Fig. 3: Experimental reconstruction of the evolutionary pathway between the DZBB, OB, and SH3 folds.
From: An ancestral fold reveals the evolutionary link between RNA polymerase and ribosomal proteins
A Superimposed structures of the single subunit of design-1 in the DZBB-fold and the OB domain of the ribosomal protein L2 from Thermococcus kodakarensis. B Comparison of the topologies of the DZBB and OB folds. In the OB fold, the non-essential secondary elements α1 and β5 are shown as dashed lines. C Multiple sequence alignment of the DZBB-OB chimeric proteins with the parent DZBB proteins, design-1 and design-2. The identical residues with design-2 are colored purple. The two significantly different segments between design-13 (OB) and design-2 (DZBB) are highlighted in gray. D–G Crystal structures and topological images of (D) design-6, (E) design-13, (F) design-18, and (G) design-24. The flows of the engineering procedures are shown as arrows.
