Heightened Dynamics of the Oxidized Y48H Variant of Human Cytochrome <i>c</i> Increases Its Peroxidatic Activity

Deacon, Oliver M.; Karsisiotis, Andreas Ioannis; Moreno-Chicano, T.; Hough, Michael A.; Macdonald, Colin; Blumenschein, Tharin M. A.; Wilson, Michael T.; Moore, Geoffrey R.; Worrall, J.A.R.

doi:10.1021/acs.biochem.7b00890

Cited by 44 publications

(121 citation statements)

References 84 publications

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“…In contrast, recent studies of azide binding to human WT cyt c have revealed a slower Met80 dissociation process with k 1 = 5.77±1.5 s −1 , 67 which is accelerated by mutations in the Ω-loop C (residues 40–57) of the protein. 68 …”

Section: Resultsmentioning

confidence: 99%

Ligation and Reactivity of Methionine-Oxidized Cytochrome c

Zhong

Pletneva

2018

Inorg. Chem.

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Met80, one of the heme iron ligands in cytochrome c (cyt c) is readily oxidized to Met sulfoxide (Met-SO) by several biologically-relevant oxidants. The modification has been suggested to impact both the electron-transfer (ET) and apoptotic functions of this metalloprotein. The coordination of the heme iron in Met-oxidized cyt c (Met-SO cyt c) is critical for both of these functions but has remained poorly defined. We present electronic absorption, NMR, and EPR spectroscopic investigations as well kinetic studies and mutational analyses to identify the heme iron ligands in yeast iso-1 Met-SO cyt c. Similar to the alkaline form of native cyt c, Lys73 and Lys79 ligate to the ferric heme iron in the Met80-oxidized protein but this coordination takes place at much lower pH. The ferrous heme iron is ligated by Met-SO implying the redox-linked ligand switch in the modified protein. Binding studies with a model peptide microperoxidase-8 provide a rationale for alterations in ligation and for the role of the polypeptide packing in native and Met-SO cyt c. Imidazole binding experiments have revealed that Lys dissociation from the ferric heme in K73A/K79G/M80K (M80K#) and Met-SO is more than three orders of magnitude slower than the opening of the heme pocket that limits Met80 replacement in native cyt c. The Lys-to-Met-SO ligand substitution gates ET of ferric Met-SO cyt c with Co(terpy)22+. Owing to the slow Lys dissociation step, ET reaction is slow but possible, which is not the case for non-switchable M80A and M80K#. Acidic conditions cause Lys replacement by a water ligand in Met-SO cyt c (pKa=6.3±0.1) increasing intrinsic peroxidase activity of the protein. This pH-driven ligand switch may be a mechanism to boost peroxidase function of cyt c specifically in apoptotic cells.

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Section: Resultsmentioning

confidence: 99%

Ligation and Reactivity of Methionine-Oxidized Cytochrome c

Zhong

Pletneva

2018

Inorg. Chem.

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“…Remarkably, all the tested alterations of Ser47 resulted in an inefficient caspase activator . Moreover, the G41S and Y48H mutants, which are responsible for the onset of the thrombocytopenia‐4 disease, showed enhanced caspase‐3 activation activity .…”

Section: Cytochrome C In the Cytoplasm: Established And New Targetsmentioning

confidence: 96%

New moonlighting functions of mitochondrial cytochrome c in the cytoplasm and nucleus

et al. 2019

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Cytochrome c (Cc) is a protein that functions as an electron carrier in the mitochondrial respiratory chain. However, Cc has moonlighting roles outside mitochondria driving the transition of apoptotic cells from life to death. When living cells are damaged, Cc escapes its natural mitochondrial environment and, once in the cytosol, it binds other proteins to form a complex named the apoptosome—a platform that triggers caspase activation and further leads to controlled cell dismantlement. Early released Cc also binds to inositol 1,4,5‐triphosphate receptors on the ER membrane, which stimulates further massive Cc release from mitochondria. Besides the well‐characterized binding proteins contributing to the proapoptotic functions of Cc, many novel protein targets have been recently described. Among them, histone chaperones were identified as key partners of Cc following DNA breaks, indicating that Cc might modulate chromatin dynamics through competitive binding to histone chaperones. In this article, we review the ample set of recently discovered antiapoptotic proteins—involved in DNA damage, transcription, and energetic metabolism—reported to interact with Cc in the cytoplasm and even the nucleus upon DNA breaks.

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“…The replacement of Tyr48 by the positively charged histidine caused several functional changes, including reduced oxygen consumption rate and increased apoptosis (63). A recent study on the Tyr48His variant showed that the pentacoordinated form of Cytc, which promotes cardiolipin peroxidase activity, is more prevalent in the mutant, further supporting the increased apoptotic activity (71). Molecular dynamics simulations concluded that both Gly41Ser and Tyr48His mutations result in a less stable and more open protein structure, which would promote cardiolipin peroxidase activity (72).…”

Section: Tyr48 Phosphorylationmentioning

confidence: 98%

Tissue‐specific regulation of cytochrome c by post‐translational modifications: respiration, the mitochondrial membrane potential, ROS, and apoptosis

et al. 2018

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Cytochrome c (Cytc) plays a vital role in the mitochondrial electron transport chain (ETC). In addition, it is a key regulator of apoptosis. Cytc has multiple other functions including ROS production and scavenging, cardiolipin peroxidation, and mitochondrial protein import. Cytc is tightly regulated by allosteric mechanisms, tissue‐specific isoforms, and post‐translational modifications (PTMs). Distinct residues of Cytc are modified by PTMs, primarily phosphorylations, in a highly tissue‐specific manner. These modifications downregulate mitochondrial ETC flux and adjust the mitochondrial membrane potential (ΔΨm), to minimize reactive oxygen species (ROS) production under normal conditions. In pathologic and acute stress conditions, such as ischemia–reperfusion, phosphorylations are lost, leading to maximum ETC flux, ΔΨm hyperpolarization, excessive ROS generation, and the release of Cytc. It is also the dephosphorylated form of the protein that leads to maximum caspase activation. We discuss the complex regulation of Cytc and propose that it is a central regulatory step of the mammalian ETC that can be rate limiting in normal conditions. This regulation is important because it maintains optimal intermediate ΔΨm, limiting ROS generation. We examine the role of Cytc PTMs, including phosphorylation, acetylation, methylation, nitration, nitrosylation, and sulfoxidation and consider their potential biological significance by evaluating their stoichiometry.—Kalpage, H. A., Bazylianska, V., Recanati, M. A., Fite, A., Liu, J., Wan, J., Mantena, N., Malek, M. H., Podgorski, I., Heath, E. I., Vaishnav, A., Edwards, B. F., Grossman, L. I., Sanderson, T. H., Lee, I., Hüttemann, M. Tissue‐specific regulation of cytochrome c by post‐translational modifications: respiration, the mitochondrial membrane potential, ROS, and apoptosis. FASEB J. 33, 1540–1553 (2019). http://www.fasebj.org

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Heightened Dynamics of the Oxidized Y48H Variant of Human Cytochrome c Increases Its Peroxidatic Activity

Cited by 44 publications

References 84 publications

Ligation and Reactivity of Methionine-Oxidized Cytochrome c

Ligation and Reactivity of Methionine-Oxidized Cytochrome c

New moonlighting functions of mitochondrial cytochrome c in the cytoplasm and nucleus

Tissue‐specific regulation of cytochrome c by post‐translational modifications: respiration, the mitochondrial membrane potential, ROS, and apoptosis

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