Protein Family Models

This family consists of several Cbb3-type cytochrome oxidase components (FixQ/CcoQ). FixQ is found in nitrogen fixing bacteria. Since nitrogen fixation is an energy-consuming process, effective symbioses depend on operation of a respiratory chain with a high affinity for O2, closely coupled to ATP production. This requirement is fulfilled by a special three-subunit terminal oxidase (cytochrome terminal oxidase cbb3), which was first identified in Bradyrhizobium japonicum as the product of the fixNOQP operon [1]. [1]. 11717256. Regulation of gene expression in response to oxygen in Rhizobium etli: role of FnrN in fixNOQP expression and in symbiotic nitrogen fixation. Lopez O, Morera C, Miranda-Rios J, Girard L, Romero D, Soberon M;. J Bacteriol 2001;183:6999-7006. (from Pfam)

Date:

2024-10-16

Members of this protein family are restricted to the epsilon branch of the Proteobacteria. All members are found in operons containing the other three structural subunits of the cbb3 type of cytochrome c oxidase. These small proteins show remote sequence similarity to the CcoQ subunit in other cytochrome c oxidase systems, so this family is assumed to represent the epsilonproteobacterial variant of CcoQ.

Date:

2021-05-12