Reply to Pisupati et al.: Evaluating single subunit counting data to find the correct stoichiometry

Möller, Lena; Regnier, Glenn; Labro, Alain J.; Snyders, Dirk J.; Blunck, Rikard

doi:10.1073/pnas.2018077117

Cited by 1 publication

(1 citation statement)

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“…If this salt bridge is important in the tetramer as well as the pentamer that we see here, it would imply that the stoichiometry of Kv2: KvS proteins would be most stable in a 2:2 arrangement. Both 2:2 and 3:1 stoichiometries for Kv2: KvS proteins have been observed in transfected cell models but which state predominates in native channels is unknown [35][36][37][38] .…”

Section: Discussionmentioning

confidence: 99%

Pentameric assembly of the Kv2.1 tetramerization domain

Khan

Schnicker

et al. 2021

Preprint

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The Kv family of voltage-gated potassium channels regulate neuronal excitability. The biophysical characteristic of Kv channels can be matched to the needs of different neurons by forming homotetrameric or heterotetrameric channels within one of four subfamilies. The cytoplasmic tetramerization (T1) domain plays a major role in dictating the compatibility of different Kv subunits. The only Kv subfamily missing a representative structure of the T1 domain is the Kv2 family. We used X-ray crystallography to solve the structure of the human Kv2.1 T1 domain. The structure is similar to other T1 domains but surprisingly formed a pentamer instead of a tetramer. In solution the Kv2.1 T1 domain also formed a pentamer as determined with in-line SEC-MALS-SAXS and negative stain EM. The Kv2.1 T1-T1 interface involves electrostatic interactions including a salt bridge formed by the negative charges in a previously described CDD motif, and inter-subunit coordination of zinc. We show that zinc binding is important for stability. In conclusion, the Kv2.1 T1 domain behaves differently from the other Kv T1 domains which may reflect the versatility of Kv2.1, the only Kv subfamily that can assemble with the regulatory KvS subunits and scaffold ER-plasma membrane contacts.

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Section: Discussionmentioning

confidence: 99%