Structure of the amino terminus of a gap junction protein

Priscilla E.M. Purnick, David C. Benjamin, Vytas K. Verselis, Thaddeus A. Bargiello, Terry L. Dowd

Research output: Contribution to journalArticle

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Abstract

Charged amino acid residues in the amino terminus of gap junction forming proteins (connexins) form part, if not all, of the transjunctional voltage sensor of gap junction channels and play a fundamental role in ion permeation. Results from studies of the voltage dependence of N-terminal mutants predict that residues 1-10 of Group I connexins lie within the channel pore and that the N-terminus forms the channel vestibule by the creation of a turn initiated by the conserved G12 residue. Here we report that intercellular channels containing mutations of G12 in Cx32 to residues that are likely to interfere with flexibility of this locus (G12S, G12Y, and G12V) do not express junctional currents, whereas a connexin containing a proline residue at G12 (Cx32G12P), which is expected to maintain a structure similar to that of the G12 locus, forms nearly wild-type channels. We have solved the structure of an N-terminal peptide of Cx26 (MD-WGTLQSILGGVNK) using 1H 2D NMR. The peptide contains two structured domains connected by a flexible hinge (domain-hinge-domain motif) that would allow the placement of the amino terminus within the channel pore. Residues 1-10 adopt a helical conformation and line the channel entrance while residues 12-15 form an open turn. Overall, there is good agreement between the structural and dynamic features of the N-terminal peptide provided by NMR and the functional studies of the voltage dependence of channels formed by wild-type and N-terminal mutations.

Original languageEnglish (US)
Pages (from-to)181-190
Number of pages10
JournalArchives of Biochemistry and Biophysics
Volume381
Issue number2
DOIs
Publication statusPublished - Sep 15 2000

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Keywords

  • Atomic resolution structure
  • Connexins
  • Ion channels
  • NMR
  • Structure-function
  • Voltage-dependent gating

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology

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