Figure 2: Architecture and Stoichiometry of the E. coli DNA Helicase•Bacteriophage λP Complex
(A) Experimental EM density map of the E. coli DnaB helicase•bacteriophage λP complex. (B) Same as panel A except that the map has been rotated by 90°. (C) The E. coli DnaB helicase•bacteriophage λP complex depicting the ruptured interface between DnaB subunits A and B, and the deep canyon that runs through the complex. The complex has been sub-divided into three tiers: λP loader (individual chains are colored in shades of orange), the DnaB CTD (colored in alternating blue and cyan), and the DnaB NTD tiers (colored in alternating dark and light gray). The DnaB CTD-NTD linker helix (residues 182-202) is colored yellow and the DnaB CTD helix (residues 291-302) that is involved in λP binding interactions is colored green. (D) Same as panel C except that the model has been rotated by 90°. The five λPmolecules in the complex are labeled λP1 (chain Z), λP2 (chain Y), λP3 (chain X), λP4 (chain W), and λP5 (chain V).