Fig. 3: Crystal structure analysis of the CanA monomer.

a crystal structure of the CanA monomer (cyan) depicted as a ribbon diagram. The arrow indicates a rendering of the disordered loop region 34–40; b close-up of the superposed CanA monomer from the crystal structure (blue) with the cryoEM CanA protomer (tan) depicting the conformational change within the loop region 161–173; c close-up of the RMSD rendering from a Matchmaker backbone alignment between the CanA protomer and monomer that highlights the difference in loop region 161–173; d alignment of the CanA monomer from the crystal structure (blue) to an interacting axial pair of CanA protomers from the cryoEM structure. The N-terminal donor strand from protomer i (violet) inserts into the acceptor groove of protomer j (tan); e, f zoomed-in views of loop region 161–173 in the CanA cryoEM structure (e) and the superposed CanA monomer (f). The latter view revealed a potential steric clash (arrow) between this region of the CanA crystal structure with donor strand residues Tyr11 to Ser20 that potentially precludes CanA oligomerization in the absence of calcium ion binding.