Mitochondrial Aconitase Modification, Functional Inhibition, and Evidence for a Supramolecular Complex of the TCA Cycle by the Renal Toxicant S-(1,1,2,2-Tetrafluoroethyl)-L
详细信息 查看全文
- 作者：Eric A. James ; Steven P. Gygi ; Michael L. Adams ; Robert H. Pierce ; Nelson Fausto ; Ruedi H. Aebersold ; Sidney D. Nelson ; and Sam A. Bruschi
- 刊名：Biochemistry
- 出版年：2002
- 出版时间：May 28, 2002
- 年：2002
- 卷：41
- 期：21
- 页码：6789 - 6797
- 全文大小：203K
- 年卷期：v.41,no.21(May 28, 2002)
- ISSN：1520-4995
文摘
Metabolism of the common industrial gas tetrafluoroethylene in mammals results in theformation of S-(1,1,2,2)-tetrafluoroethyl-L-cysteine (TFEC), which can be bioactivated by a mitochondrialC-S lyase commonly referred to as 
-lyase. The resultant "reactive intermediate", difluorothioacetyl fluoride(DFTAF), is a potent thioalkylating and protein-modifying species. Previously, we have identifiedmitochondrial HSP70, HSP60, aspartate aminotransferase, and the E2 and E3 subunits of the 
-ketoglutaratedehydrogenase (KGDH) complex as specific proteins structurally modified during this process. Moreover,functional alterations to the KGDH complex were also detected and implicated in the progression ofinjury. We report here the identification, by tandem mass spectrometry, and functional characterizationof the final remaining major protein species modified by DFTAF, previously designated as P99(unk), asmitochondrial aconitase. Aconitase activity was maximally inhibited by 56.5% in renal homogenates aftera 6 h exposure to TFEC. In comparison to KGDH, aconitase inhibition (up to 79%) in a cell culturemodel for TFEC-mediated cytotoxicity was greater and preceded KGDH inhibition, indicating thataconitase modification may constitute an early event in TFEC-mediated mitochondrial damage and celldeath. These findings largely define the initial lesion of TFEC-mediated cell death and also have implicationsfor the modeling of mitochondrial enzymatic architecture and the localization and identity of renalmitochondrial cysteine S-conjugate -lyase.
-lyase. The resultant "reactive intermediate", difluorothioacetyl fluoride(DFTAF), is a potent thioalkylating and protein-modifying species. Previously, we have identifiedmitochondrial HSP70, HSP60, aspartate aminotransferase, and the E2 and E3 subunits of the -ketoglutaratedehydrogenase (KGDH) complex as specific proteins structurally modified during this process. Moreover,functional alterations to the KGDH complex were also detected and implicated in the progression ofinjury. We report here the identification, by tandem mass spectrometry, and functional characterizationof the final remaining major protein species modified by DFTAF, previously designated as P99(unk), asmitochondrial aconitase. Aconitase activity was maximally inhibited by 56.5% in renal homogenates aftera 6 h exposure to TFEC. In comparison to KGDH, aconitase inhibition (up to 79%) in a cell culturemodel for TFEC-mediated cytotoxicity was greater and preceded KGDH inhibition, indicating thataconitase modification may constitute an early event in TFEC-mediated mitochondrial damage and celldeath. These findings largely define the initial lesion of TFEC-mediated cell death and also have implicationsfor the modeling of mitochondrial enzymatic architecture and the localization and identity of renalmitochondrial cysteine S-conjugate -lyase.