title: Multiple interactions between cytoplasmic domains regulate slow deactivation of Kv11.1 channels.
abstract: The intracellular domains of many ion channels are important for fine-tuning their gating kinetics. In Kv11.1 channels, the slow kinetics of channel deactivation, which are critical for their function in the heart, are largely regulated by the N-terminal N-Cap and Per-Arnt-Sim (PAS) domains, as well as the C-terminal cyclic nucleotide-binding homology (cNBH) domain. Here, we use mutant cycle analysis to probe for functional interactions between the N-Cap/PAS domains and the cNBH domain. We identified a specific and stable charge-charge interaction between Arg(56) of the PAS domain and Asp(803) of the cNBH domain, as well an additional interaction between the cNBH domain and the N-Cap, both of which are critical for maintaining slow deactivation kinetics. Furthermore, we found that positively charged arginine residues within the disordered region of the N-Cap interact with negatively charged residues of the C-linker domain. Although this interaction is likely more transient than the PAS-cNBD interaction, it is strong enough to stabilize the open conformation of the channel and thus slow deactivation. These findings provide novel insights into the slow deactivation mechanism of Kv11.1 channels.
authors: From the Victor Chang Cardiac Research Institute and St. Vincent's Clinical School, University of New South Wales, Darlinghurst, New South Wales 2010, Australia.
authors: Chai Ann
authors: CA
authors: Ng
authors: From the Victor Chang Cardiac Research Institute and St. Vincent's Clinical School, University of New South Wales, Darlinghurst, New South Wales 2010, Australia.
authors: Kevin
authors: K
authors: Phan
authors: From the Victor Chang Cardiac Research Institute and St. Vincent's Clinical School, University of New South Wales, Darlinghurst, New South Wales 2010, Australia.
authors: Adam P
authors: AP
authors: Hill
authors: From the Victor Chang Cardiac Research Institute and St. Vincent's Clinical School, University of New South Wales, Darlinghurst, New South Wales 2010, Australia j.vandenberg@victorchang.edu.au.
authors: Jamie I
authors: JI
authors: Vandenberg
authors: From the Victor Chang Cardiac Research Institute and St. Vincent's Clinical School, University of New South Wales, Darlinghurst, New South Wales 2010, Australia.
authors: Matthew D
authors: MD
authors: Perry
mesh_terms: D000818:Animals; D001120:Arginine / Q000737:chemistry / Q000378:metabolism; D001216:Asparagine / Q000737:chemistry / Q000378:metabolism; D001665:Binding Sites; D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D009206:Myocardium / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D054730:Protein Interaction Domains and Motifs / Q000235:genetics*; D017434:Protein Structure, Tertiary; D014982:Xenopus laevis / Q000235:genetics / Q000378:metabolism
chemical_list: D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; C000606913:KCNH2 protein, human; D001216:Asparagine; D001120:Arginine
keywords: Gating; Heart; Ion Channel; Mutagenesis; Potassium Channel; Protein Chimera; Protein Domain; Protein-Protein Interaction; Site-directed Mutagenesis; hERG