Fig. 2: CpaF_AMPPNP has symmetric open, closed and open’ nucleotide binding pockets that showcase the catalytic cycle.

A The three subunits in the asymmetric unit bind AMPPNP, ADP/Mg²⁺ or ADP, constituting open, closed and open’ active site states, respectively. Each active site is formed by the NTD2 and CTD of subunit n (NTD2_n and CTD_n), and the CTD of subunit n + 1 (CTD_n+1). Zoom window shows surface rendered to electrostatic charge. Blue to red spectrum represent positive to negative charges with units k_BT/e_c. B Superposition of subunits within the asymmetric unit with their neighbouring CTD_n+1. (Left) Comparison of CpaF_AMPPNP open and open’ states. (Right) Comparison of CpaF_AMPPNP open and CpaF_ADP open’ states. CpaF_AMPPNP subunits follow the colour code used in (A). C Analysis of open, closed and open’ active site states with AMPPNP, ADP/Mg²⁺ or ADP alone bound, respectively. The open’ state has a relatively disordered active site with an unstructured P-loop. For clarity, ASP Box E312 has been omitted as well as the distances between E357 and the nucleotide terminal phosphate. Both residues with respective distances are shown in Supplementary Fig. 5.