Cd2+ as a Ca2+ Surrogate in Protein–Membrane Interactions: Isostructural but Not Isofunctional Academic Article uri icon

abstract

  • Due to its favorable spectroscopic properties, Cd(2+) is frequently used as a probe of Ca(2+) sites in proteins. We investigate the ability of Cd(2+) to act as a structural and functional surrogate of Ca(2+) in protein-membrane interactions. C2 domain from protein kinase Cα (C2α) was chosen as a paradigm for the Ca(2+)-dependent phosphatidylserine-binding peripheral membrane domains. We identified the Cd(2+)-binding sites of C2α using NMR spectroscopy, determined the 1.6 Å crystal structure of Cd(2+)-bound C2α, and characterized metal-ion-dependent interactions between C2α and phospholipid membranes using fluorescence spectroscopy and ultracentrifugation experiments. We show that Cd(2+) forms a tight complex with the membrane-binding loops of C2α but is unable to support its membrane-binding function. This is in sharp contrast with Pb(2+), which is almost as effective as Ca(2+) in driving the C2α-membrane association process. Our results provide the first direct evidence for the specific role of divalent metal ions in mediating protein-membrane interactions, have important implications for metal substitution studies in proteins, and illustrate the potential diversity of functional responses caused by toxic metal ions.

altmetric score

  • 1

author list (cited authors)

  • Morales, K. A., Yang, Y., Long, Z., Li, P., Taylor, A. B., Hart, P. J., & Igumenova, T. I.

citation count

  • 9

complete list of authors

  • Morales, Krystal A||Yang, Yuan||Long, Zheng||Li, Pingwei||Taylor, Alexander B||Hart, P John||Igumenova, Tatyana I

publication date

  • August 2013