Domain-swapped cytochrome cb₅₆₂dimer and its nanocage encapsulating a Zn–SO₄cluster in the internal cavity

Abstract

Three domain-swapped cytochrome cb 562 dimers formed a unique cage structure with a Zn–SO4 cluster inside the cavity.

Formation and carbon monoxide‐dependent dissociation of Allochromatium vinosum cytochrome c′ oligomers using domain‐swapped dimers

“…Domain swapping oligomerizations of four helix bundle proteins have also been reported for WA20 and cyt cb 562 . The domain‐swapped dimer of WA20 exhibited a long four helix bundle structure with loop‐to‐helix transitions at the short loops between helices αA and αB and between helices αC and αD upon dimerization.…”

“…AVCP is the first example of the domain swapping oligomerization of a class II cyt c . Oligomers formed by domain swapping are frequently metastable and dissociate to monomers irreversibly . In these proteins, the stability of domain‐swapped oligomers correlates well to that of its monomer, since most of the interactions in the monomer are reproduced in the domain‐swapped oligomer, although some of the interactions may convert from within a molecule to between protomers.…”

“…The domain‐swapped dimer of WA20 exhibited a long four helix bundle structure with loop‐to‐helix transitions at the short loops between helices αA and αB and between helices αC and αD upon dimerization. However, AVCP and cyt cb 562 possess long loops between helices αB and αC, and a part of the long loop becomes the hinge loop in domain‐swapping . As a result, dimeric WA20 forms a rod structure, whereas domain‐swapped dimeric cyt cb 562 and AVCP form dogleg structures, demonstrating that the length of the loop containing the hinge region may affect the domain‐swapped dimer structures in four helix bundle proteins.…”

“…Class I monomeric globular c ‐type cytochromes [e.g., horse cytochrome (cyt) c , mesophile Pseudomonas aeruginosa (PA) cyt c 551 , thermophile Hydrogenobacter thermophilus (HT) cyt c 552 , and hyperthermophile Aquifex aeolicus (AA) cyt c 555 ] form domain‐swapped oligomers by exchanging the N‐ or C‐terminal region between molecules . The c ‐type mutant of Escherichia coli cyt b 562 (cyt cb 562 ) exhibiting a four helix bundle structure, as well as horse myoglobin (Mb) possessing a noncovalently bound heme, form domain‐swapped dimers by exchanging half of the structure between molecules . Domain swapping has also been used to construct various protein oligomers.…”

“…[31][32][33][34] The c-type mutant of Escherichia coli cyt b 562 (cyt cb 562 ) exhibiting a four helix bundle structure, as well as horse myoglobin (Mb) possessing a noncovalently bound heme, form domain-swapped dimers by exchanging half of the structure between molecules. 35,36 Domain swapping has also been used to construct various protein oligomers. We have constructed an artificial Mb heterodimer, which possessed two different heme coordination sites: His/H 2 O and bis-His coordinated hemes.…”