Evidence that the catalytic mechanism of heme a synthase involves the formation of a carbocation stabilized by a conserved glutamate.

ABSTRACT: In eukaryotes and many aerobic prokaryotes, the final step of aerobic respiration is catalyzed by an aa₃-type cytochrome c oxidase, which requires a modified heme cofactor, heme a. The conversion of heme b, the prototypical cellular heme, to heme o and ultimately to heme a requires two modifications, the latter of which is conversion of a methyl group to an aldehyde, catalyzed by heme a synthase (HAS). The N- and C-terminal halves of HAS share homology, and each half contains a heme-binding site. Previous reports indicate that the C-terminal site is occupied by a heme b cofactor. The N-terminal site may function as the substrate (heme o) binding site, although this has not been confirmed experimentally. Here, we assess the role of conserved residues from the N- and C-terminal he

SUBMITTER: Rivett ED 

PROVIDER: S-EPMC10529832 | biostudies-literature | 2023 Aug

REPOSITORIES: biostudies-literature