Fig. 3: Explaining the mechanism of DHCR7 activity enhancement.

A L67 and L426 of DHCR7’s substrate-recognizing domain were engineered. L67V and L426A allow the steroid side chain to expand. The Dhc marked in the yellow and grey stick represented the conformation in the modified SRD and wild-type SRD, respectively. B Left: NADPH located in the wild-type DHCR7. Residues with electron transfer functions are rendered in yellow sticks. Right: NADPH located in the MuBtDHCR7. Residues with electron transfer chain 1 and 2 functions are rendered in red and yellow sticks, respectively. C B-Factor values of SRD of WTBtDHCR7 (black) and MuBtDHCR7 (red) with Dhc complexes in 100 ns. D Free energy calculation for residues within 4 Å of Dhc in the DHCR7’s SRD. The red bar represents wild-type BtDHCR7 (WT-BtDHCR7). The gray bar represents mutant BtDHCR7 (Mu-BtDHCR7). E Y290 and W280 were engineered for shortening Y317-C7/C8 distances. The DHC marked in the yellow and pink stick represented the conformation in the wild-type substrate-binding domain and mutant substrate-binding domain, respectively. F The distances between Y317 and C7/C8 of Dhc. G Free energy calculation for residues within 4 Å of Dhc in the DHCR7’s SBD. The red bar represents WT-BtDHCR7. The gray bar represents mutant Mu-BtDHCR7. Source data are provided as a Source Data file.