title: Trafficking defects in PAS domain mutant Kv11.1 channels: roles of reduced domain stability and altered domain-domain interactions.
abstract: Loss of Kv11.1 potassium channel function is the underlying cause of pathology in long-QT syndrome type 2, one of the commonest causes of sudden cardiac death in the young. Previous studies have identified the cytosolic PAS (Per/Arnt/Sim) domain as a hotspot for mutations that cause Kv11.1 trafficking defects. To investigate the underlying basis of this observation, we have quantified the effect of mutants on domain folding as well as interactions between the PAS domain and the remainder of the channel. Apart from R56Q, all mutants impaired the thermostability of the isolated PAS domain. Six mutants, located in the vicinity of a hydrophobic patch on the PAS domain surface, also affected binding of the isolated PAS domain to an N-terminal truncated hERG (human ether-a-go-go-related gene) channel. Conversely, four other surface mutants (C64Y, T65P, A78P and I96T) and one buried mutant (L86R) did not prevent the isolated PAS domain binding to the truncated channels. Our results highlight a critical role for interactions between the PAS domain and the remainder of the channel in the hERG assembly and that mutants that affect PAS domain interactions with the remainder of the channel have a more severe trafficking defect than that caused by domain unfolding alone.
authors.affiliation: Mark Cowley Lidwill Research Program in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia.
authors.forename: Ying
authors.initials: Y
authors.lastname: Ke
authors.forename: Chai Ann
authors.initials: CA
authors.lastname: Ng
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Hunter
authors.forename: Stefan A
authors.initials: SA
authors.lastname: Mann
authors.forename: Juliane
authors.initials: J
authors.lastname: Heide
authors.forename: Adam P
authors.initials: AP
authors.lastname: Hill
authors.forename: Jamie I
authors.initials: JI
authors.lastname: Vandenberg
mesh_terms: D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D005260:Female; D057809:HEK293 Cells; D006801:Humans; D009154:Mutation / Q000235:genetics*; D011485:Protein Binding / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D021381:Protein Transport / Q000235:genetics; D014982:Xenopus laevis
chemical_list: D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; C000606913:KCNH2 protein, human; C116037:PAS domain kinases; D017346:Protein Serine-Threonine Kinases