The N-terminal domains of Bacillus subtilis CopA do not form a stable complex in the absence of their inter-domain linker

Liang Zhou, Kristine L. Kay, Oliver Hecht, Geoffrey R. Moore, Nick E. Le Brun

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Copper-transporting P-type ATPases, which play important roles in trafficking Cu(I) across membranes for the biogenesis of copper proteins or for copper detoxification, contain a variable number of soluble metal-binding domains at their N-termini. It is increasingly apparent that these play an important role in regulating copper transport in a Cu(I)-responsive manner, but how they do this is unknown. CopA, a Cu(I)-transporter from Bacillus subtilis, contains two N-terminal soluble domains that are closely packed, with inter-domain interactions at two principal regions. Here, we sought to determine the extent to which the domains interact in the absence of their inter-domain covalent linker, and how their Cu(I)-binding properties are affected. Studies of a 1:1 mixture of separate CopAa and CopAb domains showed that the domains do not form a stable complex, with only indirect evidence of a weak interaction between them. Their Cu(I)-binding behaviour was distinct from that of the two domain protein and consistent with a lack of interaction between the domains. Cu(I)-mediated protein association was observed, but this occurred only between domains of the same type. Thus, the inter-domain covalent link between CopAa and CopAb is essential for inter-domain interactions and for Cu(I)-binding behaviour.
Original languageEnglish
Pages (from-to)275-282
Number of pages8
JournalBiochimica et Biophysica Acta (BBA) - Proteins & Proteomics
Issue number2
Early online date14 Nov 2017
Publication statusPublished - Feb 2018


  • Copper trafficking
  • Metallochaperones
  • Homeostasis
  • Metal transport

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