The Effect of Ancestral Mutations in the Kv2.1 Ion Channel T1 Domain on Functional Assembly: Insight into the Phenotypic Evolution of Neuronal Ion Channel Subfamilies
The Kv2 subfamily of tetrameric Shaker-like voltage-gated K+ (Kv) ion channels is essential in the function of action potentials in mammalian neurons by producing delayed-rectifier currents. Shaker-like Kv channels are characterized by their cytoplasmic N-terminal T1 domain that drives posttranslational channel tetramer assembly. Diverse currents can be achieved through co-expression with regulatory (R) subunits with self-incompatible T1 domains that form obligate heteromers favoring 3:1R stoichiometries. Four ancestral point mutations from the Kv2.1 to Kv6.4 (an R gene) T1 domains have been identified in mammalian lineages and were inserted into wild-type (WT) Kv2.1 sequences. To determine the effect of the mutations on channel assembly, WT and mutant Kv2.1 sequences have been modeled into homotetramers and 3:1R heterotetramers with Kv6.4 to compare the average fractional occupancies across symmetrical subunit interfaces in molecular dynamics (MD) simulations. The purpose was to gain insight into how and when these regulatory subunits evolved, why they have been conserved in certain animals, and to establish a base for functional analysis in Xenopus laevis oocytes using voltage clamp techniques. The mutant channels were predicted to lose assembly function from the four point mutations but the bond analyses from the MD simulations did not fully support that prediction. Total occupancy decreased in the mutant forms, but it is uncertain if the lower occupancies would lead to significantly less assembly. Further mutations may need to be considered, and functional analysis must be performed to compare with simulation results to support our findings.
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| Work Title | The Effect of Ancestral Mutations in the Kv2.1 Ion Channel T1 Domain on Functional Assembly: Insight into the Phenotypic Evolution of Neuronal Ion Channel Subfamilies |
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| License | CC0 1.0 (Public Domain Dedication) |
| Work Type | Research Paper |
| Publication Date | December 13, 2024 |
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| Deposited | December 13, 2024 |
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