Genetic and Biochemical Analysis of Anaerobic Respiration in <named-content content-type="genus-species">Bacteroides fragilis</named-content> and Its Importance <italic toggle="yes">In Vivo</italic>
ABSTRACT In bacteria, the respiratory pathways that drive molecular transport and ATP synthesis include a variety of enzyme complexes that utilize different electron donors and acceptors. This property allows them to vary the efficiency of energy conservation and to generate different types of elect...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
American Society for Microbiology
2020-02-01
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| Series: | mBio |
| Subjects: | |
| Online Access: | https://journals.asm.org/doi/10.1128/mBio.03238-19 |
| _version_ | 1798031985478729728 |
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| author | Takeshi Ito Rene Gallegos Leigh M. Matano Nicole L. Butler Noam Hantman Matthew Kaili Michael J. Coyne Laurie E. Comstock Michael H. Malamy Blanca Barquera |
| author_facet | Takeshi Ito Rene Gallegos Leigh M. Matano Nicole L. Butler Noam Hantman Matthew Kaili Michael J. Coyne Laurie E. Comstock Michael H. Malamy Blanca Barquera |
| author_sort | Takeshi Ito |
| collection | DOAJ |
| description | ABSTRACT In bacteria, the respiratory pathways that drive molecular transport and ATP synthesis include a variety of enzyme complexes that utilize different electron donors and acceptors. This property allows them to vary the efficiency of energy conservation and to generate different types of electrochemical gradients (H+ or Na+). We know little about the respiratory pathways in Bacteroides species, which are abundant in the human gut, and whether they have a simple or a branched pathway. Here, we combined genetics, enzyme activity measurements, and mammalian gut colonization assays to better understand the first committed step in respiration, the transfer of electrons from NADH to quinone. We found that a model gut Bacteroides species, Bacteroides fragilis, has all three types of putative NADH dehydrogenases that typically transfer electrons from the highly reducing molecule NADH to quinone. Analyses of NADH oxidation and quinone reduction in wild-type and deletion mutants showed that two of these enzymes, Na+-pumping NADH:quinone oxidoreductase (NQR) and NADH dehydrogenase II (NDH2), have NADH dehydrogenase activity, whereas H+-pumping NADH:ubiquinone oxidoreductase (NUO) does not. Under anaerobic conditions, NQR contributes more than 65% of the NADH:quinone oxidoreductase activity. When grown in rich medium, none of the single deletion mutants had a significant growth defect; however, the double Δnqr Δndh2 mutant, which lacked almost all NADH:quinone oxidoreductase activity, had a significantly increased doubling time. Despite unaltered in vitro growth, the single nqr deletion mutant was unable to competitively colonize the gnotobiotic mouse gut, confirming the importance of NQR to respiration in B. fragilis and the overall importance of respiration to this abundant gut symbiont. IMPORTANCE Bacteroides species are abundant in the human intestine and provide numerous beneficial properties to their hosts. The ability of Bacteroides species to convert host and dietary glycans and polysaccharides to energy is paramount to their success in the human gut. We know a great deal about the molecules that these bacteria extract from the human gut but much less about how they convert those molecules into energy. Here, we show that B. fragilis has a complex respiratory pathway with two different enzymes that transfer electrons from NADH to quinone and a third enzyme complex that may use an electron donor other than NADH. Although fermentation has generally been believed to be the main mechanism of energy generation in Bacteroides, we found that a mutant lacking one of the NADH:quinone oxidoreductases was unable to compete with the wild type in the mammalian gut, revealing the importance of respiration to these abundant gut symbionts. |
| first_indexed | 2024-04-11T20:06:39Z |
| format | Article |
| id | doaj.art-12244fa6b43343798eb241ea4fed69c0 |
| institution | Directory Open Access Journal |
| issn | 2150-7511 |
| language | English |
| last_indexed | 2024-04-11T20:06:39Z |
| publishDate | 2020-02-01 |
| publisher | American Society for Microbiology |
| record_format | Article |
| series | mBio |
| spelling | doaj.art-12244fa6b43343798eb241ea4fed69c02022-12-22T04:05:18ZengAmerican Society for MicrobiologymBio2150-75112020-02-0111110.1128/mBio.03238-19Genetic and Biochemical Analysis of Anaerobic Respiration in <named-content content-type="genus-species">Bacteroides fragilis</named-content> and Its Importance <italic toggle="yes">In Vivo</italic>Takeshi Ito0Rene Gallegos1Leigh M. Matano2Nicole L. Butler3Noam Hantman4Matthew Kaili5Michael J. Coyne6Laurie E. Comstock7Michael H. Malamy8Blanca Barquera9Center for Biotechnology and Interdisciplinary Sciences, Rensselaer Polytechnic Institute, Troy, New York, USADepartment of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USADivision of Infectious Diseases, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, USACenter for Biotechnology and Interdisciplinary Sciences, Rensselaer Polytechnic Institute, Troy, New York, USACenter for Biotechnology and Interdisciplinary Sciences, Rensselaer Polytechnic Institute, Troy, New York, USADepartment of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USADivision of Infectious Diseases, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, USADivision of Infectious Diseases, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, USADepartment of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USACenter for Biotechnology and Interdisciplinary Sciences, Rensselaer Polytechnic Institute, Troy, New York, USAABSTRACT In bacteria, the respiratory pathways that drive molecular transport and ATP synthesis include a variety of enzyme complexes that utilize different electron donors and acceptors. This property allows them to vary the efficiency of energy conservation and to generate different types of electrochemical gradients (H+ or Na+). We know little about the respiratory pathways in Bacteroides species, which are abundant in the human gut, and whether they have a simple or a branched pathway. Here, we combined genetics, enzyme activity measurements, and mammalian gut colonization assays to better understand the first committed step in respiration, the transfer of electrons from NADH to quinone. We found that a model gut Bacteroides species, Bacteroides fragilis, has all three types of putative NADH dehydrogenases that typically transfer electrons from the highly reducing molecule NADH to quinone. Analyses of NADH oxidation and quinone reduction in wild-type and deletion mutants showed that two of these enzymes, Na+-pumping NADH:quinone oxidoreductase (NQR) and NADH dehydrogenase II (NDH2), have NADH dehydrogenase activity, whereas H+-pumping NADH:ubiquinone oxidoreductase (NUO) does not. Under anaerobic conditions, NQR contributes more than 65% of the NADH:quinone oxidoreductase activity. When grown in rich medium, none of the single deletion mutants had a significant growth defect; however, the double Δnqr Δndh2 mutant, which lacked almost all NADH:quinone oxidoreductase activity, had a significantly increased doubling time. Despite unaltered in vitro growth, the single nqr deletion mutant was unable to competitively colonize the gnotobiotic mouse gut, confirming the importance of NQR to respiration in B. fragilis and the overall importance of respiration to this abundant gut symbiont. IMPORTANCE Bacteroides species are abundant in the human intestine and provide numerous beneficial properties to their hosts. The ability of Bacteroides species to convert host and dietary glycans and polysaccharides to energy is paramount to their success in the human gut. We know a great deal about the molecules that these bacteria extract from the human gut but much less about how they convert those molecules into energy. Here, we show that B. fragilis has a complex respiratory pathway with two different enzymes that transfer electrons from NADH to quinone and a third enzyme complex that may use an electron donor other than NADH. Although fermentation has generally been believed to be the main mechanism of energy generation in Bacteroides, we found that a mutant lacking one of the NADH:quinone oxidoreductases was unable to compete with the wild type in the mammalian gut, revealing the importance of respiration to these abundant gut symbionts.https://journals.asm.org/doi/10.1128/mBio.03238-19Bacteroides fragilisrespirationNQRgut microbiota |
| spellingShingle | Takeshi Ito Rene Gallegos Leigh M. Matano Nicole L. Butler Noam Hantman Matthew Kaili Michael J. Coyne Laurie E. Comstock Michael H. Malamy Blanca Barquera Genetic and Biochemical Analysis of Anaerobic Respiration in <named-content content-type="genus-species">Bacteroides fragilis</named-content> and Its Importance <italic toggle="yes">In Vivo</italic> mBio Bacteroides fragilis respiration NQR gut microbiota |
| title | Genetic and Biochemical Analysis of Anaerobic Respiration in <named-content content-type="genus-species">Bacteroides fragilis</named-content> and Its Importance <italic toggle="yes">In Vivo</italic> |
| title_full | Genetic and Biochemical Analysis of Anaerobic Respiration in <named-content content-type="genus-species">Bacteroides fragilis</named-content> and Its Importance <italic toggle="yes">In Vivo</italic> |
| title_fullStr | Genetic and Biochemical Analysis of Anaerobic Respiration in <named-content content-type="genus-species">Bacteroides fragilis</named-content> and Its Importance <italic toggle="yes">In Vivo</italic> |
| title_full_unstemmed | Genetic and Biochemical Analysis of Anaerobic Respiration in <named-content content-type="genus-species">Bacteroides fragilis</named-content> and Its Importance <italic toggle="yes">In Vivo</italic> |
| title_short | Genetic and Biochemical Analysis of Anaerobic Respiration in <named-content content-type="genus-species">Bacteroides fragilis</named-content> and Its Importance <italic toggle="yes">In Vivo</italic> |
| title_sort | genetic and biochemical analysis of anaerobic respiration in named content content type genus species bacteroides fragilis named content and its importance italic toggle yes in vivo italic |
| topic | Bacteroides fragilis respiration NQR gut microbiota |
| url | https://journals.asm.org/doi/10.1128/mBio.03238-19 |
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