Cryo-EM structures of Escherichia coli cytochrome bo₃ reveal bound phospholipids and ubiquinone-8 in a dynamic substrate binding site.

ABSTRACT: Two independent structures of the proton-pumping, respiratory cytochrome bo₃ ubiquinol oxidase (cyt bo₃ ) have been determined by cryogenic electron microscopy (cryo-EM) in styrene-maleic acid (SMA) copolymer nanodiscs and in membrane scaffold protein (MSP) nanodiscs to 2.55- and 2.19-Å resolution, respectively. The structures include the metal redox centers (heme b, heme o₃ , and Cu_B), the redox-active cross-linked histidine-tyrosine cofactor, and the internal water molecules in the proton-conducting D channel. Each structure also contains one equivalent of ubiquinone-8 (UQ8) in the substrate binding site as well as several phospholipid molecules. The isoprene side chain of UQ8 is clamped within a

SUBMITTER: Li J 

PROVIDER: S-EPMC8403832 | biostudies-literature | 2021 Aug

REPOSITORIES: biostudies-literature