TY - JOUR
T1 - Structural studies of the N-terminus of Connexin 32 using 1H NMR spectroscopy
AU - Kalmatsky, B. D.
AU - Bhagan, S.
AU - Tang, Q.
AU - Bargiello, T. A.
AU - Dowd, T. L.
N1 - Funding Information:
We thank Drs. S. Cahill and Mark Girvin for helpful discussions and technical assistance. This work was supported by NIH grant GM46889 to T.A.B., and subcontract to T.L.D.
PY - 2009/10/1
Y1 - 2009/10/1
N2 - The amino terminus of gap junction proteins, connexins, plays a fundamental role in voltage gating and ion permeation. We have previously shown with 1H NMR that the structure of the N-terminus of a representative connexin molecule contains a flexible turn around glycine 12 [P.E. Purnick, D.C. Benjamin, V.K. Verselis, T.A. Bargiello, T.L. Dowd, Arch. Biochem. Biophys. 381 (2000) 181-190] allowing the N-terminus to reside at the cytoplasmic entry of the channel forming a voltage-sensor. Previous functional studies or neuropathies have shown that the mutation G12Y and G12S form non-functional channels while functional channels are formed from G12P. Using 2D 1H NMR we show that similar to G12, the structure of the G12P mutant contains a more flexible turn around residue 12, whereas the G12S and G12Y mutants contain tighter, helical turns in this region. These results suggest an unconstrained turn is required around residue 12 to position the N-terminus within the pore allowing the formation of the cytoplasmic channel vestibule, which appears to be critical for proper channel function.
AB - The amino terminus of gap junction proteins, connexins, plays a fundamental role in voltage gating and ion permeation. We have previously shown with 1H NMR that the structure of the N-terminus of a representative connexin molecule contains a flexible turn around glycine 12 [P.E. Purnick, D.C. Benjamin, V.K. Verselis, T.A. Bargiello, T.L. Dowd, Arch. Biochem. Biophys. 381 (2000) 181-190] allowing the N-terminus to reside at the cytoplasmic entry of the channel forming a voltage-sensor. Previous functional studies or neuropathies have shown that the mutation G12Y and G12S form non-functional channels while functional channels are formed from G12P. Using 2D 1H NMR we show that similar to G12, the structure of the G12P mutant contains a more flexible turn around residue 12, whereas the G12S and G12Y mutants contain tighter, helical turns in this region. These results suggest an unconstrained turn is required around residue 12 to position the N-terminus within the pore allowing the formation of the cytoplasmic channel vestibule, which appears to be critical for proper channel function.
KW - Atomic resolution structure
KW - Connexins
KW - Ion channels
KW - NMR
KW - Protein structure and function
KW - Structure-function
KW - Voltage dependent gating
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U2 - 10.1016/j.abb.2009.07.015
DO - 10.1016/j.abb.2009.07.015
M3 - Article
C2 - 19638273
AN - SCOPUS:70349445265
SN - 0003-9861
VL - 490
SP - 9
EP - 16
JO - Archives of Biochemistry and Biophysics
JF - Archives of Biochemistry and Biophysics
IS - 1
ER -