Premium
Characterization of heme‐binding properties of Paracoccus denitrificans Surf1 proteins
Author(s) -
Hannappel Achim,
Bundschuh Freya A.,
Ludwig Bernd
Publication year - 2011
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2011.08101.x
Subject(s) - paracoccus denitrificans , heme , heme a , biochemistry , cofactor , cytochrome , hemeprotein , chemistry , cytochrome c oxidase , biology , enzyme
Biogenesis of cytochrome c oxidase (COX) is a highly complex process involving >30 chaperones in eukaryotes; those required for the incorporation of the copper and heme cofactors are also conserved in bacteria. Surf1, associated with heme a insertion and with Leigh syndrome if defective in humans, is present as two homologs in the soil bacterium Paracoccus denitrificans , Surf1c and Surf1q. In an in vitro interaction assay, the heme a transfer from purified heme a synthase, CtaA, to Surf1c was followed, and both Surf proteins were tested for their heme a binding properties. Mutation of four strictly conserved amino acid residues within the transmembrane part of each Surf1 protein confirmed their requirement for heme binding. Interestingly the mutation of a tryptophan residue in transmembrane helix II (W200 in Surf1c and W209 in Surf1q) led to a drastic switch in the heme composition, with Surf1 now being populated mostly by heme o , the intermediate in the heme a biosynthetic pathway. This tryptophan residue discriminates between the two heme moieties, apparently coordinates the formyl group of heme a , and most likely presents the cofactor in a spatial orientation suitable for optimal transfer to its target site within subunit I of cytochrome c oxidase.