Early-stage Determinants of T1-S1 Conformations in Kv1.3 Channels

Area of Science:

• Molecular biology
• Structural biology
• Biophysics

Background:

• Early-stage biogenesis of voltage-gated potassium channels (Kv) is critical for proper protein conformation.
• Kv channels are essential for nerve and immune cell function.

Purpose of the Study:

• To investigate the folding mechanisms and determinants of the Kv1.3 channel during early biogenesis.
• To understand the role of the T1-S1 linker and T1 domain in Kv1.3 assembly.

Main Methods:

• Pegylation (mass-tagging strategy)
• Inter- and intrasubunit crosslinking
• Analysis of T1-S1 linker and T1 domain properties

Main Results:

• Identified dynamic protein-lipid and protein-protein interfaces in the T1-S1 linker.
• Demonstrated that the T1 domain's presence and conformation affect linker properties.
• Showed S0 helical formation occurs early in biogenesis, independent of membranes.
• Found that a T2 domain enhances T1 dimerization and tetramerization.
• Determined that minimal linker residues (12) can facilitate T1 tetramerization.

Conclusions:

• Kv1.3 biogenesis involves dynamic domain interactions, differing from canonical models.
• Domain plasticity in Kv1.3 contributes to channel assembly and may mediate domain-domain communication.
• These findings provide new insights into the structural basis of Kv channel function.