Figure 5: Comparison of the ATPγS–CMG–DNA structure with available helicase–nucleic acid assemblies.
From: Cryo-EM structures of the eukaryotic replicative helicase bound to a translocation substrate
(a) The Rho termination factor (PDB entry 3ICE) contacts and compresses single-stranded RNA. The RNA structure is compared with one single DNA strand extracted from a B-form double helix. Spheres represent the centre of mass of each nucleotide. (b) The Papillomavirus E1 replicative helicase (PDB entry 2GXA) contacts and compresses single-stranded DNA. (c) The bacterial DnaB replicative helicase contacts and slightly compresses single-stranded DNA (approximating A-form DNA, PDB entry 4ESV). (d) The MCM motor of the CMG harbours a more extended form of single-stranded DNA, which appears to match B-form DNA. The DNA density matches the structure of one single strand in the double helix. This supports the notion that the CMG is a single-stranded DNA translocase.
