Discovery of a heme-binding domain in a neuronal voltage-gated potassium channel

J Biol Chem. 2020 Sep 18;295(38):13277-13286. doi: 10.1074/jbc.RA120.014150. Epub 2020 Jul 28.

Abstract

The EAG (ether-à-go-go) family of voltage-gated K+ channels are important regulators of neuronal and cardiac action potential firing (excitability) and have major roles in human diseases such as epilepsy, schizophrenia, cancer, and sudden cardiac death. A defining feature of EAG (Kv10-12) channels is a highly conserved domain on the N terminus, known as the eag domain, consisting of a Per-ARNT-Sim (PAS) domain capped by a short sequence containing an amphipathic helix (Cap domain). The PAS and Cap domains are both vital for the normal function of EAG channels. Using heme-affinity pulldown assays and proteomics of lysates from primary cortical neurons, we identified that an EAG channel, hERG3 (Kv11.3), binds to heme. In whole-cell electrophysiology experiments, we identified that heme inhibits hERG3 channel activity. In addition, we expressed the Cap and PAS domain of hERG3 in Escherichia coli and, using spectroscopy and kinetics, identified the PAS domain as the location for heme binding. The results identify heme as a regulator of hERG3 channel activity. These observations are discussed in the context of the emerging role for heme as a regulator of ion channel activity in cells.

Keywords: Cap domain; PAS domain; X-ray crystallography; hERG; hERG3; heme; heme regulation; ion channel; protein crystallization.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cerebral Cortex / chemistry*
  • Cerebral Cortex / metabolism
  • Ether-A-Go-Go Potassium Channels / chemistry*
  • Ether-A-Go-Go Potassium Channels / metabolism
  • Heme / chemistry*
  • Heme / metabolism
  • Humans
  • Neurons / chemistry*
  • Neurons / metabolism
  • Protein Binding
  • Protein Domains

Substances

  • Ether-A-Go-Go Potassium Channels
  • KCNH7 protein, human
  • Heme

Associated data

  • PDB/1V9Y
  • PDB/1DP6
  • PDB/5VA1
  • PDB/4HQA
  • PDB/6Y7Q