Download MendeleyRational design of metal-binding sites in domain-swapped myoglobin dimers.
Nagao, S., Idomoto, A., Shibata, N., Higuchi, Y., Hirota, S.(2021) J Inorg Biochem 217: 111374-111374
- PubMed: 33578251
- DOI: https://doi.org/10.1016/j.jinorgbio.2021.111374
- Primary Citation of Related Structures:
7DGJ, 7DGK, 7DGL, 7DGM, 7DGN, 7DGO - PubMed Abstract:
The metal active site is precisely designed in metalloproteins. Here we applied 3D domain swapping, a phenomenon in which a partial protein structure is exchanged between molecules, to introduce metal sites in proteins. We designed multiple metal-binding sites specific to domain-swapped myoglobin (Mb) with His mutation. Stable dimeric Mbs with metal-binding sites were obtained by shifting the His position and introducing two Ala residues in the hinge region (K78H/G80A/H82A and K79H/G80A/H81A Mbs). The absorption and circular dichroism spectra of the monomer and dimer of K78H/G80A/H82A and K79H/G80A/H81A Mbs were similar to the corresponding spectra, respectively, of wild-type Mb. No negative peak due to dimer-to-monomer dissociation was observed below the denaturation temperature in the differential scanning calorimetry thermograms of K78H/G80A/H82A and K79H/G80A/H81A Mbs, whereas the dimer dissociates into monomers at 68 °C for wild-type Mb. These results show that the two mutants were stable in the dimer state. Metal ions bound to the metal-binding sites containing the introduced His in the domain-swapped Mb dimers. Co 2+ -bound and Ni 2+ -bound K78H/G80A/H82A Mb exhibited octahedral metal-coordination structures, where His78, His81, Glu85, and three H 2 O/OH - molecules coordinated to the metal ion. On the other hand, Co 2+ -bound and Zn 2+ -bound K79H/G80A/H81A Mb exhibited tetrahedral metal-coordination structures, where His79, His82, Asp141, and a H 2 O/OH - molecule coordinated to the metal ion. The Co 2+ -bound site exists deep inside the protein in the K79H/G80A/H81A Mb dimer, which may allow the unique tetrahedral coordination for the Co 2+ ion. These results show that we can utilize domain swapping to construct artificial metalloproteins.
Organizational Affiliation:
Division of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan. Electronic address: s-nagao@sci.u-hyogo.ac.jp.
