The effects of hydrogen peroxide on the translational activity in mitochondria -- Konstantinov, YM, Subota, IY, Arziev, AS, Katyshev, AI Recent findings suggest that at moderately high concentrations certain forms of reactive oxygen species (ROS) such as H2O2 may act as signal transduction messengers (Sen and Packer, FASEB J 10:709-720, 1996) and/or participate in redox regulation of gene expression, particularly by means of redox regulation of appropriate transcription activators (Sun and Oberley, Free Radic Biol Med 21:335-348, 1996). We showed that chemical and physiological redox agents influence significantly transcriptional and translational activities in isolated mitochondria (MNL 72:33, 1998). Substantial activation of both transcription and translation in mitochondria under oxidizing conditions and its strong repression under reducing conditions suggest potential multi-level redox control of mitochondrial gene expression. These data showed also that the translational activity of mitochondria is subjected to the presumably regulatory influence of the redox state of glutathione. Little is known about the effects of hydrogen peroxide as a potential regulatory molecule on the activity of protein synthesis in mitochondria.

In this work we investigated the influence of hydrogen peroxide on the translational activity of mitochondria to compare effects of this physiological oxidant with other redox agents. Mitochondria were isolated from 3-day-old etiolated maize seedlings (hybrid VIR42 MV) by a standard method of differential centrifugation. Mitochondrial protein was determined by the Lowry method. Protein synthesis in mitochondria was measured according to the method of Bhat et al. (Biochemistry 21:2452-2460, 1982) with the use of [35S]-methionine.

Figure.

The results obtained show that hydrogen peroxide (0.5 mM and 1 mM) caused the significant increase of translational activity in maize mitochondria (Figure 1). There were no substantial differences between activation effect of the oxidized form of glutathione (GSSG) and hydrogen peroxide. These data suggest that a physiological oxidant such as hydrogen peroxide may be one of the regulatory factors involved in multi-level redox control of mitochondrial gene expression.
 
 


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