6FIP:
reference: NMR structure of the C-terminal domain of TonB protein from Pseudomonas aeruginosa., Oeemig JS, Ollila OHS, Iwai H, PeerJ. 2018 Aug 27;6:e5412. doi: 10.7717/peerj.5412. eCollection 2018. PMID: 30186676

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).