Copper(I) stabilization by cysteine/tryptophan motif in the extracellular domain of Ctr4

Mariko Okada, Takashi Miura

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

Copper transporter Ctr4 of fission yeast has a quasi-palindromic sequence rich in cysteine and aromatic amino acid residues, CX4YWNWYX4C (where X represents any amino acid), in the N-terminal extracellular domain. A 24-mer peptide comprising this sequence is bound to Cu(I) through the cysteine thiolate coordination. Luminescence, UV absorption and resonance Raman spectra of the Cu(I)-peptide complex show that at least one of the two tryptophan side chains is located in close proximity to the thiolate-Cu(I) center and interacts with the Cu(I) ion via π-electrons of the indole ring. Although the thiolates and Cu(I) are oxidized to disulfide and Cu(II), respectively, only very slowly in air-saturated solutions, replacements of the tryptophan residues to phenylalanine significantly accelerate the oxidation reactions. The results obtained indicate that the interaction between Cu(I) and tryptophan via π-electrons plays a significant role in protecting the thiolate-Cu(I) center against the oxidation. The cysteine- and tryptophan-rich quasi-palindromic sequence may be a metal binding motif that stabilizes Cu(I) in the oxidizing extracellular environment.

Original languageEnglish
Pages (from-to)45-49
Number of pages5
JournalJournal of Inorganic Biochemistry
Volume159
DOIs
Publication statusPublished - 2016 Jun 1

Keywords

  • Cation-π interaction
  • Ctr4 copper transporter
  • Cysteine
  • Metal coordination
  • Raman spectroscopy
  • Tryptophan

ASJC Scopus subject areas

  • Biochemistry
  • Inorganic Chemistry

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