S3.18 Redox state of quinone affects Acanthamoeba castellanii mitochondrial uncoupling protein activity through sensitivity to purine nucleotides

Hydroxynonenal, a lipid peroxidation end product, stimulates uncoupling protein activity in Acanthamoeba castellanii mitochondria; the sensitivity of the inducible activity to purine nucleotides depends on the membranous ubiquinone redox state

“…So far, it has been shown that the Q redox state modulates the PN inhibition of FFAactivated UCPs in the isolated mitochondria of skeletal muscle (UCP3 and UCP2), potato tuber (plant UCP), and A. castellanii (AcUCP) respiring under phosphorylating conditions (Jarmuszkiewicz et al 2004bNavet et al 2005). Moreover, a Q redox state-dependent inhibition of FFA-induced UCPs by PNs has also been observed in the isolated non-phosphorylating mitochondria of A. castellanii (AcUCP) and rat brown adipose tissue (UCP1) (Swida et al 2008;Swida-Barteczka et al 2009). In the present study, we demonstrated that conditions of high ubiquinone (oxidized Q) concentrations facilitated the inhibition of HNE-induced AcUCP-mediated uncoupling by PNs.…”

“…The redox state of Q in steady-state respiration was determined by an extraction technique followed by HPLC detection as previously described (Swida et al 2008). Commercial Q9 (Sigma) was used for peak calibration.…”

“…Linoleic acid is the best known stimulator of AcUCP (Swida et al 2007) and the sensitivity of the LA-induced AcUCPcatalyzed proton leak to PNs is an elegant example of the posttranslational regulation of UCPs, including those of the mitochondria of unicellular organisms (Swida et al 2008;Woyda-Ploszczyca and Jarmuszkiewicz 2011). Therefore, we compared the effect of both HNE (100 μM) and LA (9 μM) on AcUCP activity.…”

“…Moreover, we have shown that UCPs of the mitochondria of unicellular organisms, such as of the amoeba A. castellanii, may play a role in decreasing reactive oxygen species (ROS) production, resulting in the constant level observed throughout the growth cycle of this organism Czarna et al 2007). Recently, PNs have been observed to inhibit FFA-activated AcUCP in phosphorylating and nonphosphorylating mitochondria of A. castellanii in a manner dependent upon the redox state of membranous ubiquinone (coenzyme Q, Q) Swida et al 2008). Therefore, we have proposed that the Q redox state could be a universal metabolic sensor that modulates the PN inhibition of FFA-activated UCPs (Jarmuszkiewicz et al 2010) as is the case in the mitochondria of skeletal muscle (UCP3 and UCP2), potato tuber (plant UCP), and rat brown adipose tissue (UCP1) (Jarmuszkiewicz et al 2004b;Navet et al 2005;Swida-Barteczka et al 2009).…”

Hydroxynonenal-stimulated activity of the uncoupling protein in Acanthamoeba castellanii mitochondria under phosphorylating conditions

“…In A. castellanii mitochondria, the action of AcUCP has been shown to mediate the free fatty acid-and HNE-activated PN-inhibited proton leak, resulting in mitochondrial uncoupling (Jarmuszkiewicz et al , 1999 ;Woyda -Ploszczyca and Jarmuszkiewicz, 2012 ). In the phosphorylating and nonphosphorylating mitochondria of A. castellanii , PNs have been observed to inhibit the free fatty acid-induced AcUCP activity in a manner dependent upon the redox state of membranous ubiquinone (coenzyme Q, Q) Swida et al , 2008 ). Recently, the regulation of Q redox state-dependent PN inhibition has also been described for the HNE-induced AcUCP activity in nonphosphorylating A. castellanii mitochondria (Woyda -Ploszczyca and Jarmuszkiewicz, 2012 ).…”