Abstract
Cytochrome c (cyt c) family proteins, such as horse cyt c, Pseudomonas aeruginosa cytochrome c 551 (PA cyt c 551), and Hydrogenobacter thermophilus cytochrome c 552 (HT cyt c 552), have been used as model proteins to study the relationship between the protein structure and folding process. We have shown in the past that horse cyt c forms oligomers by domain swapping its C-terminal helix, perturbing the Met–heme coordination significantly compared to the monomer. HT cyt c 552 forms dimers by domain swapping the region containing the N-terminal α-helix and heme, where the heme axial His and Met ligands belong to different protomers. Herein, we show that PA cyt c 551 also forms domain-swapped dimers by swapping the region containing the N-terminal α-helix and heme. The secondary structures of the M61A mutant of PA cyt c 551 were perturbed slightly and its oligomer formation ability decreased compared to that of the wild-type protein, showing that the stability of the protein secondary structures is important for domain swapping. The hinge loop of domain swapping for cyt c family proteins corresponded to the unstable region specified by hydrogen exchange NMR measurements for the monomer, although the swapping region differed among proteins. These results show that the unstable loop region has a tendency to become a hinge loop in domain-swapped proteins.
Highlights
In domain swapping, a protein molecule exchanges its secondary or tertiary structural unit with the corresponding unit of another molecule of the same protein [1,2]
Met–heme coordination contributes to the stability of the structure and the ability of electron transfer in cyt c family proteins [48,53,54,55]
The optical absorption spectra and redox potentials were similar between monomeric and dimeric WT PA cyt c551, heme-ligating His and Met originated from different protomers in the dimer (Fig 3), similar to the case of dimeric HT cyt c552 [18]
Summary
A protein molecule exchanges its secondary or tertiary structural unit with the corresponding unit of another molecule of the same protein [1,2]. 5% of protein families based on protein structural classification [3] have been found to contain domain-swapped structures [4]. Domain swapping has been reported in human pathology-. Domain-Swapped Dimer of Pseudomonas aeruginosa Cytochrome c551
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
