دانلود رایگان مقاله سیستم انتقال الکترون متصل به غشا از یک باکتری آناموکس

ABSTRACT

Electron transport, or oxidative phosphorylation, is one of the hallmarks of life. To this end, prokaryotes evolved a vast variety of protein complexes, only a small part of which have been discovered and studied. These protein complexes allow them to occupy virtually every ecological niche on Earth. Here, we applied the method of proteomics-based complexome profiling to get a better understanding of the electron transport systems of the anaerobic ammonium-oxidizing (anammox) bacteria, the N2-producing key players of the global nitrogen cycle. By this method nearly all respiratory complexes that were previously predicted from genome analysis to be involved in energy and cell carbon fixation were validated. More importantly, new and unexpected ones were discovered. We believe that complexome profiling in concert with (meta)genomics offers great opportunities to expand our knowledge on bacterial respiratory processes at a rapid and massive pace, in particular in new and thus far poorly investigated non-model and environmentally-relevant species.

4. Discussion

Complexome profiling presented a very suitable tool for the comprehensive analysis of respiratory protein complexes in K. stuttgartiensis. This method verified the presence of not only nearly all RCs but also other protein complexes that had been predicted from genomic analyses [26] and results, such as the composition of the HZS [27] and NXR proteins [39,40], were in full agreement with still scarce experimental evidence. The method showed how gene products of long gene clusters assembled as distinct protein complexes that are known from other organisms (complex I, ATP synthase) or that are typical for anammox bacteria, such as the hzs and nxr systems for which the assembly of the hypothetical ETM and NXRmemb complex, respectively, could be shown (Fig. 2 and Fig. 3; Supporting information, Fig. 4). The method even allowed the detection of an RC, NAD+:ferredoxin oxidoreductase (RNF), composed of subunits encoded by genes that are spread over the genome. On top of this, results obtained by complexome profiling changed ou