title: Mapping of interactions between the N- and C-termini and the channel core in HERG K+ channels.
abstract: The characteristic gating properties of the HERG [human eag (ether-a-go-go)-related gene] potassium channel determine its contribution to cardiac repolarization and in setting the electrical behaviour of a variety of cells. In the present study we analysed, using a site-directed cysteine and disulfide chemistry approach, whether the eag/PAS (Per/Arnt/Sim) and proximal domains at the HERG N-terminus exert a role in controlling the access of the N-terminal flexible tail to its binding site in the channel core for interaction with the gating machinery. Whereas the eag/PAS domain is necessary for disulfide bridging, plus the cysteine residues introduced at positions 3 and 542 of the HERG sequence, the presence of the proximal domain seems to be dispensable. The state-dependent formation of a disulfide bridge between Cys3 and an endogenous cysteine residue at position 723 in the C-terminal C-linker suggests that the N-terminal tail of HERG can also get into close proximity with the C-linker structures located at the bottom of helix S6. Therefore the intrinsic flexibility of the N-tail and its proximity to both the S4-S5 loop and the C-linker may dynamically contribute to the modulation of HERG channel gating.
authors: Department of Biochemistry and Molecular Biology, University of Oviedo, 33006 Oviedo, Spain. pdelapena@uniovi.es
authors: Pilar
authors: P
authors: de la Peña
authors: Angeles
authors: A
authors: Machín
authors: Jorge
authors: J
authors: Fernández-Trillo
authors: Pedro
authors: P
authors: Domínguez
authors: Francisco
authors: F
authors: Barros
mesh_terms: D000818:Animals; D001665:Binding Sites; D003545:Cysteine / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004220:Disulfides / Q000737:chemistry; D051638:Ether-A-Go-Go Potassium Channels / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D015640:Ion Channel Gating; D008564:Membrane Potentials / Q000502:physiology*; D008845:Microinjections; D016297:Mutagenesis, Site-Directed; D009865:Oocytes / Q000166:cytology / Q000378:metabolism*; D010084:Oxidation-Reduction; D018408:Patch-Clamp Techniques; D010957:Plasmids; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013329:Structure-Activity Relationship; D014982:Xenopus laevis
chemical_list: D004220:Disulfides; D051638:Ether-A-Go-Go Potassium Channels; D003545:Cysteine