8.A.79 The 3 TMS cyd Operon Protein, CydX (CydX) Family
cydX (ybgE) is a gene within the cyd operon of E. coli. The encoded protein has 97 aas and 3 TMSs and is essential for CydAB function (VanOrsdel et al. 2013). Homologues in other organisms have the same or a similar topology. It is requried for the assembly and stability of the diheme active site (Hoeser et al. 2014). It may play a role in a functional interaction with the CydA Q-loop, an enigmatic domain of the cytochrome bd oxidase complex (Allen et al. 2014).