Negatively charged residues (Asp378 and Asp379) in the last ten amino acids of the C-terminal tail of Cx43 hemichannels are essential for loop/tail interactions

作者：D' hondt Catheleyne; Iyyathurai Jegan; Wang Nan; Gourdie Robert G; Himpens Bernard; Leybaert Luc; Bultynck Geert^*

来源：Biochemical and Biophysical Research Communications, 2013, 432(4): 707-712.

DOI：10.1016/j.bbrc.2013.01.066

• Connexin
• Hemichannels
• Peptides
• ATP release
• Ca2+-wave propagation

Connexin 43 (Cx43)-hemichannel activity is controlled by intramolecular interactions between cytoplasmic loop and C-terminal tail. We previously identified the last 10 amino acids of the C-terminal tail of Cx43 as essential for Cx43-hemichannel activity. We developed a cell-permeable peptide covering this sequence (TAT-Cx43CT). In this study, we examined the critical molecular determinants in TAT-Cx43CT to restore Cx43-hemichannel activity. Using amino acid substitutions in TAT-Cx43CT, we identified the two aspartate (Asp378 and Asp379) and two proline (Pro375 and Pro377) residues as critical for TAT-Cx43CT activity, since TAT-Cx43CT(DD/AA) and TAT-Cx43CT(PP/GG) did not overcome the inhibition of Cx43-hemichannel activity induced by thrombin, micromolar cytoplasmic Ca2+ concentration or truncation of Cx43 at M-239. Consistent with this, we found that biotin-Cx43CT(DD/AA) was much less efficient than biotin-Cx43CT to bind the purified CL domain of Cx43 in surface plasmon resonance experiments. In conclusion, we postulate that Asp378 and Asp379 in the C-terminal part of Cx43 are essential for loop/tail interactions in Cx43 hemichannels, while Pro375 and Pro377 may help to properly coordinate the critical Asp residues.

• 出版日期2013-3-22