Oxidised protein metabolism: recent insights

Abstract

Abstract:The 'oxygen paradox' arises from the fact that oxygen, the molecule that aerobic life depends on, threatens its very existence. An oxygen-rich environment provided life on Earth with more efficient bioenergetics and, with it, the challenge of having to deal with a host of oxygen-derived reactive species capable of damaging proteins and other crucial cellular components. In this minireview, we explore recent insights into the metabolism of proteins that have been reversibly or irreversibly damaged by oxygen-derived species. We discuss recent data on the important roles played by the proteasomal and lysosomal systems in the proteolytic degradation of oxidatively damaged proteins and the effects of oxidative damage on the function of the proteolytic pathways themselves. Mitochondria are central to oxygen utilisation in the cell, and their ability to handle oxygen-derived radicals is an important and still emerging area of research. Current knowledge of the proteolytic machinery in the mitochondria, including the ATPdependent AAA+ proteases and mitochondrial-derived vesicles, is also highlighted in the review. Significant progress is still being made in regard to understanding the mechanisms underlying the detection and degradation of oxidised proteins and how proteolytic pathways interact with each other. Finally, we highlight a few unanswered questions such as the possibility of oxidised amino acids released from oxidised proteins by proteolysis being re-utilised in protein synthesis thus establishing a vicious cycle of oxidation in cells.

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“…Mitochondria are eukaryotic organelle and mainly involved in many metabolic processes, including metabolism of glucose, fat, protein, and nucleic acid (27)(28)(29)(30). Mitochondrial dysfunction is a key reason in many pathogenic processes, including metabolism, cell death, autophagy, and viral infection (31,32).…”

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“…The proteins can also undergo oxidation [40]: The targets are both amino acid residues (Fig. 3b) and cofactors.…”

“…Other important thiols are those found in exofacial proteins located at the extracellular surface of cells, which may act as sensors of the redox state [156]. Yet in connection with the redox balance, protein thiols are known to be very sensitive to ROS [40]. Lastly, H2S is a potential gaseous transmitter in biological systems, which can be produced in vivo from cysteine, homocysteine and cystathionine.…”

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“…The maintenance of cell redox state is important to cell viability [43]. The increased level of reactive species can lead to oxidative damage to a vast number of biological molecules, as DNA [44][45][46], proteins [47], lipids [48], including membranes [3] leading to a range of pathologies, as cancer [36], neurological disease [49], cardiac disease [50,51], inflammation process [52] and aging.…”