for cell growth and survival yet one of the most energy-consuming cellular processes. How, then, do cells sustain protein synthesis under starvation conditions when energy is limited? To accelerate the translocation of mRNA-tRNAs through the ribosome, bacterial elongation factor G (EF-G) hydrolyzes energy-rich guanosine triphosphate (GTP) for every amino acid incorporated into a protein. Here, we identify an EF-G paralog-EF-G2-that supports translocation without hydrolyzing GTP in the gut commensal bacterium Bacteroides thetaiotaomicron. EF-G2's singular ability to sustain protein synthesis, albeit at slow rates, is crucial for bacterial gut colonization. EF-G2 is ~10-fold more abundant than canonical EF-G1 in bacteria harvested from murine ceca and, unlike EF-G1, specifically accumulates during carbon starvation. Moreover, we uncover a 26-residue region unique to EF-G2 that is essential for protein synthesis, EF-G2 dissociation from the ribosome, and responsible for the absence of GTPase activity. Our findings reveal how cells curb energy consumption while maintaining protein synthesis to advance fitness in nutrient-fluctuating environments.
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Affiliation(s)
- Weiwei Han
- Department of Microbial PathogenesisYale School of MedicineNew HavenCTUSA
- Yale Microbial Sciences InstituteWest HavenCTUSA
| | - Bee‐Zen Peng
- Department of Physical BiochemistryMax Planck Institute for Multidisciplinary SciencesGöttingenGermany
| | - Chunyan Wang
- Department of Microbial PathogenesisYale School of MedicineNew HavenCTUSA
- Yale Microbial Sciences InstituteWest HavenCTUSA
| | - Guy E Townsend
- Department of Microbial PathogenesisYale School of MedicineNew HavenCTUSA
- Yale Microbial Sciences InstituteWest HavenCTUSA
- Present address:
Department of Biochemistry and Molecular BiologyPenn State College of MedicineHersheyPAUSA
| | - Natasha A Barry
- Department of Microbial PathogenesisYale School of MedicineNew HavenCTUSA
- Yale Microbial Sciences InstituteWest HavenCTUSA
| | - Frank Peske
- Department of Physical BiochemistryMax Planck Institute for Multidisciplinary SciencesGöttingenGermany
| | - Andrew L Goodman
- Department of Microbial PathogenesisYale School of MedicineNew HavenCTUSA
- Yale Microbial Sciences InstituteWest HavenCTUSA
| | - Jun Liu
- Department of Microbial PathogenesisYale School of MedicineNew HavenCTUSA
- Yale Microbial Sciences InstituteWest HavenCTUSA
| | - Marina V Rodnina
- Department of Physical BiochemistryMax Planck Institute for Multidisciplinary SciencesGöttingenGermany
| | - Eduardo A Groisman
- Department of Microbial PathogenesisYale School of MedicineNew HavenCTUSA
- Yale Microbial Sciences InstituteWest HavenCTUSA
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12
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Pearce VH, Groisman EA, Townsend GE. Dietary sugars silence the master regulator of carbohydrate utilization in human gut Bacteroides species. Gut Microbes 2023; 15:2221484. [PMID: 37358144 PMCID: PMC10294740 DOI: 10.1080/19490976.2023.2221484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 05/08/2023] [Indexed: 06/27/2023] Open
Abstract
The mammalian gut microbiota is a critical human health determinant with therapeutic potential for remediation of many diseases. The host diet is a key factor governing the gut microbiota composition by altering nutrient availability and supporting the expansion of distinct microbial populations. Diets rich in simple sugars modify the abundance of microbial subsets, enriching for microbiotas that elicit pathogenic outcomes. We previously demonstrated that diets rich in fructose and glucose can reduce the fitness and abundance of a human gut symbiont, Bacteroides thetaiotaomicron, by silencing the production of a critical intestinal colonization protein, called Roc, via its mRNA leader through an unknown mechanism. We have now determined that dietary sugars silence Roc by reducing the activity of BT4338, a master regulator of carbohydrate utilization. Here, we demonstrate that BT4338 is required for Roc synthesis, and that BT4338 activity is silenced by glucose or fructose. We show that the consequences of glucose and fructose on orthologous transcription factors are conserved across human intestinal Bacteroides species. This work identifies a molecular pathway by which a common dietary additive alters microbial gene expression in the gut that could be harnessed to modulate targeted microbial populations for future therapeutic interventions.
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Affiliation(s)
- Victoria H. Pearce
- Biochemistry & Molecular Biology, Penn State College of Medicine, Hershey, PA, USA
- Penn State Microbiome Center, Pennsylvania State University, State College, PA, USA
- Center for Molecular Carcinogenesis and Toxicology, Pennsylvania State University, State College, PA, USA
| | - Eduardo A. Groisman
- Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA
- Microbial Sciences Institute, Yale University, New Haven, CT, USA
| | - Guy E. Townsend
- Biochemistry & Molecular Biology, Penn State College of Medicine, Hershey, PA, USA
- Penn State Microbiome Center, Pennsylvania State University, State College, PA, USA
- Center for Molecular Carcinogenesis and Toxicology, Pennsylvania State University, State College, PA, USA
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13
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The Species of Gut Bacteria Associated with Antitumor Immunity in Cancer Therapy. Cells 2022; 11:cells11223684. [PMID: 36429112 PMCID: PMC9688644 DOI: 10.3390/cells11223684] [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: 09/11/2022] [Revised: 10/30/2022] [Accepted: 11/16/2022] [Indexed: 11/22/2022] Open
Abstract
Both preclinical and clinical studies have demonstrated that the modulation of gut microbiota could be a promising strategy for enhancing antitumor immune responses and reducing resistance to immunotherapy in cancer. Various mechanisms, including activation of pattern recognition receptors, gut commensals-produced metabolites and antigen mimicry, have been revealed. Different gut microbiota modulation strategies have been raised, such as fecal microbiota transplantation, probiotics, and dietary selection. However, the identification of gut bacteria species that are either favorable or unfavorable for cancer therapy remains a major challenge. Herein, we summarized the findings related to gut microbiota species observed in the modulation of antitumor immunity. We also discussed the different mechanisms underlying different gut bacteria's functions and the potential applications of these bacteria to cancer immunotherapy in the future.
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Rangarajan AA, Chia HE, Azaldegui CA, Olszewski MH, Pereira GV, Koropatkin NM, Biteen JS. Ruminococcus bromii enables the growth of proximal Bacteroides thetaiotaomicron by releasing glucose during starch degradation. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 35471195 DOI: 10.1099/mic.0.001180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Complex carbohydrates shape the gut microbiota, and the collective fermentation of resistant starch by gut microbes positively affects human health through enhanced butyrate production. The keystone species Ruminococcus bromii (Rb) is a specialist in degrading resistant starch; its degradation products are used by other bacteria including Bacteroides thetaiotaomicron (Bt). We analysed the metabolic and spatial relationships between Rb and Bt during potato starch degradation and found that Bt utilizes glucose that is released from Rb upon degradation of resistant potato starch and soluble potato amylopectin. Additionally, we found that Rb produces a halo of glucose around it when grown on solid media containing potato amylopectin and that Bt cells deficient for growth on potato amylopectin (∆sus Bt) can grow within the halo. Furthermore, when these ∆sus Bt cells grow within this glucose halo, they have an elongated cell morphology. This long-cell phenotype depends on the glucose concentration in the solid media: longer Bt cells are formed at higher glucose concentrations. Together, our results indicate that starch degradation by Rb cross-feeds other bacteria in the surrounding region by releasing glucose. Our results also elucidate the adaptive morphology of Bt cells under different nutrient and physiological conditions.
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Affiliation(s)
| | - Hannah E Chia
- Program in Chemical Biology, University of Michigan, Ann Arbor, Michigan, USA
| | | | - Monica H Olszewski
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, USA
| | - Gabriel V Pereira
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Nicole M Koropatkin
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Julie S Biteen
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, USA.,Program in Chemical Biology, University of Michigan, Ann Arbor, Michigan, USA
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15
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Exploring the Meta-regulon of the CRP/FNR Family of Global Transcriptional Regulators in a Partial-Nitritation Anammox Microbiome. mSystems 2021; 6:e0090621. [PMID: 34636676 PMCID: PMC8510549 DOI: 10.1128/msystems.00906-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Microorganisms must respond to environmental changes to survive, often by controlling transcription initiation. Intermittent aeration during wastewater treatment presents a cyclically changing environment to which microorganisms must react. We used an intermittently aerated bioreactor performing partial nitritation and anammox (PNA) to investigate how the microbiome responds to recurring change. Meta-transcriptomic analysis revealed a dramatic disconnect between the relative DNA abundance and gene expression within the metagenome-assembled genomes (MAGs) of community members, suggesting the importance of transcriptional regulation in this microbiome. To explore how community members responded to cyclic aeration via transcriptional regulation, we searched for homologs of the catabolite repressor protein/fumarate and nitrate reductase regulatory protein (CRP/FNR) family of transcription factors (TFs) within the MAGs. Using phylogenetic analyses, evaluation of sequence conservation in important amino acid residues, and prediction of genes regulated by TFs in the MAGs, we identified homologs of the oxygen-sensing FNR in Nitrosomonas and Rhodocyclaceae, nitrogen-sensing dissimilative nitrate respiration regulator that responds to nitrogen species (DNR) in Rhodocyclaceae, and nitrogen-sensing nitrite and nitric oxide reductase regulator that responds to nitrogen species (NnrR) in Nitrospira MAGs. Our data also predict that CRP/FNR homologs in Ignavibacteria, Flavobacteriales, and Saprospiraceae MAGs sense carbon availability. In addition, a CRP/FNR homolog in a Brocadia MAG was most closely related to CRP TFs known to sense carbon sources in well-studied organisms. However, we predict that in autotrophic Brocadia, this TF most likely regulates a diverse set of functions, including a response to stress during the cyclic aerobic/anoxic conditions. Overall, this analysis allowed us to define a meta-regulon of the PNA microbiome that explains functions and interactions of the most active community members. IMPORTANCE Microbiomes are important contributors to many ecosystems, including ones where nutrient cycling is stimulated by aeration control. Optimizing cyclic aeration helps reduce energy needs and maximize microbiome performance during wastewater treatment; however, little is known about how most microbial community members respond to these alternating conditions. We defined the meta-regulon of a PNA microbiome by combining existing knowledge of how the CRP/FNR family of bacterial TFs respond to stimuli, with metatranscriptomic analyses to characterize gene expression changes during aeration cycles. Our results indicated that, for some members of the community, prior knowledge is sufficient for high-confidence assignments of TF function, whereas other community members have CRP/FNR TFs for which inferences of function are limited by lack of prior knowledge. This study provides a framework to begin elucidating meta-regulons in microbiomes, where pure cultures are not available for traditional transcriptional regulation studies. Defining the meta-regulon can help in optimizing microbiome performance.
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16
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Gardner JG, Schreier HJ. Unifying themes and distinct features of carbon and nitrogen assimilation by polysaccharide-degrading bacteria: a summary of four model systems. Appl Microbiol Biotechnol 2021; 105:8109-8127. [PMID: 34611726 DOI: 10.1007/s00253-021-11614-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 09/20/2021] [Accepted: 09/21/2021] [Indexed: 11/24/2022]
Abstract
Our current understanding of enzymatic polysaccharide degradation has come from a huge number of in vitro studies with purified enzymes. While this vast body of work has been invaluable in identifying and characterizing novel mechanisms of action and engineering desirable traits into these enzymes, a comprehensive picture of how these enzymes work as part of a native in vivo system is less clear. Recently, several model bacteria have emerged with genetic systems that allow for a more nuanced study of carbohydrate active enzymes (CAZymes) and how their activity affects bacterial carbon metabolism. With these bacterial model systems, it is now possible to not only study a single nutrient system in isolation (i.e., carbohydrate degradation and carbon metabolism), but also how multiple systems are integrated. Given that most environmental polysaccharides are carbon rich but nitrogen poor (e.g., lignocellulose), the interplay between carbon and nitrogen metabolism in polysaccharide-degrading bacteria can now be studied in a physiologically relevant manner. Therefore, in this review, we have summarized what has been experimentally determined for CAZyme regulation, production, and export in relation to nitrogen metabolism for two Gram-positive (Caldicellulosiruptor bescii and Clostridium thermocellum) and two Gram-negative (Bacteroides thetaiotaomicron and Cellvibrio japonicus) polysaccharide-degrading bacteria. By comparing and contrasting these four bacteria, we have highlighted the shared and unique features of each, with a focus on in vivo studies, in regard to carbon and nitrogen assimilation. We conclude with what we believe are two important questions that can act as guideposts for future work to better understand the integration of carbon and nitrogen metabolism in polysaccharide-degrading bacteria. KEY POINTS: • Regardless of CAZyme deployment system, the generation of a local pool of oligosaccharides is a common strategy among Gram-negative and Gram-positive polysaccharide degraders as a means to maximally recoup the energy expenditure of CAZyme production and export. • Due to the nitrogen deficiency of insoluble polysaccharide-containing substrates, Gram-negative and Gram-positive polysaccharide degraders have a diverse set of strategies for supplementation and assimilation. • Future work needs to precisely characterize the energetic expenditures of CAZyme deployment and bolster our understanding of how carbon and nitrogen metabolism are integrated in both Gram-negative and Gram-positive polysaccharide-degrading bacteria, as both of these will significantly influence a given bacterium's suitability for biotechnology applications.
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Affiliation(s)
- Jeffrey G Gardner
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD, USA.
| | - Harold J Schreier
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD, USA.,Department of Marine Biotechnology, Institute of Marine and Environmental Technology, University of Maryland, Baltimore County, Baltimore, MD, USA
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17
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Briggs JA, Grondin JM, Brumer H. Communal living: glycan utilization by the human gut microbiota. Environ Microbiol 2020; 23:15-35. [PMID: 33185970 DOI: 10.1111/1462-2920.15317] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 11/06/2020] [Accepted: 11/09/2020] [Indexed: 12/15/2022]
Abstract
Our lower gastrointestinal tract plays host to a vast consortium of microbes, known as the human gut microbiota (HGM). The HGM thrives on a complex and diverse range of glycan structures from both dietary and host sources, the breakdown of which requires the concerted action of cohorts of carbohydrate-active enzymes (CAZymes), carbohydrate-binding proteins, and transporters. The glycan utilization profile of individual taxa, whether 'specialist' or 'generalist', is dictated by the number and functional diversity of these glycan utilization systems. Furthermore, taxa in the HGM may either compete or cooperate in glycan deconstruction, thereby creating a complex ecological web spanning diverse nutrient niches. As a result, our diet plays a central role in shaping the composition of the HGM. This review presents an overview of our current understanding of glycan utilization by the HGM on three levels: (i) molecular mechanisms of individual glycan deconstruction and uptake by key bacteria, (ii) glycan-mediated microbial interactions, and (iii) community-scale effects of dietary changes. Despite significant recent advancements, there remains much to be discovered regarding complex glycan metabolism in the HGM and its potential to affect positive health outcomes.
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Affiliation(s)
- Jonathon A Briggs
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Julie M Grondin
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Harry Brumer
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.,Department of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.,Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.,Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
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