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Figure 1
Sequences and structures of the recombinant CRT constructs. (a) CRT modular structure (top) and design of the crystallized construct (below). The GD domain (GD_N and GD_C, green) is fully conserved. In the P domain (magenta), 1 to 3 mark the hairpin sequence repeats. The truncation GSG linker is shown in orange, the small junction domain (J_N and J_C) linking the GD and P domains is in dark blue and the C-terminal His tag is labelled T (grey). (b) Structural alignment of mammalian (human, Hs; mouse, Mm) and parasite (Tc, Eh) CRTs. The identical residues of the `lectin site' are boxed and coloured as in Fig. 3[link]. The residues that are significantly reoriented or displaced in the closed-like EhCRT conformation (Fig. 2[link]) are underlined (red) and the corresponding α1 and β11 secondary structures are indicated below the sequence alignment. The position of the main (P1 to P3, red) and the minor (m1 to m6, magenta) three-dimensional structure variations are indicated below, as well as the interactions (t, u) between the GD and the end of the C-­terminal α-helix (detailed in Supplementary Fig. S1). The aspartic calcium ligand, which is missing in TcCRT, is shown as a red D. TcCRT residue numbering is shown at the top. (c) The truncated P arm adopts various conformations in the superimposed EhCRT monomers. The `closed-like' conformer is shown in blue, the `open' conformers in various green/yellow colours and the linker is in orange. (d) Overall three-dimensional superposition of different CRTs. The same colour code is used as described above. Three different EhCRT open conformers are shown in shades of green. The corresponding PDB codes are 3rg0 (MmCRT; Pocanschi et al., 2011BB34) and 3pos (HsCRT; Chouquet et al., 2011BB9).

IUCrJ
Volume 3| Part 6| November 2016| Pages 408-419
ISSN: 2052-2525
https://doi.org/10.1107/S2052252516012847