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Figure 3
Structures of the ScpB homologue PYCH_12850 and ToScpAN. (a, b) Structural features of PYCH_12850. (a) Two independent dimers in the crystal (left). The protein forms a homodimer through the N-terminal WHD (nWHD), which is followed by a flexible linker segment and a dangling cWHD (middle and right). The relative positions of the two domains differ in the two dimers. (b) Superposition of PYCH_12850 onto S. pneumoniae ScpB. The nWHDs and cWHDs are separately superposed. The nWHD–nWHD interaction as well as the structures are closely similar. (c)–(f) Structural features of ToScpAN. (c) Overall structure. The structure is composed of four stacked α-helices. Residues 75–94 are disordered and indicated by a dotted line. Shown below is a representation of full-length ToScpA. The C-terminal region forms the cWHD. (d) Structural alignment onto SpScpAΔC. The α-helices are labeled in their order of appearance in the structures. The structures are closely similar but only up to α3. (e) Sequence alignment of ToScpAN and SpScpAΔC. Reflecting the structural difference shown in (d), the sequence between α3 and α4 of ToScpAN is notably different from that between α3 and α5 of SpScpAΔC. (f) Intramolecular hydrophobic interaction of α4 with the rest of the protein. The interacting hydrophobic residues on α4 are shown as sticks and the rest of the protein is shown as an electrostatic surface potential map.

IUCrJ
Volume 7| Part 2| March 2020| Pages 193-206
ISSN: 2052-2525
https://doi.org/10.1107/S2052252519016634