Hydrogen peroxide-mediated conversion of coproheme to heme b by HemQ-lessons from the first crystal structure and kinetic studies.

ABSTRACT: Heme biosynthesis in Gram-positive bacteria follows a recently described coproporphyrin-dependent pathway with HemQ catalyzing the decarboxylation of coproheme to heme b. Here we present the first crystal structure of a HemQ (homopentameric coproheme-HemQ from Listeria monocytogenes) at 1.69 Å resolution and the conversion of coproheme to heme b followed by UV-vis and resonance Raman spectroscopy as well as mass spectrometry. The ferric five-coordinated coproheme iron of HemQ is weakly bound by a neutral proximal histidine H174. In the crystal structure of the resting state, the distal Q187 (conserved in Firmicutes HemQ) is H-bonded with propionate p2 and the hydrophobic distal cavity lacks solvent water molecules. Two H₂ O₂ molecules are shown to be necessary for dec

SUBMITTER: Hofbauer S 

PROVIDER: S-EPMC5157759 | biostudies-literature | 2016 Dec

REPOSITORIES: biostudies-literature