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Biogenesis of cbb₃-type cytochrome c oxidase in Rhodobacter capsulatus

Ekici, Seda, Pawlik, Grzegorz, Lohmeyer, Eva, Koch, Hans-Georg, Daldal, Fevzi
Biochimica et biophysica acta 2012 v.1817 no.6 pp. 898-910
Rhodobacter capsulatus, bacteria, biogenesis, cytochrome c, cytochrome-c oxidase, heme, membrane proteins, models, nitric oxide, nitrogen fixation, oxygen, photosynthesis, phylogeny, tissues
The cbb₃-type cytochrome c oxidases (cbb₃-Cox) constitute the second most abundant cytochrome c oxidase (Cox) group after the mitochondrial-like aa₃-type Cox. They are present in bacteria only, and are considered to represent a primordial innovation in the domain of Eubacteria due to their phylogenetic distribution and their similarity to nitric oxide (NO) reductases. They are crucial for the onset of many anaerobic biological processes, such as anoxygenic photosynthesis or nitrogen fixation. In addition, they are prevalent in many pathogenic bacteria, and important for colonizing low oxygen tissues. Studies related to cbb₃-Cox provide a fascinating paradigm for the biogenesis of sophisticated oligomeric membrane proteins. Complex subunit maturation and assembly machineries, producing the c-type cytochromes and the binuclear heme b₃-CuB center, have to be coordinated precisely both temporally and spatially to yield a functional cbb₃-Cox enzyme. In this review we summarize our current knowledge on the structure, regulation and assembly of cbb₃-Cox, and provide a highly tentative model for cbb₃-Cox assembly and formation of its heme b₃-CuB binuclear center. This article is part of a Special Issue entitled: Biogenesis/Assembly of Respiratory Enzyme Complexes.