Structural Biology

A scaffold for small proteins

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Science  30 Mar 2018:
Vol. 359, Issue 6383, pp. 1481-1482
DOI: 10.1126/science.359.6383.1481-f

Reconstruction of atomic-resolution structures in cryo–electron microscopy is limited by the ability to select, align, and average individual particles in the underlying images. Small biomolecules pose a particular challenge because they are hard to distinguish from the surrounding amorphous ice. Liu et al. combined a large, computationally designed protein cage with a small, modular domain containing a protein-binding surface that can be evolved separately to bind other small proteins for structure determination. The cage serves as a rigid scaffold that allows for accurate particle selection and alignment. The 17-kDa protein-binding domain was well resolved in the electron density maps at near-atomic resolution.

Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1718825115 (2018).

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