Freeman, SL, Skafar, V, Kwon, H, Fielding, AJ, Moody, PCE, Martínez, A, Issoglio, FM, Inchausti, L, Smircich, P, Zeida, A, Piacenza, L, Radi, R and Raven, EL (2022) Crystal structure of Trypanosoma cruzi heme peroxidase and characterization of its substrate specificity and compound I intermediate. Journal of Biological Chemistry, 298 (8). ISSN 0021-9258

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Abstract

The protozoan parasite Trypanosoma cruzi is the causative agent of American trypanosomiasis, otherwise known as Chagas disease. To survive in the host, the T. cruzi parasite needs antioxidant defense systems. One of these is a hybrid heme peroxidase, the T. cruzi ascorbate peroxidase-cytochrome c peroxidase enzyme (TcAPx-CcP). TcAPx-CcP has high sequence identity to members of the class I peroxidase family, notably ascorbate peroxidase (APX) and cytochrome c peroxidase (CcP), as well as a mitochondrial peroxidase from Leishmania major (LmP). The aim of this work was to solve the structure and examine the reactivity of the TcAPx-CcP enzyme. Low temperature electron paramagnetic resonance spectra support the formation of an exchange-coupled [Fe(IV)=O Trp233•+] compound I radical species, analogous to that used in CcP and LmP. We demonstrate that TcAPx-CcP is similar in overall structure to APX and CcP, but there are differences in the substrate-binding regions. Furthermore, the electron transfer pathway from cytochrome c to the heme in CcP and LmP is preserved in the TcAPx-CcP structure. Integration of steady state kinetic experiments, molecular dynamic simulations, and bioinformatic analyses indicates that TcAPx-CcP preferentially oxidizes cytochrome c but is still competent for oxidization of ascorbate. The results reveal that TcAPx-CcP is a credible cytochrome c peroxidase, which can also bind and use ascorbate in host cells, where concentrations are in the millimolar range. Thus, kinetically and functionally TcAPx-CcP can be considered a hybrid peroxidase.

Item Type:	Article
Uncontrolled Keywords:	Chagas disease; ascorbate; cytochrome c; heme; oxidants; peroxidase; Biochemistry & Molecular Biology; 03 Chemical Sciences; 06 Biological Sciences; 11 Medical and Health Sciences
Subjects:	Q Science > QD Chemistry Q Science > QH Natural history > QH301 Biology R Medicine > RM Therapeutics. Pharmacology
Divisions:	Pharmacy & Biomolecular Sciences
Publisher:	Elsevier BV
SWORD Depositor:	A Symplectic
Date Deposited:	26 Aug 2022 09:35
Last Modified:	26 Aug 2022 09:45
DOI or ID number:	10.1016/j.jbc.2022.102204
URI:	https://researchonline.ljmu.ac.uk/id/eprint/17446

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