title: Changes in channel trafficking and protein stability caused by LQT2 mutations in the PAS domain of the HERG channel.
abstract: Inherited human long-QT2 syndrome (LQTS) results from mutations in the gene encoding the HERG channel. Several LQT2-associated mutations have been mapped to the amino terminal cytoplasmic Per-Arnt-Sim (PAS) domain of the HERG1a channel subunit. Here we have characterized the trafficking properties of some LQT2-associated PAS domain mutants and analyzed rescue of the trafficking mutants by low temperature (27°C) or by the pore blocker drug E4031. We show that the LQT2-associated mutations in the PAS domain of the HERG channel display molecular properties that are distinct from the properties of LQT2-associated mutations in the trans-membrane region. Unlike the latter, many of the tested PAS domain LQT2-associated mutations do not result in trafficking deficiency of the channel. Moreover, the majority of the PAS domain mutations that cause trafficking deficiencies are not rescued by a pore blocking drug. We have also explored the in vitro folding stability properties of isolated mutant PAS domain proteins using a thermal unfolding fluorescence assay and a chemical unfolding assay.
authors.affiliation: IBMC, Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal. harleyca@ibmc.up.pt
authors.forename: Carol A
authors.initials: CA
authors.lastname: Harley
authors.forename: Catarina S H
authors.initials: CS
authors.lastname: Jesus
authors.forename: Ricardo
authors.initials: R
authors.lastname: Carvalho
authors.forename: Rui M M
authors.initials: RM
authors.lastname: Brito
authors.forename: João H
authors.initials: JH
authors.lastname: Morais-Cabral
mesh_terms: D002942:Circular Dichroism; D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels / Q000737:chemistry / Q000235:genetics*; D006026:Glycoside Hydrolases / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D008133:Long QT Syndrome / Q000235:genetics*; D009154:Mutation; D010641:Phenotype; D011489:Protein Denaturation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D013696:Temperature; D013816:Thermodynamics; D014466:Ultraviolet Rays
chemical_list: D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; C000606913:KCNH2 protein, human; D006026:Glycoside Hydrolases