Researchers fixed the E. coli FrdA-SdhE intermediate via site-specific crosslinking, resolving the structure to 2.6 angstroms (Å). This study identified that SdhE stabilizes an FrdA conformation that likely enables the mechanism of autocatalytic covalent flavinylation. FrdA’s FAD-binding domain and capping domain both interact with SdhE, but structural data revealed a 10.8° difference in their angles. The investigators believe that domain rotation affects flavinylation, showing that enzymes are tuned to catalyze reactions in different ways and that conformational diversity can directly relate to catalytic mechanism diversity.
Sharma, P., et al. “Crystal structure of an assembly intermediate of respiratory Complex II.” Nat. Commun. 9, 274 (2018). DOI:10.1038/s41467-017-02713-8.
Instruments and Facilities Used: Small angle X-ray scattering (SAXS) and diffraction and mass spectrometry analysis using beamline 9-2 at Stanford Synchrotron Radiation Lightsource (SSRL) at SLAC National Accelerator Laboratory (SLAC).
Funding Acknowledgements: Supported by Department of Veterans Affairs (DVA; BX001077 to G.C.) and National Institutes of Health (NIH; GM061606 to G.C. and T.M.I.). G.C. (recipient of a Senior Research Career Scientist award, #IK6B004215 from DVA). Vanderbilt University crystallization facility support: S10 RR026915. Use of Stanford Synchrotron Radiation Lightsource (SSRL), SLAC National Accelerator Laboratory (SLAC), supported by Office of Basic Energy Sciences (OBES), U.S. Department of Energy (DOE) Office of Science, under Contract No. DE-AC02-76SF00515. SSRL Structural Molecular Biology Program supported by Office of Biological and Environmental Research (OBER), DOE Office of Science, and by the NIH National Institute of General Medical Sciences (NIGMS; including P41GM103393).