IBMC, Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.
PLoS One. 2012;7(3):e32654. doi: 10.1371/journal.pone.0032654. Epub 2012 Mar 2.
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.
遗传性长 QT 综合征 2 型（LQTS2）是由编码 HERG 通道的基因突变引起的。一些与 LQT2 相关的突变已被定位到 HERG1a 通道亚基的氨基末端细胞质 Per-Arnt-Sim（PAS）结构域。在这里，我们对一些与 LQT2 相关的 PAS 结构域突变体的转运特性进行了表征，并分析了低温（27°C）或孔阻断药物 E4031 对转运突变体的挽救作用。我们表明，HERG 通道 PAS 结构域中的 LQT2 相关突变显示出与跨膜区域中 LQT2 相关突变不同的分子特性。与后者不同，许多经过测试的 PAS 结构域 LQT2 相关突变不会导致通道的转运缺陷。此外，引起转运缺陷的大多数 PAS 结构域突变不能被孔阻塞药物挽救。我们还使用热变性荧光分析和化学变性分析，探讨了分离的突变 PAS 结构域蛋白的体外折叠稳定性特性。
