Identification and characterization of solvent-filled channels in human ferrochelatase

Amy Elizabeth Medlock, Wided Najahi-Missaoui, Teresa A. Ross, Tamara A. Dailey, Joseph Burch, Jessica R. O'Brien, William N. Lanzilotta, Harry A. Dailey

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Ferrochelatase catalyzes the formation of protoheme from two potentially cytotoxic products, iron and protoporphyrin IX. While much is known from structural and kinetic studies on human ferrochelatase of the dynamic nature of the enzyme during catalysis and the binding of protoporphyrin IX and heme, little is known about how metal is delivered to the active site and how chelation occurs. Analysis of all ferrochelatase structures available to date reveals the existence of several solvent-filled channels that originate at the protein surface and continue to the active site. These channels have been proposed to provide a route for substrate entry, water entry, and proton exit during the catalytic cycle. To begin to understand the functions of these channels, we investigated in vitro and in vivo a number of variants that line these solvent-filled channels. Data presented herein support the role of one of these channels, which originates at the surface residue H240, in the delivery of iron to the active site. Structural studies of the arginyl variant of the conserved residue F337, which resides at the back of the active site pocket, suggest that it not only regulates the opening and closing of active site channels but also plays a role in regulating the enzyme mechanism. These data provide insight into the movement of the substrate and water into and out of the active site and how this movement is coordinated with the reaction mechanism.

Original languageEnglish (US)
Pages (from-to)5422-5433
Number of pages12
JournalBiochemistry
Volume51
Issue number27
DOIs
StatePublished - Jul 10 2012

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Ferrochelatase
Catalytic Domain
Heme
Water
Substrates
Enzymes
Chelation
Catalysis
Protons
Membrane Proteins
Iron
Metals
Water Movements
Kinetics

ASJC Scopus subject areas

  • Biochemistry

Cite this

Medlock, A. E., Najahi-Missaoui, W., Ross, T. A., Dailey, T. A., Burch, J., O'Brien, J. R., ... Dailey, H. A. (2012). Identification and characterization of solvent-filled channels in human ferrochelatase. Biochemistry, 51(27), 5422-5433. https://doi.org/10.1021/bi300598g

Identification and characterization of solvent-filled channels in human ferrochelatase. / Medlock, Amy Elizabeth; Najahi-Missaoui, Wided; Ross, Teresa A.; Dailey, Tamara A.; Burch, Joseph; O'Brien, Jessica R.; Lanzilotta, William N.; Dailey, Harry A.

In: Biochemistry, Vol. 51, No. 27, 10.07.2012, p. 5422-5433.

Research output: Contribution to journalArticle

Medlock, AE, Najahi-Missaoui, W, Ross, TA, Dailey, TA, Burch, J, O'Brien, JR, Lanzilotta, WN & Dailey, HA 2012, 'Identification and characterization of solvent-filled channels in human ferrochelatase', Biochemistry, vol. 51, no. 27, pp. 5422-5433. https://doi.org/10.1021/bi300598g
Medlock AE, Najahi-Missaoui W, Ross TA, Dailey TA, Burch J, O'Brien JR et al. Identification and characterization of solvent-filled channels in human ferrochelatase. Biochemistry. 2012 Jul 10;51(27):5422-5433. https://doi.org/10.1021/bi300598g
Medlock, Amy Elizabeth ; Najahi-Missaoui, Wided ; Ross, Teresa A. ; Dailey, Tamara A. ; Burch, Joseph ; O'Brien, Jessica R. ; Lanzilotta, William N. ; Dailey, Harry A. / Identification and characterization of solvent-filled channels in human ferrochelatase. In: Biochemistry. 2012 ; Vol. 51, No. 27. pp. 5422-5433.
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