The structural flexibility of the human copper chaperone Atox1: Insights from combined pulsed EPR studies and computations

Ariel R. Levy, Meital Turgeman, Lada Gevorkyan-Aiapetov, Sharon Ruthstein

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Metallochaperones are responsible for shuttling metal ions to target proteins. Thus, a metallochaperone's structure must be sufficiently flexible both to hold onto its ion while traversing the cytoplasm and to transfer the ion to or from a partner protein. Here, we sought to shed light on the structure of Atox1, a metallochaperone involved in the human copper regulation system. Atox1 shuttles copper ions from the main copper transporter, Ctr1, to the ATP7b transporter in the Golgi apparatus. Conventional biophysical tools such as X-ray or NMR cannot always target the various conformational states of metallochaperones, owing to a requirement for crystallography or low sensitivity and resolution. Electron paramagnetic resonance (EPR) spectroscopy has recently emerged as a powerful tool for resolving biological reactions and mechanisms in solution. When coupled with computational methods, EPR with site-directed spin labeling and nanoscale distance measurements can provide structural information on a protein or protein complex in solution. We use these methods to show that Atox1 can accommodate at least four different conformations in the apo state (unbound to copper), and two different conformations in the holo state (bound to copper). We also demonstrate that the structure of Atox1 in the holo form is more compact than in the apo form. Our data provide insight regarding the structural mechanisms through which Atox1 can fulfill its dual role of copper binding and transfer.

Original languageEnglish
Pages (from-to)1609-1618
Number of pages10
JournalProtein Science
Volume26
Issue number8
DOIs
StatePublished - 1 Aug 2017

Bibliographical note

Publisher Copyright:
© 2017 The Protein Society

Funding

This study was supported by the Israel Science Foundation, grant no. 280/12. The Elexsys E580 Bruker EPR spectrometer was partially supported by the Israel Science Foundation, grant no. 564/12.

FundersFunder number
Israel Science Foundation280/12, 564/12

    Keywords

    • Atox1
    • DEER
    • ENM
    • copper metallochaperone
    • protein dynamics
    • structural flexibility

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