Trafficking defects in PAS domain mutant Kv11.1 channels: roles of reduced domain stability and altered domain-domain interactions

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 Per-Arnt-Sim (PAS) 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 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 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 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.

Source: BJ Cell - May 31, 2013 Category: Biochemistry Authors: Y Ke, C Ann Ng, M J Hunter, S A Mann, J Heide, A P Hill, J I Vandenberg Tags: BJ Cell Source Type: research