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. Author manuscript; available in PMC: 2022 Jun 20.
Published in final edited form as: Nat Chem Biol. 2021 Dec 20;18(1):101–108. doi: 10.1038/s41589-021-00935-y

Extended Data Fig. 1. Topological map of CcsBA and proposed method of apocytc heme attachment.

Extended Data Fig. 1

a. Schematic of H. hepaticus CcsBA topology catalyzing heme attachment to apocytc. CcsBA consists of fourteen transmembrane domains and two major periplasmic domains. Conserved features are shown: two conserved histidines in the transmembrane domain (TM-His1-H858, TM-His2-H83) and two conserved periplasmic histidines (P-His1-H897, P-His2-H761) which flank the heme-handling WWD domain. The WWD domain positions heme for attachment to the CXXCH motif in apocytochrome c to form holocytc. Heme enters through a vestibule and is liganded by the TM-His1 and TM-His2. Exact, conserved substitutions and semi-conserved substitutions are all colored in red (T-Coffee analysis1) derived from comparing organisms: M. tuberculosis, B. pertussis, Synechocystis, B. theta, B. subtilis, Wolinella, and H. hepaticus. b. Chemistry of thioether formation. Modified from3. Red arrows indicate two electron transfer.