title: 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.
abstract: 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 Ca(2+) 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.
authors: Laboratory of Molecular and Cellular Signalling, Department Cellular and Molecular Medicine, Campus Gasthuisberg O/N-1 Bus 802, Herestraat 49, BE-3000 Leuven, Belgium.
authors: Catheleyne
authors: C
authors: D'hondt
authors: Jegan
authors: J
authors: Iyyathurai
authors: Nan
authors: N
authors: Wang
authors: Robert G
authors: RG
authors: Gourdie
authors: Bernard
authors: B
authors: Himpens
authors: Luc
authors: L
authors: Leybaert
authors: Geert
authors: G
authors: Bultynck
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001216:Asparagine / Q000737:chemistry* / Q000235:genetics; D001710:Biotin / Q000737:chemistry; D002118:Calcium / Q000378:metabolism; D002417:Cattle; D018031:Connexin 43 / Q000737:chemistry* / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D011392:Proline / Q000737:chemistry / Q000235:genetics; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013917:Thrombin / Q000737:chemistry
chemical_list: D018031:Connexin 43; D001710:Biotin; D001216:Asparagine; D000255:Adenosine Triphosphate; D011392:Proline; D013917:Thrombin; D002118:Calcium