Article

The peroxiredoxin repair proteins.

Center for Structural Biology, Department of Biochemistry, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA.
Sub-cellular biochemistry 02/2007; 44:115-41. DOI: 10.1007/978-1-4020-6051-9_6
Source: PubMed

ABSTRACT Sulfiredoxin and sestrin are cysteine sulfinic acid reductases that selectively reduce or repair the hyperoxidized forms of typical 2-Cys peroxiredoxins within eukaryotes. As such these enzymes play key roles in the modulation of peroxide-mediated cell signaling and cellular defense mechanisms. The unique structure of sulfiredoxin facilitates access to the peroxiredoxin active site and novel sulfur chemistry.

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    ABSTRACT: Mitochondrial respiration provides the energy needed to drive metabolic and transport processes in cells. Mitochondria are a significant site of reactive oxygen species (ROS) production in plant cells, and redox-system components obey fine regulation mechanisms that are essential in protecting the mitochondrial integrity. In addition to ROS, there are compelling indications that nitric oxide (NO.) can be generated in this organelle by both reductive and oxidative pathways. ROS and reactive nitrogen species (RNS) play a key role in signaling but they can also be deleterious via oxidation of macromolecules. The high production of ROS obligates mitochondria to be provided with a set of ROS scavenging mechanisms. The first line of mitochondrial antioxidants is composed of superoxide dismutase and the enzymes of the ascorbate-glutathione cycle, which are not only able to scavenge ROS but also to repair cell damage and possibly serve as redox sensors. The dithiol-disulfide exchanges form independent signaling nodes and act as antioxidant defense mechanisms as well as sensor proteins modulating redox signaling during development and stress adaptation. The presence of thioredoxin (Trx), peroxiredoxin (Prx) and sulfiredoxin (Srx) in the mitochondria has been recently reported. Cumulative results obtained from studies in salt stress models have demonstrated that these redox proteins play a significant role in the establishment of salt tolerance. The Trx/Prx/Srx system may be subjected to a fine regulated mechanism involving post-translational modifications, among which S-glutathionylation and S-nitrosylation seem to exhibit a critical role that is just beginning to be understood. This review summarizes our current knowledge in antioxidative systems in plant mitochondria, their interrelationships, mechanisms of compensation and some unresolved questions, with special focus on their response to abiotic stress.
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