Revisiting catalytic His and Glu residues in coproporphyrin ferrochelatase - unexpected activities of active site variants.

Autor: Gabler T; Department of Chemistry, Institute of Biochemistry, University of Natural Resources and Life Sciences, Vienna, Austria., Dali A; Department of Chemistry 'Ugo Schiff' (DICUS), University of Florence, Sesto Fiorentino, Italy., Bellei M; Department of Life Sciences, University of Modena and Reggio Emilia, Italy., Sebastiani F; Department of Chemistry 'Ugo Schiff' (DICUS), University of Florence, Sesto Fiorentino, Italy., Becucci M; Department of Chemistry 'Ugo Schiff' (DICUS), University of Florence, Sesto Fiorentino, Italy., Battistuzzi G; Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, Modena, Italy., Furtmüller PG; Department of Chemistry, Institute of Biochemistry, University of Natural Resources and Life Sciences, Vienna, Austria., Smulevich G; Department of Chemistry 'Ugo Schiff' (DICUS), University of Florence, Sesto Fiorentino, Italy.; INSTM Research Unit of Firenze, Sesto Fiorentino, Italy., Hofbauer S; Department of Chemistry, Institute of Biochemistry, University of Natural Resources and Life Sciences, Vienna, Austria.
Jazyk: angličtina
Zdroj: The FEBS journal [FEBS J] 2024 May; Vol. 291 (10), pp. 2260-2272. Date of Electronic Publication: 2024 Feb 23.
DOI: 10.1111/febs.17101
Abstrakt: The identification of the coproporphyrin-dependent heme biosynthetic pathway, which is used almost exclusively by monoderm bacteria in 2015 by Dailey et al. triggered studies aimed at investigating the enzymes involved in this pathway that were originally assigned to the protoporphyrin-dependent heme biosynthetic pathway. Here, we revisit the active site of coproporphyrin ferrochelatase by a biophysical and biochemical investigation using the physiological substrate coproporphyrin III, which in contrast to the previously used substrate protoporphyrin IX has four propionate substituents and no vinyl groups. In particular, we have compared the reactivity of wild-type coproporphyrin ferrochelatase from the firmicute Listeria monocytogenes with those of variants, namely, His182Ala (H182A) and Glu263Gln (E263Q), involving two key active site residues. Interestingly, both variants are active only toward the physiological substrate coproporphyrin III but inactive toward protoporphyrin IX. In addition, E263 exchange impairs the final oxidation step from ferrous coproheme to ferric coproheme. The characteristics of the active site in the context of the residues involved and the substrate binding properties are discussed here using structural and functional means, providing a further contribution to the deciphering of this enigmatic reaction mechanism.
(© 2024 The Authors. The FEBS Journal published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.)
Databáze: MEDLINE
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