Summary for 8C7P
| Entry DOI | 10.2210/pdb8c7p/pdb |
| Related | 6ffv |
| Descriptor | Cobalamin ABC transporter, COBALAMIN (2 entities in total) |
| Functional Keywords | cobalamin, membrane transporter, transport protein |
| Biological source | Thiobacillus denitrificans ATCC 25259 |
| Total number of polymer chains | 1 |
| Total formula weight | 23125.07 |
| Authors | Martinez-Felices, J.M.,Slotboom, D.J. (deposition date: 2023-01-16, release date: 2024-01-31, Last modification date: 2024-08-21) |
| Primary citation | Martinez Felices, J.M.,Barreto, Y.B.,Thangaratnarajah, C.,Whittaker, J.J.,Alencar, A.M.,Guskov, A.,Slotboom, D.J. Cobalamin decyanation by the membrane transporter BtuM. Structure, 32:1165-1173.e3, 2024 Cited by PubMed Abstract: BtuM is a bacterial cobalamin transporter that binds the transported substrate in the base-off state, with a cysteine residue providing the α-axial coordination of the central cobalt ion via a sulfur-cobalt bond. Binding leads to decyanation of cobalamin variants with a cyano group as the β-axial ligand. Here, we report the crystal structures of untagged BtuM bound to two variants of cobalamin, hydroxycobalamin and cyanocobalamin, and unveil the native residue responsible for the β-axial coordination, His28. This coordination had previously been obscured by non-native histidines of His-tagged BtuM. A model in which BtuM initially binds cobinamide reversibly with low affinity (K = 4.0 μM), followed by the formation of a covalent bond (rate constant of 0.163 s), fits the kinetics data of substrate binding and decyanation of the cobalamin precursor cobinamide by BtuM. The covalent binding mode suggests a mechanism not used by any other transport protein. PubMed: 38733996DOI: 10.1016/j.str.2024.04.014 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (3 Å) |
Structure validation
Download full validation report
