Science Advances

Supplementary Materials

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  • Fig. S1. Structural characterization of ScoIox, ScoI·Cu2+, CoxB·CuA, and PcuC.
  • Fig. S2. Amino acid sequence alignment of PcuC homologs.
  • Fig. S3. EPR determination of distances between two Cu2+ ions in PcuC·Cu2+·Cu2+.
  • Fig. S4. NMR experiments showing that the C-terminally truncated PcuC variant PcuC ΔC can also bind Cu2+.
  • Fig. S5. Investigation of the Cu2+-binding properties of the C-terminal PcuC peptide by NMR.
  • Fig. S6. Absorbance spectra of ScoI·Cu2+·CoxB, CoxB·CuA, ScoI·Cu2+, and PcuC·Cu1+·Cu2+.
  • Fig. S7. Equilibrium competition between PcuC or ScoI and BCS for binding of Cu1+ reveals a specific high-affinity Cu1+-binding site in the PcuC core domain and a low-affinity Cu1+-binding site in the C-terminal PcuC extension and demonstrates that ScoI does not bind Cu1+.
  • Fig. S8. Detection of cytochrome oxidase activity in B. diazoefficiens mutants under copper starvation.
  • Fig. S9. NMR analysis of Cu transfer from PcuC·Cu1+·Cu2+ to the ScoI·Cu2+·CoxB complex.
  • Fig. S10. Alternative, but disfavored, mechanism of CoxB·CuA formation from CoxB·Cu2+ and only one equivalent of PcuC·Cu1+·Cu2+.
  • Fig. S11. Cw EPR spectra of the PcuC·Cu1+·Cu2+ + ScoI·Cu2+·CoxB reaction mixture.
  • Fig. S12. The ScoI·Cu2+ complex shows limited long-term stability due to Cu2+-induced formation of a disulfide bond between the active-site cysteines of ScoI that causes release of Cu2+.
  • Fig. S13. CoxB·CuA formation from apo-CoxB and PcuC·Cu1+·Cu2+ in the absence of ScoI.
  • Table S1. X-ray data collection and refinement statistics (molecular replacement).

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