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Updated: Jan 16, 2026
11:38
Quantifying the Binding Interactions Between CuII and Peptide Residues in the Presence and Absence of Chromophores
Published on: April 5, 2022
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Two sites, two stories: sequence-driven divergence in Cu(II) and Zn(II) binding to CusF
Michał Pakowski1, Aleksandra Hecel1
1Faculty of Chemistry, University of Wroclaw, 50383 Wroclaw, Poland. aleksandra.hecel2@uwr.edu.pl.
Dalton Transactions (Cambridge, England : 2003)
|October 1, 2025
Summary
Bacterial copper homeostasis relies on CusF. This study shows that histidine spacing in CusF mimics dictates copper selectivity, with compact histidine clusters stabilizing Cu(II) and spaced histidines favoring Zn(II).
Area of Science:
- Biochemistry
- Microbiology
- Bioinorganic Chemistry
Background:
- Copper homeostasis is crucial for bacterial survival, balancing essential roles in respiration with toxicity from excess.
- The CusCFBA efflux system exports copper, but the periplasmic chaperone CusF's response to Cu(II) under oxidative stress remains unclear.
- Understanding CusF's metal-binding adaptability and sequence-dependent selectivity is key to deciphering bacterial copper regulation.
Purpose of the Study:
- To investigate the adaptability of CusF's coordination environment to different metal ions.
- To determine how histidine spacing within CusF mimics influences selectivity for Cu(II) versus Zn(II).
- To explore the structural and electronic properties of CusF-mimicking peptides bound to Cu(II) and Zn(II).
Main Methods:
- Synthesis and characterization of two peptides mimicking CusF metal-binding domains: a compact -HHH- motif and a His/Met-rich site.
- Utilized potentiometry, UV-Vis, CD spectroscopy, ESI-MS, and fluorescence spectroscopy to analyze metal complexes.
- Compared metal binding affinities and coordination environments for Cu(II) and Zn(II) across different peptide architectures.
Main Results:
- Both peptides formed Cu(II) complexes with a [1Nim, 2N-] donor set at physiological pH.
- The compact -HHH- motif peptide showed enhanced stabilization of Cu(II) complexes compared to the His/Met-rich peptide.
- Zn(II) binding differed: three imidazole donors for -HHH- peptide, higher overall affinity with two imidazoles for the His/Met-rich site.
- Fluorescence quenching and red-shifts indicated distinct metal-induced perturbations near tryptophan, with Cu(II) showing stronger effects.
Conclusions:
- Peptide sequence architecture, specifically histidine clustering, significantly governs metal selectivity in CusF mimics.
- Compact histidine arrangements (-HHH-) preferentially stabilize Cu(II), essential for bacterial respiration.
- Spaced histidine residues favor Zn(II) binding, highlighting a mechanism for differential metal ion management.
- Findings provide insights into CusF's role in bacterial copper homeostasis and potential strategies for metal detoxification.
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