Fig. 3

Dehydroxylation pathway for primary BAs CA (R: -OH) and CDCA (R: -H). A The pathway to complete 7α-dehydroxylation is a multi-stage process that involves progressive substrate oxidation, likely for molecule stability, prior to dehydroxylation, followed by reduction at each previously oxidized position along the sterol backbone [59]. The enzyme capable of dehydroxylation, BaiE, is highly conserved structurally between C. scindens (red), C. hylemonae (blue), and P. hiranonis (yellow), evident in both B side and C top-down views of BaiE