Adaptation mitochondrial

Adapted from Hatefi, Y, 1985. The mitochondrial electron tran.sport chain and oxidative pho.sphorylation. sy.stem. Annual Review of Biochemistry 54 1015-1069 and DePierre, J., and Ern.ster, L., 1977. Enzyme topology of intracellular membrane.s. Annual Review of Biochemistry 46 201-262. 

Adapted from Harding AE Neurological disease and mitochondrial genes.Trends Neurol Sci 1991 14 132. 

Lopez MF et al. High-throughput profiling of the mitochondrial proteome using affinity fractionation and automation. Electrophoresis 2000 21 3427-3440. Reinheckel T et al. Adaptation of protein carbonyl detection to the requirements of proteome analysis demonstrated for hypoxia/reoxygenation in isolated rat liver mitochondria. Arch Biochem Biophys 2000 376 59-65. 

FIGURE 23.1 Mitochondrial respiratory chain. (Adapted from JF Turrens, BA Freeman, JG Levitt, ID Crapo. Arch Biochem Biophys 217 401-410, 1982.)... 

FIGURE 31-7 Mitochondrial carriers. Ions and small molecules enter the intermembrane space, since the outer mitochondrial membrane is not a significant permeability barrier. However, the inner mitochondrial membrane is impermeable to ions except those for which there are specific carriers. Most of the carriers are reversible, as indicated by two-headed arrows. Compounds transported in one direction are indicated in red. The ATP/ADP translocase and the aspartate-glutamate carrier are both electrophoretic their transport is driven in the direction of the mitochondrial membrane potential, as indicated by red arrows. Glutamine is carried into the matrix by an electroneutral carrier. The unimpaired functioning of mitochondrial carriers is essential for normal metabolism. (Adapted with permission from reference [70].)... 

Anderson, R. M., Barger, J. L., Edwards, M. G., Braun, K. H., O Conner, C. E., Prolla, T. A., and Weindruch, R. (2008). Dynamic regulation of PGC-lalpha localization and turnover implicates mitochondrial adaptation in caloric restriction and the stress response. Aging Cell 7,101-111. 

For example, mitochondrial reductive capacity is decreased with decreased cell numbers but is increased with cells that are activated, such as lymphocytic immune activation, or if cells adapt to the stress associated with toxicity, such as during mitochondrial biogenesis. Thus, mitochondrial reductive capacity might be either increased or decreased with toxicity. Similar contradictory interpretations might occur with other cellular activities, for which there is a compensatory adaptive increase before their failure. This biphasic change is referred to as hormesis and occurs not only with reductive mitochondrial activity but also with mitochondrial number, cell number, mitochondrial membrane potential, antioxidant system activity and numerous other activities. 

FIGURE 11. Left simplified schematic diagram of a mitochondrial ATP-synthase. Adapted from Reference 97 with permission from AAAS. Right binding change mechanism for the synthesis of ATP... 

Vetter RD, Powell MA, Somero GN (1991) Metazoan adaptations to sulfide. In Bryant C (ed) Metazoan Life Without Oxygen. Chapman and Hall, London, pp 109-128 Williams BA, Hirt RP, Lucocq JM, Embley TM (2002) A mitochondrial remnant in the microsporidian Trachipleistophora hominis. Nature 418 865-869 Wolfe AJ (2005) The acetate switch. Microbiol Mol Biol Rev 69 12-50 YarlettN (1994) Fermentation product formation. In Mountfort DO, Orpin CG (eds) Anaerobic Fungi Biology, Ecology and Function. Marcel Dekker, New York, pp 129— 146... 

Chemical analyses of membranes isolated from various sources reveal certain common properties. Each kingdom, each species, each tissue or cell type, and the organelles of each cell type have a characteristic set of membrane lipids. Plasma membranes, for example, are enriched in cholesterol and contain no detectable cardiolipin (Fig. 11-2) in the inner mitochondrial membrane of the hepatocyte, this distribution is reversed very low cholesterol and high cardiolipin. Cardiolipin is essential to the function of certain proteins of the inner mitochondrial membrane. Cells clearly have mechanisms to control the kinds and amounts of membrane lipids they synthesize and to target specific lipids to particular organelles. In many cases, we can surmise the adaptive advantages of distinct combinations of membrane lipids in other cases, the functional significance of these combinations is as yet unknown. 

The combined activity of the rubisco oxygenase and the glycolate salvage pathway consumes 02 and produces C02—hence the name photorespiration. This pathway is perhaps better called the oxidative photosynthetic carbon cycle or C2 cycle, names that do not invite comparison with respiration in mitochondria. Unlike mitochondrial respiration, photorespiration does not conserve energy and may actually inhibit net biomass formation as much as 50%. This inefficiency has led to evolutionary adaptations in the carbon-assimilation processes, particularly in plants that have evolved in warm climates. 

Poole1305 has reviewed the bacterial cytochrome oxidases, and has drawn attention to features which are not present in the mitochondrial enzyme, and which reflect the metabolic diversity and adaptability of bacteria. These are (1) the synthesis of the oxidases is controlled dramatically by the prevailing environmental conditions (2) some oxidases are multifunctional, and may use electron acceptors other than dioxygen (3) more than one type of oxidase may be present, each terminating a branched electron-transfer pathway. 

The results of studies using a wide range of oxidizable substrates showed that, in fact, there was a modicum of temperature compensation, but that it was nothing like the metabolic cold adaptation originally envisaged. Some thermal compensation was also achieved by increasing the density of cristae within the mitochondria, but this was of less importance than actual mitochondrial density. 

Wodtke, E. (1978). Lipid adaptation in liver mitochondrial membranes of carp acclimated to different environmental temperatures. Phospholipid composition, fatty acid pattern and cholesterol content. Biochimica etBiophysicaActa 529,280-291. 

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