EPR Spectroscopy Targets Structural Changes in the E. coli Membrane Fusion CusB upon Cu(I) Binding

Aviv Meir, Ahmad Abdelhai, Yoni Moskovitz, Sharon Ruthstein

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Bacterial cells have developed sophisticated systems to deal with the toxicity of metal ions. Escherichia coli CusCFBA is a complex efflux system, responsible for transferring Cu(I) and Ag(I) ions; this system, located in the periplasm, involves four proteins, CusA, CusB, CusC, and CusF. CusA, CusB, and CusC are connected to one another in an oligomerization ratio of 3:6:3 CusA/CusB/CusC to form the CusCBA periplasm membrane transporter. CusB is an adaptor protein that connects the two membrane proteins CusA (inner membrane) and CusC (outer membrane). CusF is a metallochaperone that transfers Cu(I) and Ag(I) to the CusCBA transporter from the periplasm. The crystal structures of CusB, CusC, CusF, and the CusBA complex have been resolved, shedding some light on the efflux mechanism underlying this intriguing system. However, since CusB is an adaptor protein, its role in operating this system is significant, and should be understood in detail. Here, we utilize EPR spectroscopy to target the conformational changes that take place in the full CusB protein upon binding Cu(I). We reveal that CusB is a dimer in solution, and that the orientation of one molecule with respect to the other molecule changes upon Cu(I) coordination, resulting in a more compact CusB structure. These structural and topological changes upon Cu(I) binding probably play the role of a switch for opening the channel and transferring metal ions from CusB to CusC and out of the cell.

Original languageEnglish
Pages (from-to)2494-2502
Number of pages9
JournalBiophysical Journal
Issue number12
StatePublished - 20 Jun 2017

Bibliographical note

Publisher Copyright:
© 2017 Biophysical Society


This study was supported by a Marie Curie Career Integration Grant 303636, and by the Israel Science Foundation (grant 176/16). The Elexsys E580 Bruker EPR spectrometer was partially supported by the Israel Science Foundation (grant 564/12).

FundersFunder number
Marie Curie303636
Israel Science Foundation176/16, 564/12


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