Molecular basis of inward rectification: Polyamine interaction sites located by combined channel and ligand mutagenesis

Harley T. Kurata, L. Revell Phillips, Thierry Rose, Gildas Loussouarn, Stefan Herlitze, Hariolf Fritzenschaft, Decha Enkvetchakul, Colin G. Nichols, Thomas Baukrowitz

Research output: Contribution to journalArticlepeer-review

47 Scopus citations

Abstract

Polyamines cause inward rectification of (Kir) K+ channels, but the mechanism is controversial. We employed scanning mutagenesis of Kir6.2, and a structural series of blocking diamines, to combinatorially examine the role of both channel and blocker charges. We find that introduced glutamates at any pore-facing residue in the inner cavity, up to and including the entrance to the selectivity filter, can confer strong rectification. As these negative charges are moved higher (toward the selectivity filter), or lower (toward the cytoplasm), they preferentially enhance the potency of block by shorter, or longer, diamines, respectively. MTSEA+ modification of engineered cysteines in the inner cavity reduces rectification, but modification below the inner cavity slows spermine entry and exit, without changing steady-state rectification. The data provide a coherent explanation of classical strong rectification as the result of polyamine block in the inner cavity and selectivity filter.

Original languageEnglish
Pages (from-to)541-554
Number of pages14
JournalJournal of General Physiology
Volume124
Issue number5
DOIs
StatePublished - Nov 2004

Keywords

  • Diamine
  • Inward rectifier
  • Rectification
  • Selectivity filter
  • Spermine

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