Fig. 1.

Cryo-EM structures of the FtsK_αβ-DNA complex. (A) ATP and ATPγS hydrolysis by FtsK_αβ over time. The data points for the α-phosphates of ATP (light red), ATPγS (dark red), and ADP (light and dark blue) were determined from their peak integrals obtained by 1D ³¹P NMR experiments. ATP is fully hydrolyzed into ADP before the first data point, 7 min after nucleotide addition. (B) Representative cryo-EM micrograph of FtsK_αβ-dsDNA + ATPγS. Typical 2D classes (Top). (C) Top views of previous FtsK_αβ crystal structure (PDB ID 2IUU) and FtsK_αβ-dsDNA cryo-EM maps determined here. Only map III.E (translocating state, SI Appendix, Fig. S3) is shown for ATPγS. (D and E) A 3.6-Å resolution cryo-EM map (Left) of the FtsK_αβ-dsDNA + ATPγS complex and refined atomic model (Right). Each subunit is colored differently with the double-stranded DNA in the pore. Shown as a top view, from above the α-ring through which the DNA exits the pore during translocation (D), and as a side view with subunit A removed (E).