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Publication Abstract from PubMed

Determination of sub-100 kDa (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 experimental approaches, most notably that the alpha/beta domain exhibits structural 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 X-ray crystallography and NMR spectroscopy.

Cryo-EM reveals the structure and dynamics of a 723-residue malate synthase G.,Ho MR, Wu YM, Lu YC, Ko TP, Wu KP J Struct Biol. 2023 Jun;215(2):107958. doi: 10.1016/j.jsb.2023.107958. Epub 2023 , Mar 28. PMID:36997036^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.