7S9Z

Helicobacter Hepaticus CcsBA Closed Conformation

Summary for 7S9Z

• Entry DOI: 10.2210/pdb7s9z/pdb
• EMDB information: 24942
• Descriptor: Cytochrome c biogenesis protein, PHOSPHATIDYLETHANOLAMINE, HEME B/C (3 entities in total)
• Functional Keywords: cytochrome c biogenesis, heme transporter, heme lyase, membrane protein
• Biological source: Helicobacter hepaticus
• Total number of polymer chains: 1
• Total formula weight: 108644.01

Authors

Mendez, D.L.,Lowder, E.P.,Tillman, D.E.,Sutherland, M.C.,Collier, A.L.,Rau, M.J.,Fitzpatrick, J.A.,Kranz, R.G. (deposition date: 2021-09-21, release date: 2021-12-22, Last modification date: 2024-10-23)

Primary citation

Mendez, D.L.,Lowder, E.P.,Tillman, D.E.,Sutherland, M.C.,Collier, A.L.,Rau, M.J.,Fitzpatrick, J.A.J.,Kranz, R.G.
Cryo-EM of CcsBA reveals the basis for cytochrome c biogenesis and heme transport.
Nat.Chem.Biol., 18:101-108, 2022

PubMed Abstract: Although the individual structures and respiratory functions of cytochromes are well studied, the structural basis for their assembly, including transport of heme for attachment, are unknown. We describe cryo-electron microscopy (cryo-EM) structures of CcsBA, a bifunctional heme transporter and cytochrome c (cyt c) synthase. Models built from the cryo-EM densities show that CcsBA is trapped with heme in two conformations, herein termed the closed and open states. The closed state has heme located solely at a transmembrane (TM) site, with a large periplasmic domain oriented such that access of heme to the cytochrome acceptor is denied. The open conformation contains two heme moieties, one in the TM-heme site and another in an external site (P-heme site). The presence of heme in the periplasmic site at the base of a chamber induces a large conformational shift that exposes the heme for reaction with apocytochrome c (apocyt c). Consistent with these structures, in vivo and in vitro cyt c synthase studies suggest a mechanism for transfer of the periplasmic heme to cytochrome.

PubMed: 34931065
DOI: 10.1038/s41589-021-00935-y

Experimental method

ELECTRON MICROSCOPY (4.14 Å)