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Iron insertion into coproporphyrin III‐ferrochelatase complex: Evidence for an intermediate distorted catalytic species

Understanding the reaction mechanism of enzymes at the molecular level is generally a difficult task, since many parameters affect the turnover. Often, due to high reactivity and formation of transient species or intermediates, detailed information on enzymatic catalysis is obtained by means of mode...

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Detalles Bibliográficos
Autores principales: Gabler, Thomas, Dali, Andrea, Sebastiani, Federico, Furtmüller, Paul Georg, Becucci, Maurizio, Hofbauer, Stefan, Smulevich, Giulietta
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley & Sons, Inc. 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10578119/
https://www.ncbi.nlm.nih.gov/pubmed/37743577
http://dx.doi.org/10.1002/pro.4788
Descripción
Sumario:Understanding the reaction mechanism of enzymes at the molecular level is generally a difficult task, since many parameters affect the turnover. Often, due to high reactivity and formation of transient species or intermediates, detailed information on enzymatic catalysis is obtained by means of model substrates. Whenever possible, it is essential to confirm a reaction mechanism based on substrate analogues or model systems by using the physiological substrates. Here we disclose the ferrous iron incorporation mechanism, in solution, and in crystallo, by the coproporphyrin III‐coproporphyrin ferrochelatase complex from the firmicute, pathogen, and antibiotic resistant, Listeria monocytogenes. Coproporphyrin ferrochelatase plays an important physiological role as the metalation represents the penultimate reaction step in the prokaryotic coproporphyrin‐dependent heme biosynthetic pathway, yielding coproheme (ferric coproporphyrin III). By following the metal titration with resonance Raman spectroscopy and x‐ray crystallography, we prove that upon metalation the saddling distortion becomes predominant both in the crystal and in solution. This is a consequence of the readjustment of hydrogen bond interactions of the propionates with the protein scaffold during the enzymatic catalysis. Once the propionates have established the interactions typical of the coproheme complex, the distortion slowly decreases, to reach the almost planar final product.