Quinone electrophiles selectively adduct "electrophile binding motifs" within cytochrome c

Ashley A. Fisher, Matthew T. Labenski, Srinivas Malladi, Vijay Gokhale, Martina E. Bowen, Rania S. Milleron, Shawn B. Bratton, Terrence J. Monks, Serrine S. Lau

Research output: Contribution to journalArticle

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Abstract

Electrophiles generated endogenously, or via the metabolic bioactivation of drugs and other environmental chemicals, are capable of binding to a variety of nucleophilic sites within proteins. Factors that determine site selective susceptibility to electrophile-mediated post-translational modifications, and the consequences of such alterations, remain largely unknown. To identify and characterize chemical-mediated protein adducts, electrophiles with known toxicity were utilized. Hydroquinone, and its mercapturic acid pathway metabolites, cause renal proximal tubular cell necrosis and nephrocarcinogenicity in rats. The adverse effects of HQ and its thioether metabolites are in part a consequence of their oxidation to the corresponding electrophilic 1,4-benzoquinones (BQ). We now report that BQ and 2-(7V-acetylcystein-S-yl)benzoquinone (NAC-BQ) preferentially bind to solvent-exposed lysine-rich regions within cytochrome c. Furthermore, we have identified specific glutamic acid residues within cytochrome c as novel sites of NAC-BQ adduction. The microenvironment at the site of adduction governs both the initial specificity and the structure of the final adduct. The solvent accessibility and local pKa of the adducted and neighboring amino acids contribute to the selectivity of adduction. Postadduction chemistry subsequently alters the nature of the final adduct. Using molecular modeling, the impact of BQ and NAC-BQ adduction on cytochrome c was visualized, revealing the spatial rearrangement of critical residues necessary for protein-protein interactions. Consequently, BQ-adducted cytochrome c fails to initiate caspase-3 activation in native lysates and also inhibits Apaf-1 oligomerization into an apoptosome complex in a purely reconstituted system. In summary, a combination of mass spectroscopic, molecular modeling, and biochemical approaches confirms that electrophile - protein adducts produce structural alterations that influence biological function.

Original languageEnglish (US)
Pages (from-to)11090-11100
Number of pages11
JournalBiochemistry
Volume46
Issue number39
DOIs
StatePublished - Oct 2 2007

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Benzoquinones
Cytochromes c
Molecular modeling
Metabolites
Proteins
Apoptosomes
Oligomerization
Acetylcysteine
Sulfides
Post Translational Protein Processing
Caspase 3
Lysine
Toxicity
benzoquinone
Rats
Glutamic Acid
Necrosis
Chemical activation
Kidney
Amino Acids

ASJC Scopus subject areas

  • Biochemistry

Cite this

Fisher, A. A., Labenski, M. T., Malladi, S., Gokhale, V., Bowen, M. E., Milleron, R. S., ... Lau, S. S. (2007). Quinone electrophiles selectively adduct "electrophile binding motifs" within cytochrome c. Biochemistry, 46(39), 11090-11100. https://doi.org/10.1021/bi700613w

Quinone electrophiles selectively adduct "electrophile binding motifs" within cytochrome c. / Fisher, Ashley A.; Labenski, Matthew T.; Malladi, Srinivas; Gokhale, Vijay; Bowen, Martina E.; Milleron, Rania S.; Bratton, Shawn B.; Monks, Terrence J.; Lau, Serrine S.

In: Biochemistry, Vol. 46, No. 39, 02.10.2007, p. 11090-11100.

Research output: Contribution to journalArticle

Fisher, AA, Labenski, MT, Malladi, S, Gokhale, V, Bowen, ME, Milleron, RS, Bratton, SB, Monks, TJ & Lau, SS 2007, 'Quinone electrophiles selectively adduct "electrophile binding motifs" within cytochrome c', Biochemistry, vol. 46, no. 39, pp. 11090-11100. https://doi.org/10.1021/bi700613w
Fisher AA, Labenski MT, Malladi S, Gokhale V, Bowen ME, Milleron RS et al. Quinone electrophiles selectively adduct "electrophile binding motifs" within cytochrome c. Biochemistry. 2007 Oct 2;46(39):11090-11100. https://doi.org/10.1021/bi700613w
Fisher, Ashley A. ; Labenski, Matthew T. ; Malladi, Srinivas ; Gokhale, Vijay ; Bowen, Martina E. ; Milleron, Rania S. ; Bratton, Shawn B. ; Monks, Terrence J. ; Lau, Serrine S. / Quinone electrophiles selectively adduct "electrophile binding motifs" within cytochrome c. In: Biochemistry. 2007 ; Vol. 46, No. 39. pp. 11090-11100.
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AU - Bowen, Martina E.

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