Quaternary structure independent folding of voltage-gated ion channel pore domain subunits

Cristina Arrigoni; Marco Lolicato; David Shaya; Ahmed Rohaim; Felix Findeisen; Lam-Kiu Fong; Claire M Colleran; Pawel Dominik; Sangwoo S Kim; Jonathan P Schuermann; William F DeGrado; Michael Grabe; Anthony A Kossiakoff; Daniel L Minor Jr

doi:10.1038/s41594-022-00775-x

Quaternary structure independent folding of voltage-gated ion channel pore domain subunits

Nat Struct Mol Biol. 2022 Jun;29(6):537-548. doi: 10.1038/s41594-022-00775-x. Epub 2022 Jun 2.

Authors

Cristina Arrigoni^{1

2}, Marco Lolicato^{1

2}, David Shaya¹, Ahmed Rohaim¹, Felix Findeisen¹, Lam-Kiu Fong^{1

3}, Claire M Colleran¹, Pawel Dominik⁴, Sangwoo S Kim⁴, Jonathan P Schuermann⁵, William F DeGrado^{1

3}, Michael Grabe^{1

3}, Anthony A Kossiakoff⁴, Daniel L Minor Jr^{6

7

8

9

10}

Affiliations

¹ Cardiovascular Research Institute, University of California, San Francisco, CA, USA.
² Department of Molecular Medicine, University of Pavia, Pavia, Italy.
³ Department of Pharmaceutical Chemistry, University of California, San Francisco, CA, USA.
⁴ Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA.
⁵ Northeastern Collaborative Access Team, Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA.
⁶ Cardiovascular Research Institute, University of California, San Francisco, CA, USA. daniel.minor@ucsf.edu.
⁷ Departments of Biochemistry and Biophysics, and Cellular and Molecular Pharmacology, University of California, San Francisco, CA, USA. daniel.minor@ucsf.edu.
⁸ California Institute for Quantitative Biomedical Research, University of California, San Francisco, CA, USA. daniel.minor@ucsf.edu.
⁹ Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, CA, USA. daniel.minor@ucsf.edu.
¹⁰ Molecular Biophysics and Integrated Bio-imaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA. daniel.minor@ucsf.edu.

Abstract

Every voltage-gated ion channel (VGIC) has a pore domain (PD) made from four subunits, each comprising an antiparallel transmembrane helix pair bridged by a loop. The extent to which PD subunit structure requires quaternary interactions is unclear. Here, we present crystal structures of a set of bacterial voltage-gated sodium channel (BacNa_V) 'pore only' proteins that reveal a surprising collection of non-canonical quaternary arrangements in which the PD tertiary structure is maintained. This context-independent structural robustness, supported by molecular dynamics simulations, indicates that VGIC-PD tertiary structure is independent of quaternary interactions. This fold occurs throughout the VGIC superfamily and in diverse transmembrane and soluble proteins. Strikingly, characterization of PD subunit-binding Fabs indicates that non-canonical quaternary PD conformations can occur in full-length VGICs. Together, our data demonstrate that the VGIC-PD is an autonomously folded unit. This property has implications for VGIC biogenesis, understanding functional states, de novo channel design, and VGIC structural origins.

Publication types

Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Molecular Conformation
Molecular Dynamics Simulation
Voltage-Gated Sodium Channels* / chemistry
Voltage-Gated Sodium Channels* / metabolism

Substances

Voltage-Gated Sodium Channels

Abstract

Publication types

MeSH terms

Substances

Grants and funding