title: Outward Rectification of Voltage-Gated K+ Channels Evolved at Least Twice in Life History.
abstract: Voltage-gated potassium (K+) channels are present in all living systems. Despite high structural similarities in the transmembrane domains (TMD), this K+ channel type segregates into at least two main functional categories-hyperpolarization-activated, inward-rectifying (Kin) and depolarization-activated, outward-rectifying (Kout) channels. Voltage-gated K+ channels sense the membrane voltage via a voltage-sensing domain that is connected to the conduction pathway of the channel. It has been shown that the voltage-sensing mechanism is the same in Kin and Kout channels, but its performance results in opposite pore conformations. It is not known how the different coupling of voltage-sensor and pore is implemented. Here, we studied sequence and structural data of voltage-gated K+ channels from animals and plants with emphasis on the property of opposite rectification. We identified structural hotspots that alone allow already the distinction between Kin and Kout channels. Among them is a loop between TMD S5 and the pore that is very short in animal Kout, longer in plant and animal Kin and the longest in plant Kout channels. In combination with further structural and phylogenetic analyses this finding suggests that outward-rectification evolved twice and independently in the animal and plant kingdom.
authors.affiliation: Centro de Bioinformática y Simulación Molecular (CBSM), Universidad de Talca, Talca, Chile.
authors.forename: Janin
authors.initials: J
authors.lastname: Riedelsberger
authors.affiliation: Centro de Bioinformática y Simulación Molecular (CBSM), Universidad de Talca, Talca, Chile; Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Madrid, Spain; Institute for Biochemistry and Biology, University of Potsdam, Potsdam, Germany.
authors.forename: Ingo
authors.initials: I
authors.lastname: Dreyer
authors.affiliation: Centro de Bioinformática y Simulación Molecular (CBSM), Universidad de Talca, Talca, Chile.
authors.forename: Wendy
authors.initials: W
authors.lastname: Gonzalez
mesh_terms: D000818:Animals; D005075:Biological Evolution; D016000:Cluster Analysis; D030541:Databases, Genetic; D008958:Models, Molecular; D010944:Plants / Q000378:metabolism; D024642:Potassium Channels, Voltage-Gated / Q000737:chemistry* / Q000378:metabolism*; D011487:Protein Conformation; D054730:Protein Interaction Domains and Motifs; D013329:Structure-Activity Relationship
chemical_list: D024642:Potassium Channels, Voltage-Gated