Evolution of cytochrome oxidase, an enzyme older than atmospheric oxygen.

摘要: Cytochrome oxidase is a key enzyme in aerobic metabolism. All the recorded eubacterial (domain Bacteria) and archaebacterial (Archaea) sequences of subunits 1 2 this protein complex have been used for comprehensive evolutionary analysis. The phylogenetic trees reveal several processes gene duplication. Some these are ancient, having occurred common ancestor Bacteria Archaea, whereas others specific lines Bacteria. We show that quinol was derived from cytochrome c Gram-positive bacteria has an independent origin. A considerable amount evidence suggests Proteobacteria (Purple bacteria) acquired through lateral transfer bacteria. prevalent hypothesis metabolism arose times evolution after oxygenic photosynthesis, not sustained by two aspects molecular data. First, present Archaea photosynthesis appeared Second, extant nitrogen-fixing shows possible environment with very low level oxygen, such as root nodules leguminous plants. Therefore, we propose organisms monophyletic ancient origin, prior to appearance photosynthetic organisms.