Yamanaka M, Hoshizumi M, Nagao S, Nakayama R, Shibata N, Higuchi Y, Hirota S. Formation and carbon monoxide-dependent dissociation of Allochromatium vinosum cytochrome c' oligomers using domain-swapped dimers.
Protein Sci 2017;
26:464-474. [PMID:
27883268 PMCID:
PMC5326568 DOI:
10.1002/pro.3090]
[Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 11/18/2016] [Accepted: 11/18/2016] [Indexed: 12/12/2022]
Abstract
The number of artificial protein supramolecules has been increasing; however, control of protein oligomer formation remains challenging. Cytochrome c' from Allochromatium vinosum (AVCP) is a homodimeric protein in its native form, where its protomer exhibits a four-helix bundle structure containing a covalently bound five-coordinate heme as a gas binding site. AVCP exhibits a unique reversible dimer-monomer transition according to the absence and presence of CO. Herein, domain-swapped dimeric AVCP was constructed and utilized to form a tetramer and high-order oligomers. The X-ray crystal structure of oxidized tetrameric AVCP consisted of two monomer subunits and one domain-swapped dimer subunit, which exchanged the region containing helices αA and αB between protomers. The active site structures of the domain-swapped dimer subunit and monomer subunits in the tetramer were similar to those of the monomer subunits in the native dimer. The subunit-subunit interactions at the interfaces of the domain-swapped dimer and monomer subunits in the tetramer were also similar to the subunit-subunit interaction in the native dimer. Reduced tetrameric AVCP dissociated to a domain-swapped dimer and two monomers upon CO binding. Without monomers, the domain-swapped dimers formed tetramers, hexamers, and higher-order oligomers in the absence of CO, whereas the oligomers dissociated to domain-swapped dimers in the presence of CO, demonstrating that the domain-swapped dimer maintains the CO-induced subunit dissociation behavior of native ACVP. These results suggest that protein oligomer formation may be controlled by utilizing domain swapping for a dimer-monomer transition protein.
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