Structural and functional characterization of an anesthetic binding site in the second cysteine-rich domain of protein kinase Cδ*

Biophys J. 2012 Dec 5;103(11):2331-40. doi: 10.1016/j.bpj.2012.10.034.

Abstract

Elucidating the principles governing anesthetic-protein interactions requires structural determinations at high resolutions not yet achieved with ion channels. Protein kinase C (PKC) activity is modulated by general anesthetics. We solved the structure of the phorbol-binding domain (C1B) of PKCδ complexed with an ether (methoxymethylcycloprane) and with an alcohol (cyclopropylmethanol) at 1.36-Å resolution. The cyclopropane rings of both agents displace a single water molecule in a surface pocket adjacent to the phorbol-binding site, making van der Waals contacts with the backbone and/or side chains of residues Asn-237 to Ser-240. Surprisingly, two water molecules anchored in a hydrogen-bonded chain between Thr-242 and Lys-260 impart elasticity to one side of the binding pocket. The cyclopropane ring takes part in π-acceptor hydrogen bonds with the amide of Met-239. There is a crucial hydrogen bond between the oxygen atoms of the anesthetics and the hydroxyl of Tyr-236. A Tyr-236-Phe mutation results in loss of binding. Thus, both van der Waals interactions and hydrogen-bonding are essential for binding to occur. Ethanol failed to bind because it is too short to benefit from both interactions. Cyclopropylmethanol inhibited phorbol-ester-induced PKCδ activity, but failed to do so in PKCδ containing the Tyr-236-Phe mutation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Anesthetics, General / chemistry*
  • Binding Sites
  • Cyclopropanes / chemistry*
  • Cysteine / chemistry*
  • Ethers / chemistry*
  • Humans
  • Methanol / analogs & derivatives*
  • Methanol / chemistry
  • Protein Binding
  • Protein Conformation
  • Protein Kinase C-delta / chemistry*
  • Protein Kinase C-delta / ultrastructure*
  • Protein Structure, Tertiary
  • Structure-Activity Relationship

Substances

  • Anesthetics, General
  • Cyclopropanes
  • Ethers
  • cyclopropylcarbinol
  • Protein Kinase C-delta
  • Cysteine
  • Methanol

Associated data

  • PDB/3UEJ
  • PDB/3UEY
  • PDB/3UGI
  • PDB/3UGL