PH-regulated metal-ligand switching in the HM loop of ATP7A

A new paradigm for metal transfer chemistry

Chelsey D. Kline, Benjamin F. Gambill, Mary Mayfield, Svetlana Lutsenko, Ninian Blackburn

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Cuproproteins such as PHM and DBM mature in late endosomal vesicles of the mammalian secretory pathway where changes in vesicle pH are employed for sorting and post-translational processing. Colocation with the P1B-type ATPase ATP7A suggests that the latter is the source of copper and supports a mechanism where selectivity in metal transfer is achieved by spatial colocation of partner proteins in their specific organelles or vesicles. In previous work we have suggested that a lumenal loop sequence located between trans-membrane helices TM1 and TM2 of the ATPase, and containing five histidines and four methionines, acts as an organelle-specific chaperone for metallation of the cuproproteins. The hypothesis posits that the pH of the vesicle regulates copper ligation and loop conformation via a mechanism which involves His to Met ligand switching induced by histidine protonation. Here we report the effect of pH on the HM loop copper coordination using X-ray absorption spectroscopy (XAS), and show via selenium substitution of the Met residues that the HM loop undergoes similar conformational switching to that found earlier for its partner PHM. We hypothesize that in the absence of specific chaperones, HM motifs provide a template for building a flexible, pH-sensitive transfer site whose structure and function can be regulated to accommodate the different active site structural elements and pH environments of its partner proteins.

Original languageEnglish (US)
Pages (from-to)729-733
Number of pages5
JournalMetallomics
Volume8
Issue number8
DOIs
StatePublished - Aug 1 2016

Fingerprint

Copper
Metals
Ligands
Histidine
Adenosine Triphosphatases
Proteins
X ray absorption spectroscopy
Organelles
Protonation
Selenium
Sorting
Methionine
X-Ray Absorption Spectroscopy
Conformations
Substitution reactions
Secretory Pathway
Membranes
Ligation
Processing
Catalytic Domain

ASJC Scopus subject areas

  • Biomaterials
  • Metals and Alloys
  • Chemistry (miscellaneous)
  • Biochemistry
  • Biophysics

Cite this

PH-regulated metal-ligand switching in the HM loop of ATP7A : A new paradigm for metal transfer chemistry. / Kline, Chelsey D.; Gambill, Benjamin F.; Mayfield, Mary; Lutsenko, Svetlana; Blackburn, Ninian.

In: Metallomics, Vol. 8, No. 8, 01.08.2016, p. 729-733.

Research output: Contribution to journalArticle

Kline, Chelsey D. ; Gambill, Benjamin F. ; Mayfield, Mary ; Lutsenko, Svetlana ; Blackburn, Ninian. / PH-regulated metal-ligand switching in the HM loop of ATP7A : A new paradigm for metal transfer chemistry. In: Metallomics. 2016 ; Vol. 8, No. 8. pp. 729-733.
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