Fig. 4: Single-loaded MCM complexes.
From: MCM double hexamer loading visualized with human proteins
a, Surface rendering and cut-through view of a hSH loaded onto duplex DNA. The C-terminal ATPase site is shown with nucleotides bound at subunit interfaces. b, A superposition of PS1 pore loops and DNA extracted from hDH and hSH show the same configuration. c, MCM hexamer dimerization changes the path of duplex DNA, leading to untwisting and opening of the double helix. d, Surface rendering of the hMO* structure. e, Surface rendering of the yMO structure highlights a different configuration of the ORC compared with hMO*. ORC6 bridges N-terminal MCM and ORC1–5 in both structures. f, A steric clash obtained by modelling the pre-insertion yOCCM (PDB entry 6WGG) demonstrates that hMO* cannot support recruitment of a second MCM, unlike observations for the yMO complex. g, Truncated and full-length ORC1, CDC6 and CDT1 yield the same hMO* complex, as observed by negative-stain 2D averaging.
