Archaeal MCM Proteins as an Analog for the Eukaryotic Mcm2–7 Helicase to Reveal Essential Features of Structure and Function

Figure 2

General architecture of MCM proteins. (a) MCM monomers can be subdivided into N- and C-terminal tiers. Each tier can be further subdivided, where the N-terminal half includes subdomains A (red), B (blue), and C (yellow) and the C-terminal domain contains the helicase core (green) and a winged helix domain (magenta). (b) The crystal structures of one subunit of the Methanobacterium thermoautotrophicum MCM N-terminal domain double-hexamer (, PDB: 1LTL), monomeric Sulfolobus solfataricus MCM (SsoMCM, PDB: 3F9V), and monomeric Methanopyrus kandleri MCM2 (MkMCM2, PDB: 3F8T) each illustrate the general architecture with distinct subdomains A, B, C, and a AAA+ ATPase domain. Subdomains A, B, and C consist of a helical bundle (red), a zinc-binding domain (blue), and an oligonucleotide/oligosaccharide- (OB-) binding fold (yellow), respectively. The AAA+ domain architecture has five β-sheets flanked by α-helices. All structure representations of Figure 2 were prepared with the Pymol software package [88].

(a)

(b)