TY - JOUR
T1 - Structure of the amino terminus of a gap junction protein
AU - Purnick, Priscilla E.M.
AU - Benjamin, David C.
AU - Verselis, Vytas K.
AU - Bargiello, Thaddeus A.
AU - Dowd, Terry L.
N1 - Funding Information:
We thank Drs. M. Girvin, S. Cahill, and S. Almo for helpful discussions and Dr. M. Bennett for comments on the manuscript. This work was supported by NIH Grant GM46889 to T.A.B. and ES09032 to T.L.D. P.E.M.P. was supported by a NIH predoctoral training grant (DK07513).
PY - 2000/9/15
Y1 - 2000/9/15
N2 - 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.
AB - 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.
KW - Atomic resolution structure
KW - Connexins
KW - Ion channels
KW - NMR
KW - Structure-function
KW - Voltage-dependent gating
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U2 - 10.1006/abbi.2000.1989
DO - 10.1006/abbi.2000.1989
M3 - Article
C2 - 11032405
AN - SCOPUS:0034664682
SN - 0003-9861
VL - 381
SP - 181
EP - 190
JO - Archives of Biochemistry and Biophysics
JF - Archives of Biochemistry and Biophysics
IS - 2
ER -