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Communication

Structural Rearrangements of a Dodecameric Ketol-Acid Reductoisomerase Isolated from a Marine Thermophilic Methanogen

1
Microbial Metabolism Research Group, Max Planck Institute for Marine Microbiology, Celsiusstraße 1, 28359 Bremen, Germany
2
Core Facility for Mass Spectrometry & Proteomics, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Straße 10, 35043 Marburg, Germany
*
Author to whom correspondence should be addressed.
Academic Editor: Victoria Bunik
Biomolecules 2021, 11(11), 1679; https://doi.org/10.3390/biom11111679
Received: 14 October 2021 / Revised: 5 November 2021 / Accepted: 8 November 2021 / Published: 11 November 2021
(This article belongs to the Special Issue Supramolecular Protein Structures)
Ketol-acid reductoisomerase (KARI) orchestrates the biosynthesis of branched-chain amino acids, an elementary reaction in prototrophic organisms as well as a valuable process in biotechnology. Bacterial KARIs belonging to class I organise as dimers or dodecamers and were intensively studied to understand their remarkable specificity towards NADH or NADPH, but also to develop antibiotics. Here, we present the first structural study on a KARI natively isolated from a methanogenic archaea. The dodecameric structure of 0.44-MDa was obtained in two different conformations, an open and close state refined to a resolution of 2.2-Å and 2.1-Å, respectively. These structures illustrate the conformational movement required for substrate and coenzyme binding. While the close state presents the complete NADP bound in front of a partially occupied Mg2+-site, the Mg2+-free open state contains a tartrate at the nicotinamide location and a bound NADP with the adenine-nicotinamide protruding out of the active site. Structural comparisons show a very high conservation of the active site environment and detailed analyses point towards few specific residues required for the dodecamerisation. These residues are not conserved in other dodecameric KARIs that stabilise their trimeric interface differently, suggesting that dodecamerisation, the cellular role of which is still unknown, might have occurred several times in the evolution of KARIs. View Full-Text
Keywords: ketol-acid reductoisomerases; methanogenic archaea; X-ray crystallography; conformational rearrangement; native purification; oligomerisation ketol-acid reductoisomerases; methanogenic archaea; X-ray crystallography; conformational rearrangement; native purification; oligomerisation
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MDPI and ACS Style

Lemaire, O.N.; Müller, M.-C.; Kahnt, J.; Wagner, T. Structural Rearrangements of a Dodecameric Ketol-Acid Reductoisomerase Isolated from a Marine Thermophilic Methanogen. Biomolecules 2021, 11, 1679. https://doi.org/10.3390/biom11111679

AMA Style

Lemaire ON, Müller M-C, Kahnt J, Wagner T. Structural Rearrangements of a Dodecameric Ketol-Acid Reductoisomerase Isolated from a Marine Thermophilic Methanogen. Biomolecules. 2021; 11(11):1679. https://doi.org/10.3390/biom11111679

Chicago/Turabian Style

Lemaire, Olivier N., Marie-Caroline Müller, Jörg Kahnt, and Tristan Wagner. 2021. "Structural Rearrangements of a Dodecameric Ketol-Acid Reductoisomerase Isolated from a Marine Thermophilic Methanogen" Biomolecules 11, no. 11: 1679. https://doi.org/10.3390/biom11111679

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