ジャーナル: Nature / 年: 2022 タイトル: Membrane-anchored HDCR nanowires drive hydrogen-powered CO fixation. 著者: Helge M Dietrich / Ricardo D Righetto / Anuj Kumar / Wojciech Wietrzynski / Raphael Trischler / Sandra K Schuller / Jonathan Wagner / Fabian M Schwarz / Benjamin D Engel / Volker Müller / Jan M Schuller / 要旨: Filamentous enzymes have been found in all domains of life, but the advantage of filamentation is often elusive. Some anaerobic, autotrophic bacteria have an unusual filamentous enzyme for CO ...Filamentous enzymes have been found in all domains of life, but the advantage of filamentation is often elusive. Some anaerobic, autotrophic bacteria have an unusual filamentous enzyme for CO fixation-hydrogen-dependent CO reductase (HDCR)-which directly converts H and CO into formic acid. HDCR reduces CO with a higher activity than any other known biological or chemical catalyst, and it has therefore gained considerable interest in two areas of global relevance: hydrogen storage and combating climate change by capturing atmospheric CO. However, the mechanistic basis of the high catalytic turnover rate of HDCR has remained unknown. Here we use cryo-electron microscopy to reveal the structure of a short HDCR filament from the acetogenic bacterium Thermoanaerobacter kivui. The minimum repeating unit is a hexamer that consists of a formate dehydrogenase (FdhF) and two hydrogenases (HydA2) bound around a central core of hydrogenase Fe-S subunits, one HycB3 and two HycB4. These small bacterial polyferredoxin-like proteins oligomerize through their C-terminal helices to form the backbone of the filament. By combining structure-directed mutagenesis with enzymatic analysis, we show that filamentation and rapid electron transfer through the filament enhance the activity of HDCR. To investigate the structure of HDCR in situ, we imaged T. kivui cells with cryo-electron tomography and found that HDCR filaments bundle into large ring-shaped superstructures attached to the plasma membrane. This supramolecular organization may further enhance the stability and connectivity of HDCR to form a specialized metabolic subcompartment within the cell.
EMPIAR-11058 (タイトル: In situ cryo-electron tomography of T. kivui cells Data size: 373.4 Data #1: Subtomograms of HDCR filament particles at bin2 [subtomograms] Data #2: Subtomograms of T. kivui ribosome particles at bin1 [subtomograms] Data #3: Denoised tomograms of T. kivui FIB-milled cells at bin4 [reconstructed volumes] Data #4: Tilt series of T. kivui FIB-milled cells - session 2020-10-22 [tilt series] Data #5: Tilt series of T. kivui FIB-milled cells - session 2021-02-12 [tilt series] Data #6: Unaligned raw frames of T. kivui FIB-milled cells tilt series - session 2020-10-22 [micrographs - multiframe] Data #7: Unaligned raw frames of T. kivui FIB-milled cells tilt series - session 2021-02-12 [micrographs - multiframe])
エネルギーフィルター - 名称: GIF Quantum LS / エネルギーフィルター - スリット幅: 20 eV
詳細
Dose-symmetric tilt-series were acquired (Hagen et al., 2017), starting at +10 degrees to match the pre-tilt of the lamella (i.e. from -50 to +70 degrees).