Structure-based electron-confurcation mechanism of the Ldh-EtfAB complex
Lactate oxidation with NAD+ as electron acceptor is a highly endergonic reaction. Some anaerobic bacteria overcome the energetic hurdle by flavin-based electron bifurcation/confurcation (FBEB/FBEC) using a lactate dehydrogenase (Ldh) in concert with the electron-transferring proteins EtfA and EtfB....
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| Format: | Article |
| Language: | English |
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eLife Sciences Publications Ltd
2022-06-01
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| Series: | eLife |
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| Online Access: | https://elifesciences.org/articles/77095 |
| _version_ | 1811203583878627328 |
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| author | Kanwal Kayastha Alexander Katsyv Christina Himmrich Sonja Welsch Jan M Schuller Ulrich Ermler Volker Müller |
| author_facet | Kanwal Kayastha Alexander Katsyv Christina Himmrich Sonja Welsch Jan M Schuller Ulrich Ermler Volker Müller |
| author_sort | Kanwal Kayastha |
| collection | DOAJ |
| description | Lactate oxidation with NAD+ as electron acceptor is a highly endergonic reaction. Some anaerobic bacteria overcome the energetic hurdle by flavin-based electron bifurcation/confurcation (FBEB/FBEC) using a lactate dehydrogenase (Ldh) in concert with the electron-transferring proteins EtfA and EtfB. The electron cryo-microscopically characterized (Ldh-EtfAB)2 complex of Acetobacterium woodii at 2.43 Å resolution consists of a mobile EtfAB shuttle domain located between the rigid central Ldh and the peripheral EtfAB base units. The FADs of Ldh and the EtfAB shuttle domain contact each other thereby forming the D (dehydrogenation-connected) state. The intermediary Glu37 and Glu139 may harmonize the redox potentials between the FADs and the pyruvate/lactate pair crucial for FBEC. By integrating Alphafold2 calculations a plausible novel B (bifurcation-connected) state was obtained allowing electron transfer between the EtfAB base and shuttle FADs. Kinetic analysis of enzyme variants suggests a correlation between NAD+ binding site and D-to-B-state transition implicating a 75° rotation of the EtfAB shuttle domain. The FBEC inactivity when truncating the ferredoxin domain of EtfA substantiates its role as redox relay. Lactate oxidation in Ldh is assisted by the catalytic base His423 and a metal center. On this basis, a comprehensive catalytic mechanism of the FBEC process was proposed. |
| first_indexed | 2024-04-12T02:57:46Z |
| format | Article |
| id | doaj.art-e81572dee7df4488a0400afc5d9a5796 |
| institution | Directory Open Access Journal |
| issn | 2050-084X |
| language | English |
| last_indexed | 2024-04-12T02:57:46Z |
| publishDate | 2022-06-01 |
| publisher | eLife Sciences Publications Ltd |
| record_format | Article |
| series | eLife |
| spelling | doaj.art-e81572dee7df4488a0400afc5d9a57962022-12-22T03:50:46ZengeLife Sciences Publications LtdeLife2050-084X2022-06-011110.7554/eLife.77095Structure-based electron-confurcation mechanism of the Ldh-EtfAB complexKanwal Kayastha0https://orcid.org/0000-0001-7910-9743Alexander Katsyv1https://orcid.org/0000-0001-9212-231XChristina Himmrich2Sonja Welsch3Jan M Schuller4Ulrich Ermler5https://orcid.org/0000-0002-9583-1418Volker Müller6https://orcid.org/0000-0001-7955-5508Departments of Molecular Membrane Biology of the Max-Planck-Institut for Biophysics, Frankfurt am Main, GermanyDepartment of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe University, Frankfurt am Main, GermanyDepartment of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe University, Frankfurt am Main, GermanyCentral Electron Microscopy Facility, Max Planck Institute of Biophysics, Frankfurt am Main, GermanySYNMICRO Research Center and Department of Chemistry, Philipps University, Marburg, GermanyDepartments of Molecular Membrane Biology of the Max-Planck-Institut for Biophysics, Frankfurt am Main, GermanyDepartment of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe University, Frankfurt am Main, GermanyLactate oxidation with NAD+ as electron acceptor is a highly endergonic reaction. Some anaerobic bacteria overcome the energetic hurdle by flavin-based electron bifurcation/confurcation (FBEB/FBEC) using a lactate dehydrogenase (Ldh) in concert with the electron-transferring proteins EtfA and EtfB. The electron cryo-microscopically characterized (Ldh-EtfAB)2 complex of Acetobacterium woodii at 2.43 Å resolution consists of a mobile EtfAB shuttle domain located between the rigid central Ldh and the peripheral EtfAB base units. The FADs of Ldh and the EtfAB shuttle domain contact each other thereby forming the D (dehydrogenation-connected) state. The intermediary Glu37 and Glu139 may harmonize the redox potentials between the FADs and the pyruvate/lactate pair crucial for FBEC. By integrating Alphafold2 calculations a plausible novel B (bifurcation-connected) state was obtained allowing electron transfer between the EtfAB base and shuttle FADs. Kinetic analysis of enzyme variants suggests a correlation between NAD+ binding site and D-to-B-state transition implicating a 75° rotation of the EtfAB shuttle domain. The FBEC inactivity when truncating the ferredoxin domain of EtfA substantiates its role as redox relay. Lactate oxidation in Ldh is assisted by the catalytic base His423 and a metal center. On this basis, a comprehensive catalytic mechanism of the FBEC process was proposed.https://elifesciences.org/articles/77095electron bifurcationbioenergeticsflavinlactate dehydrogenaseelectron-transferring flavoproteincryo-EM structure |
| spellingShingle | Kanwal Kayastha Alexander Katsyv Christina Himmrich Sonja Welsch Jan M Schuller Ulrich Ermler Volker Müller Structure-based electron-confurcation mechanism of the Ldh-EtfAB complex eLife electron bifurcation bioenergetics flavin lactate dehydrogenase electron-transferring flavoprotein cryo-EM structure |
| title | Structure-based electron-confurcation mechanism of the Ldh-EtfAB complex |
| title_full | Structure-based electron-confurcation mechanism of the Ldh-EtfAB complex |
| title_fullStr | Structure-based electron-confurcation mechanism of the Ldh-EtfAB complex |
| title_full_unstemmed | Structure-based electron-confurcation mechanism of the Ldh-EtfAB complex |
| title_short | Structure-based electron-confurcation mechanism of the Ldh-EtfAB complex |
| title_sort | structure based electron confurcation mechanism of the ldh etfab complex |
| topic | electron bifurcation bioenergetics flavin lactate dehydrogenase electron-transferring flavoprotein cryo-EM structure |
| url | https://elifesciences.org/articles/77095 |
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