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.
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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