8TME

Cryo-EM structure of CorA in complex with conformation-specific synthetic antibody C18 and 100 uM MgCl2, State MG0.1-1B

Summary for 8TME

• Entry DOI: 10.2210/pdb8tme/pdb
• EMDB information: 41386
• Descriptor: sAB C18 Light Chain, sAB C18 Heavy Chain, Cobalt/magnesium transport protein CorA, ... (4 entities in total)
• Functional Keywords: ion channel, magnesium channel, membrane protein
• Biological source: Homo sapiens; More
• Total number of polymer chains: 7
• Total formula weight: 268898.73

Authors

Erramilli, S.K.,Perozo, E.,Kossiakoff, A.A. (deposition date: 2023-07-29, release date: 2025-02-12, Last modification date: 2026-02-25)

Primary citation

Erramilli, S.K.,Nosol, K.,Pietrzak-Lichwa, K.,Schmandt, N.,Li, T.,Tokarz, P.,Hou, J.,Zhao, M.,Perozo, E.,Kossiakoff, A.A.
Conformational ensembles of the magnesium channel CorA reveal structural basis for channel gating.
Proc.Natl.Acad.Sci.USA, 123:e2512532123-e2512532123, 2026

PubMed Abstract: In prokaryotes, CorA is the primary influx pathway for magnesium, a critical divalent cation in cellular physiology and biochemistry. Mechanistic studies show that homopentameric CorA is regulated through an intracellular [Mg]-dependent negative feedback loop, involving the asymmetric participation of individual subunits. To understand the connection between asymmetry and activation, we used single-particle cryo-EM to solve sixteen structures of nanodisc-reconstituted CorA. We utilized conformation-specific synthetic antibodies to stabilize subtle but significant conformational differences in the cryo-EM structures. Our results demonstrate that CorA exists as a set of conformational ensembles, where population size inversely correlates with intracellular Mg concentration. These ensembles include channels with a variety of pore conformations, both constricted and dilated, suggesting a spectrum of active CorA functional states. The ensembles connect asymmetric structural transitions in the cytoplasmic domain with conformational changes in the permeation pathway via an electrostatic network, ultimately controlling channel-gating events. We believe that these results establish a framework for understanding magnesium homeostasis in prokaryotic systems.

PubMed: 41701836
DOI: 10.1073/pnas.2512532123

Experimental method

ELECTRON MICROSCOPY (3.1 Å)