Sandbox Reserved 1625: Difference between revisions

Cytochrome ''bd'' oxidase is made up of four individual subunits.<ref name="Alexander">PMID:31723136</ref> The two major subunits, CydA and CydB, are each composed of one peripheral helix and two bundles of four transmembrane helices. The <scene name='83/832924/Cyda_subunit/6'>CydA subunit</scene> plays the most important role in the oxygen reduction reaction as it contains the Q-loop as well as all three [https://en.wikipedia.org/wiki/Heme heme] groups. The <scene name='83/832924/Cydb_subunit/2'>CydB subunit</scene> harbors the <scene name='83/832924/Ubiquinone/3'>ubiquinone</scene> molecule which provides structural support to the subunit that mimics the three hemes found in CydA.<ref name="Safarian">PMID: 31604309</ref><ref name="Safarian2">PMID: 27126043</ref> The remaining two subunits, CydS and CydX, are both single helix structures that assist in the oxygen reduction reaction. Unique to ''E. coli'', the <scene name='83/832924/Cyds_subunit/4'>CydS subunit</scene> binds to CydA to block oxygen from directly binding to heme b₅₉₅. The <scene name='83/832924/Cydx_subunit/4'>CydX subunit</scene> promotes the assembly and stability of the oxidase complex. CydX is composed of 37 mostly hydrophilic amino acid residues, including <scene name='83/832924/Glu25/2'>Glu25</scene> that is exposed to the cytoplasm and prevents the helix from fully entering the membrane. <ref name="Alexander">PMID:31723136</ref>