A comparison of the fragments containing axial loops pore‐2 and RKH in the crystal structures of the NB domains of LonAs and NB1–2 domains of ClpA and ClpB chaperones. (A) Pore‐2 comprising fragments from EcLon (PDB ID 6N2I, residues 419–445, red), BsLon (PDB ID 3M6A, residues 416–442 with a break between 427 and 437, green), and MtLon (PDB ID 4YPL, residues 417–443, blue) are superimposed onto corresponding fragments from TtClpB (PDB ID 1QVR) of both the NB1 domain (residues 264–295 with a break between 271 and 291, yellow), and the NB2 domain (residues 662–684, orange), as well as with the corresponding fragments from EcClpA (PDB ID 1R6B) of both the NB1 (residues 280–307, pink), and NB2 domains (residues 559–581, magenta); (B) RKH comprising fragments from EcLon (PDB ID 6N2I, residues 447–465, red), BsLon (residues 445–463, green) and MtLon (residues 446–464, blue) are superimposed onto the corresponding fragments from TtClpB of both the NB1 (residues 296–302, yellow) and NB2 domains (residues 686–700, orange), as well as with the corresponding fragments from EcClpA of both the NB1 (residues 308–316, pink), and NB2 domains (residues 582–597, magenta).