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Secondary structural analysis of the carboxyl‐terminal domain from different connexin isoforms
Author(s) -
Spagnol Gaëlle,
AlMugotir Mona,
Kopanic Jennifer L.,
Zach Sydney,
Li Hanjun,
Trease Andrew J.,
Stauch Kelly L.,
Grosely Rosslyn,
Cervantes Matthew,
Sorgen Paul L.
Publication year - 2016
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.22762
Subject(s) - chemistry , terminal (telecommunication) , gene isoform , connexin , domain (mathematical analysis) , focus (optics) , biophysics , biochemistry , stereochemistry , gap junction , telecommunications , intracellular , biology , gene , mathematical analysis , physics , mathematics , computer science , optics
The connexin carboxyl‐terminal (CxCT) domain plays a role in the trafficking, localization, and turnover of gap junction channels, as well as the level of gap junction intercellular communication via numerous post‐translational modifications and protein–protein interactions. As a key player in the regulation of gap junctions, the CT presents itself as a target for manipulation intended to modify function. Specific to intrinsically disordered proteins, identifying residues whose secondary structure can be manipulated will be critical toward unlocking the therapeutic potential of the CxCT domain. To accomplish this goal, we used biophysical methods to characterize CxCT domains attached to their fourth transmembrane domain (TM4). Circular dichroism and nuclear magnetic resonance were complementary in demonstrating the connexin isoforms that form the greatest amount of α‐helical structure in their CT domain (Cx45 > Cx43 > Cx32 > Cx50 > Cx37 ≈ Cx40 ≈ Cx26). Studies compared the influence of 2,2,2‐trifluoroethanol, pH, phosphorylation, and mutations (Cx32, X‐linked Charcot‐Marie Tooth disease; Cx26, hearing loss) on the TM4‐CxCT structure. While pH modestly influences the CT structure, a major structural change was associated with phosphomimetic substitutions. Since most connexin CT domains are phosphorylated throughout their life cycle, studies of phospho‐TM4‐CxCT isoforms will be critical toward understanding the role that structure plays in regulating gap junction function. © 2015 Wiley Periodicals, Inc. Biopolymers 105: 143–162, 2016.