Comparison of the Structure of a Bacterial Potassium Channel in Both 2D and 3D Crystals

Rita De Zorzi, William V. Nicholson, Stephen J. Tucker, Catherine Vénien-Bryan

Research output: Contribution to journalArticle

Abstract

Inwardly-rectifying potassium (Kir) channels regulate membrane electrical excitability and K+ transport in many cell types where they control such diverse processes as heart rate, vascular tone, insulin secretion and salt/fluid balance. Their physiological importance is highlighted by the fact that genetically inherited defects in Kir channels are responsible for a wide-range of channelopathies. To elucidate how channel function becomes defective in the disease state requires a detailed understanding of channel structure in both the open and closed states, but to date detailed information about the open state structure of the Kir channel is lacking. In this work, we have used EM analysis of 2D crystals of a prokaryotic Kir channel trapped in an open state and compared these results with an open state structure of the same channel that our lab recently determined by X-ray crystallography at 3Å resolution. Intriguingly, the projection maps from the EM experiments suggest a larger opening of the pore in the 2D crystal form compared to that observed in the 3D crystal structure. The organization of these two crystal forms is different and suggests that the 2D crystals may permit stabilisation of an open state structure that is not compatible with 3D crystallisation. These results not only have major implications for our understanding of the open state structure of the Kir channel, but more importantly they demonstrate the general utility and importance of methods such as electron microscopy and 2D crystallography for the study of membrane protein structure.
Original languageEnglish
Pages (from-to)536a
Number of pages1
JournalBiophysical Journal
Volume102
Issue number3
DOIs
Publication statusPublished - 31 Jan 2012

Fingerprint

Channelopathies
Inwardly Rectifying Potassium Channel
Bacterial Structures
Crystallography
Water-Electrolyte Balance
Potassium Channels
X Ray Crystallography
Crystallization
Blood Vessels
Electron Microscopy
Membrane Proteins
Salts
Heart Rate
Insulin
Membranes

Cite this

Zorzi, Rita De ; Nicholson, William V. ; Tucker, Stephen J. ; Vénien-Bryan, Catherine. / Comparison of the Structure of a Bacterial Potassium Channel in Both 2D and 3D Crystals. In: Biophysical Journal. 2012 ; Vol. 102, No. 3. pp. 536a.
@article{151ae884b5514e14803bbfd5c0dae45e,
title = "Comparison of the Structure of a Bacterial Potassium Channel in Both 2D and 3D Crystals",
abstract = "Inwardly-rectifying potassium (Kir) channels regulate membrane electrical excitability and K+ transport in many cell types where they control such diverse processes as heart rate, vascular tone, insulin secretion and salt/fluid balance. Their physiological importance is highlighted by the fact that genetically inherited defects in Kir channels are responsible for a wide-range of channelopathies. To elucidate how channel function becomes defective in the disease state requires a detailed understanding of channel structure in both the open and closed states, but to date detailed information about the open state structure of the Kir channel is lacking. In this work, we have used EM analysis of 2D crystals of a prokaryotic Kir channel trapped in an open state and compared these results with an open state structure of the same channel that our lab recently determined by X-ray crystallography at 3{\AA} resolution. Intriguingly, the projection maps from the EM experiments suggest a larger opening of the pore in the 2D crystal form compared to that observed in the 3D crystal structure. The organization of these two crystal forms is different and suggests that the 2D crystals may permit stabilisation of an open state structure that is not compatible with 3D crystallisation. These results not only have major implications for our understanding of the open state structure of the Kir channel, but more importantly they demonstrate the general utility and importance of methods such as electron microscopy and 2D crystallography for the study of membrane protein structure.",
author = "Zorzi, {Rita De} and Nicholson, {William V.} and Tucker, {Stephen J.} and Catherine V{\'e}nien-Bryan",
year = "2012",
month = "1",
day = "31",
doi = "10.1016/j.bpj.2011.11.2929",
language = "English",
volume = "102",
pages = "536a",
journal = "Biophysical Journal",
issn = "0006-3495",
publisher = "Biophysical Society",
number = "3",

}

Comparison of the Structure of a Bacterial Potassium Channel in Both 2D and 3D Crystals. / Zorzi, Rita De; Nicholson, William V.; Tucker, Stephen J.; Vénien-Bryan, Catherine.

In: Biophysical Journal, Vol. 102, No. 3, 31.01.2012, p. 536a.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Comparison of the Structure of a Bacterial Potassium Channel in Both 2D and 3D Crystals

AU - Zorzi, Rita De

AU - Nicholson, William V.

AU - Tucker, Stephen J.

AU - Vénien-Bryan, Catherine

PY - 2012/1/31

Y1 - 2012/1/31

N2 - Inwardly-rectifying potassium (Kir) channels regulate membrane electrical excitability and K+ transport in many cell types where they control such diverse processes as heart rate, vascular tone, insulin secretion and salt/fluid balance. Their physiological importance is highlighted by the fact that genetically inherited defects in Kir channels are responsible for a wide-range of channelopathies. To elucidate how channel function becomes defective in the disease state requires a detailed understanding of channel structure in both the open and closed states, but to date detailed information about the open state structure of the Kir channel is lacking. In this work, we have used EM analysis of 2D crystals of a prokaryotic Kir channel trapped in an open state and compared these results with an open state structure of the same channel that our lab recently determined by X-ray crystallography at 3Å resolution. Intriguingly, the projection maps from the EM experiments suggest a larger opening of the pore in the 2D crystal form compared to that observed in the 3D crystal structure. The organization of these two crystal forms is different and suggests that the 2D crystals may permit stabilisation of an open state structure that is not compatible with 3D crystallisation. These results not only have major implications for our understanding of the open state structure of the Kir channel, but more importantly they demonstrate the general utility and importance of methods such as electron microscopy and 2D crystallography for the study of membrane protein structure.

AB - Inwardly-rectifying potassium (Kir) channels regulate membrane electrical excitability and K+ transport in many cell types where they control such diverse processes as heart rate, vascular tone, insulin secretion and salt/fluid balance. Their physiological importance is highlighted by the fact that genetically inherited defects in Kir channels are responsible for a wide-range of channelopathies. To elucidate how channel function becomes defective in the disease state requires a detailed understanding of channel structure in both the open and closed states, but to date detailed information about the open state structure of the Kir channel is lacking. In this work, we have used EM analysis of 2D crystals of a prokaryotic Kir channel trapped in an open state and compared these results with an open state structure of the same channel that our lab recently determined by X-ray crystallography at 3Å resolution. Intriguingly, the projection maps from the EM experiments suggest a larger opening of the pore in the 2D crystal form compared to that observed in the 3D crystal structure. The organization of these two crystal forms is different and suggests that the 2D crystals may permit stabilisation of an open state structure that is not compatible with 3D crystallisation. These results not only have major implications for our understanding of the open state structure of the Kir channel, but more importantly they demonstrate the general utility and importance of methods such as electron microscopy and 2D crystallography for the study of membrane protein structure.

U2 - 10.1016/j.bpj.2011.11.2929

DO - 10.1016/j.bpj.2011.11.2929

M3 - Article

VL - 102

SP - 536a

JO - Biophysical Journal

JF - Biophysical Journal

SN - 0006-3495

IS - 3

ER -