Cryo-EM structures of Cereibacter sphaeroides ferrochelatase reveal an oligomeric state that occludes the substrate-binding site

Cryo-EM structures of Cereibacter sphaeroides ferrochelatase (PpfCCs) reveal a homotetrameric state that occludes PPIX binding, with 2.5 Å resolution for the wild-type enzyme.

• Why it matters: The heme/(bacterio)chlorophyll branchpoint requires tight control of PPIX flux, especially in facultative phototrophic bacteria that switch between respiratory and photosynthetic growth.
• What they did: Using cryogenic electron microscopy, the authors solved 2.6 Å and 2.5 Å structures of an active-site mutant and the wild-type enzyme, respectively, and analyzed oligomeric interfaces and active-site accessibility.
• The result: The mutant forms a dimer coordinating two hemes, while the wild-type forms a homotetramer where active sites are occluded, suggesting a transient inactive regulatory state that could modulate tetrapyrrole flux.

AI summary of the abstract · may contain errors · not medical advice · read the paper.