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bioRxiv · 10.1101/2022.08.19.504428

Cryo-EM reveals the structure and dynamics of a 723-residue malate synthase G

Ho, M.-R.·Wu, Y.-M.·Lu, Y.-C.·Ko, T.-P.·Wu, K.-P.
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Abstract

Determination of sub-100 kilodalton (kDa) structures by cryo-electron microscopy (EM) is a longstanding but not straightforward goal. Here, we present a 2.9-[A] cryo-EM structure of a 723-amino acid apo-form malate synthase G (MSG) from Escherichia coli. The cryo-EM structure of the 82-kDa MSG exhibits the same global folding as structures resolved by crystallography and nuclear magnetic resonance (NMR) spectroscopy, and the crystal and cryo-EM structures are indistinguishable. Analyses of MSG dynamics reveal consistent conformational flexibilities among the three structural approaches, most notably that the /{beta} domain exhibits heterogeneity. We observed that sidechains of F453, L454, M629, and E630 residues involved in hosting the cofactor acetyl-CoA and substrate rotate differently between the cryo-EM apo-form and complex crystal structures. Our work demonstrates that the cryo-EM technique can be used to determine structures and conformational heterogeneity of sub-100 kDa biomolecules to a quality as high as that obtained from crystallography and NMR spectroscopy.

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Ho, M.-R., Wu, Y.-M., Lu, Y.-C., Ko, T.-P., Wu, K.-P.. 2022-08-19. Cryo-EM reveals the structure and dynamics of a 723-residue malate synthase G. https://doi.org/10.1101/2022.08.19.504428

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