Insight into the cation-π interaction at the metal binding site of the copper metallochaperone CusF. Academic Article uri icon

abstract

  • The periplasmic Cu(+)/Ag(+) chaperone CusF features a novel cation-π interaction between a Cu(+)/Ag(+) ion and Trp44 at the metal binding site. The nature and strength of the Cu(+)/Ag(+)-Trp44 interactions were investigated using computational methodologies. Quantum-mechanical (QM) calculations showed that the Cu(+) and Ag(+) interactions with Trp44 are of similar strength (~14 kcal/mol) and bond order. Quantum-mechanical/molecular-mechanical (QM/MM) calculations showed that Cu(+) binds in a distorted tetrahedral coordination environment in the Trp44Met mutant, which lacks the cation-π interaction. Molecular dynamics (MD) simulations of CusF in the apo and Cu(+)-bound states emphasized the importance of the Cu(+)-Trp44 interaction in protecting Cu(+) from water oxidation. The protein structure does not change over the time scale of hundreds of nanoseconds in the metal-bound state. The metal recognition site exhibits small motions in the apo state but remains largely preorganized toward metal binding. Trp44 remains oriented to form the cation-π interaction in the apo state and faces an energetic penalty to move away from the metal ion. Cu(+) binding quenches the protein's internal motions in regions linked to binding CusB, suggesting that protein motions play an essential role in Cu(+) transfer to CusB.

published proceedings

  • J Am Chem Soc

altmetric score

  • 1.35

author list (cited authors)

  • Chakravorty, D. K., Wang, B., Ucisik, M. N., & Merz, K. M

citation count

  • 42

complete list of authors

  • Chakravorty, Dhruva K||Wang, Bing||Ucisik, Melek N||Merz, Kenneth M

publication date

  • December 2011