6QK5
Solution Structure of the Zn-loaded form of a Metallothionein from Helix Pomatia
Summary for 6QK5
| Entry DOI | 10.2210/pdb6qk5/pdb |
| NMR Information | BMRB: 34355 |
| Descriptor | Cadmium-metallothionein, ZINC ION (2 entities in total) |
| Functional Keywords | metallothionein, cadmium protein, snail protein, helix pomatia, metal binding protein |
| Biological source | Helix pomatia (Roman snail) |
| Total number of polymer chains | 1 |
| Total formula weight | 7028.09 |
| Authors | |
| Primary citation | Beil, A.,Jurt, S.,Walser, R.,Schonhut, T.,Guntert, P.,Palacios, O.,Atrian, S.,Capdevila, M.,Dallinger, R.,Zerbe, O. The Solution Structure and Dynamics of Cd-Metallothionein fromHelix pomatiaReveal Optimization for Binding Cd over Zn. Biochemistry, 58:4570-4581, 2019 Cited by PubMed Abstract: Metallothioneins (MTs) are cysteine-rich polypeptides that are naturally found coordinated to monovalent and/or divalent transition metal ions. Three metallothionein isoforms from the Roman snail are known. They differ in their physiological metal load and in their specificity for transition metal ions such as Cd (HpCdMT isoform) and Cu (HpCuMT isoform) or in the absence of a defined metal specificity (HpCd/CuMT isoform). We have determined the solution structure of the Cd-specific isoform (HpCdMT) by nuclear magnetic resonance spectroscopy using recombinant isotopically labeled protein loaded with Zn or Cd. Both structures display two-domain architectures, where each domain comprises a characteristic three-metal cluster similar to that observed in the β-domains of vertebrate MTs. The polypeptide backbone is well-structured over the entire sequence, including the interdomain linker. Interestingly, the two domains display mutual contacts, as observed before for the metallothionein of the snail , to which both N- and C-terminal domains are highly similar. Increasing the length of the linker motionally decouples both domains and removes mutual contacts between them without having a strong effect on the stability of the individual domains. The structures of Cd- and Zn-HpCdMT are nearly identical. However, N relaxation, in particular N rates, is accelerated for many residues of Zn-HpCdMT but not for Cd-HpCdMT, revealing the presence of conformational exchange effects. We suggest that this snail MT isoform is evolutionarily optimized for binding Cd rather than Zn. PubMed: 31633358DOI: 10.1021/acs.biochem.9b00830 PDB entries with the same primary citation |
| Experimental method | SOLUTION NMR |
Structure validation
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