BACKGROUND: The mitochondrial carnitine/acylcarnitine carrier (CAC) is essential for cell metabolism since it catalyzes the transport of acylcarnitines into mitochondria allowing the β-oxidation of fatty acids. CAC functional and structural properties have been characterized. Cys residues which could form disulfides suggest the involvement of CAC in redox switches. METHODS: The effect of GSH and GSSG on the [(3)H]-carnitine/carnitine antiport catalyzed by the CAC in proteoliposomes has been studied. The Cys residues involved in the redox switch have been identified by site-directed mutagenesis. Glutathionylated CAC has been assessed by glutathionyl-protein specific antibody. RESULTS: GSH led to increase of transport activity of the CAC extracted from liver mitochondria. A similar effect was observed on the recombinant CAC. The presence of glutaredoxin-1 (Grx1) accelerated the GSH activation of the recombinant CAC. The effect was more evident at 37°C. GSSG led to transport inhibition which was reversed by dithioerythritol (DTE). The effects of GSH and GSSG were studied on CAC Cys-mutants. CAC lacking C136 and C155 was insensitive to both reagents. Mutants containing these two Cys responded as the wild-type. Anti-glutathionyl antibody revealed the formation of glutathionylated CAC. CONCLUSIONS: CAC is redox-sensitive and it is regulated by the GSH/GSSG couple. C136 and C155 are responsible for the regulation which occurs through glutathionylation. GENERAL SIGNIFICANCE: CAC is sensitive to the redox state of the cell switching between oxidized and reduced forms in response to variation of GSSG and GSH concentrations.
BACKGROUND: The mitochondrial carnitine/acylcarnitine carrier (CAC) is essential for cell metabolism since it catalyzes the transport of acylcarnitines into mitochondria allowing the β-oxidation of fatty acids. CAC functional and structural properties have been characterized. Cys residues which could form disulfides suggest the involvement of CAC in redox switches. METHODS: The effect of GSH and GSSG on the [(3)H]-carnitine/carnitine antiport catalyzed by the CAC in proteoliposomes has been studied. The Cys residues involved in the redox switch have been identified by site-directed mutagenesis. Glutathionylated CAC has been assessed by glutathionyl-protein specific antibody. RESULTS:GSH led to increase of transport activity of the CAC extracted from liver mitochondria. A similar effect was observed on the recombinant CAC. The presence of glutaredoxin-1 (Grx1) accelerated the GSH activation of the recombinant CAC. The effect was more evident at 37°C. GSSG led to transport inhibition which was reversed by dithioerythritol (DTE). The effects of GSH and GSSG were studied on CACCys-mutants. CAC lacking C136 and C155 was insensitive to both reagents. Mutants containing these two Cys responded as the wild-type. Anti-glutathionyl antibody revealed the formation of glutathionylated CAC. CONCLUSIONS:CAC is redox-sensitive and it is regulated by the GSH/GSSG couple. C136 and C155 are responsible for the regulation which occurs through glutathionylation. GENERAL SIGNIFICANCE: CAC is sensitive to the redox state of the cell switching between oxidized and reduced forms in response to variation of GSSG and GSH concentrations.
Authors: Ryan J Mailloux; Jian Ying Xuan; Skye McBride; Wael Maharsy; Stephanie Thorn; Chet E Holterman; Christopher R J Kennedy; Peter Rippstein; Robert deKemp; Jean da Silva; Mona Nemer; Marjorie Lou; Mary-Ellen Harper Journal: J Biol Chem Date: 2014-04-12 Impact factor: 5.157
Authors: James Chun Yip Chan; Alex Cheow Khoon Soh; Dorinda Yan Qin Kioh; Jianguo Li; Chandra Verma; Siew Kwan Koh; Roger Wilmer Beuerman; Lei Zhou; Eric Chun Yong Chan Journal: Mol Cell Proteomics Date: 2018-07-13 Impact factor: 5.911