Modeling the Effects of Microgravity on Oxidation in Mitochondria: A Protein Damage Assessment across a Diverse Set of Life Forms

Exposure to microgravity conditions is detrimental to animal and human protein tissue and is linked to ailments associated with aging, disease and other disorders originating at the protein level. With exposure, dangerously low blood pressure results from diminished blood production forces the heart to beat at abnormal rates and causes damage. The heart, like the other muscles of the body, risk developing muscular atrophy from the reduced dependence on muscle-use. Oxidative carbonylation, the addition of a CO to an amino acid chain, is a natural process used by the cell to degrade and remove proteins. This reaction may also cause many of the diseases associated with protein dysfunction (Alzheimer's, muscular atrophy, Parkinsons, sepsis, etc.). Although aging has been associated with similar ailments from protein degradation, the stress from weightlessness is thought to increase the rates of oxidative processes impacting general health by upsetting protein function and its structure. Carbonylation is an oxidative reaction for which, motifs high in R, K, P, T, E and S residues can be used to explore its composition in protein data. Since mitochondria also apply oxidative processes to make energy, we hypothesize that this reaction is highly contained so as to minimize local oxidative damage. In this paper, we evaluate the coverage of motifs which are likely attractors of oxidative activity across mitochondrial and non-mitochondrial protein data of fourteen diverse organisms. Here we show that mitochondrial proteins have generally reduced amounts of the same oxidative carbonylation content which we found in abundance in the organism's nuclear proteins. Furthermore, we show that this general finding is similar between two major profiling systems: oxidative carbonylation (RKPT enriched sequences) and protein degradation (PEST sequences). We suggest an mitochondrial intolerance for motifs that may attract forms of oxidation.