5B1N:
reference: Angucycline antibiotic waldiomycin recognizes common structural motif conserved in bacterial histidine kinases., Eguchi Y, Okajima T, Tochio N, Inukai Y, Shimizu R, Ueda S, Shinya S, Kigawa T, Fukamizo T, Igarashi M, Utsumi R, J Antibiot (Tokyo). 2017 Mar;70(3):251-258. doi: 10.1038/ja.2016.151. Epub 2016, Dec 21. PMID: 27999439

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