6F6B image
Entry Detail
PDB ID:
6F6B
Keywords:
Title:
R2-like ligand-binding oxidase A171F mutant with anaerobically reconstituted Mn/Fe cofactor
Biological Source:
PDB Version:
Deposition Date:
2017-12-05
Release Date:
2018-12-19
Method Details:
Experimental Method:
Resolution:
2.01 Å
R-Value Free:
0.22
R-Value Work:
0.18
R-Value Observed:
0.18
Space Group:
I 2 2 2
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Ribonucleotide reductase small subunit
Mutations:A171F
Chain IDs:A
Chain Length:316
Number of Molecules:1
Biological Source:Geobacillus kaustophilus (strain HTA426)
Primary Citation
Assembly of a heterodinuclear Mn/Fe cofactor is coupled to tyrosine-valine ether cross-link formation in the R2-like ligand-binding oxidase.
J. Biol. Inorg. Chem. 24 211 221 (2019)
PMID: 30689052 DOI: 10.1007/s00775-019-01639-4

Abstact

R2-like ligand-binding oxidases (R2lox) assemble a heterodinuclear Mn/Fe cofactor which performs reductive dioxygen (O2) activation, catalyzes formation of a tyrosine-valine ether cross-link in the protein scaffold, and binds a fatty acid in a putative substrate channel. We have previously shown that the N-terminal metal binding site 1 is unspecific for manganese or iron in the absence of O2, but prefers manganese in the presence of O2, whereas the C-terminal site 2 is specific for iron. Here, we analyze the effects of amino acid exchanges in the cofactor environment on cofactor assembly and metalation specificity using X-ray crystallography, X-ray absorption spectroscopy, and metal quantification. We find that exchange of either the cross-linking tyrosine or the valine, regardless of whether the mutation still allows cross-link formation or not, results in unspecific manganese or iron binding at site 1 both in the absence or presence of O2, while site 2 still prefers iron as in the wild-type. In contrast, a mutation that blocks binding of the fatty acid does not affect the metal specificity of either site under anoxic or aerobic conditions, and cross-link formation is still observed. All variants assemble a dinuclear trivalent metal cofactor in the aerobic resting state, independently of cross-link formation. These findings imply that the cross-link residues are required to achieve the preference for manganese in site 1 in the presence of O2. The metalation specificity, therefore, appears to be established during the redox reactions leading to cross-link formation.

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