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Updated: Dec 27, 2025

From Constructs to Crystals – Towards Structure Determination of β-barrel Outer Membrane Proteins
Published on: July 4, 2016
Solution structure of the cytoplasmic domain of NhaP2 a K+/H+ antiporter from Vibrio cholera
George L Orriss1, Vu To1, Aniel Moya-Torres1
1University of Manitoba, Department of Chemistry, 144 Dysart Road, Winnipeg, Manitoba R3T 2N2, Canada.
Abstract:
NhaP2 is a K+/H+ antiporter from Vibrio cholerae which consists of a transmembrane domain and a cytoplasmic domain of approximately 200 amino acids, both of which are required for cholera infectivity. Here we present the solution structure for a 165 amino acid minimal cytoplasmic domain (P2MIN) form of the protein. The structure reveals a compact N-terminal domain which resembles a Regulator of Conductance of K+ channels (RCK) domain connected to a more open C-terminal domain via a flexible 20 amino acid linker. NMR titration experiments showed that the protein binds ATP through its N-terminal domain, which was further supported by waterLOGSY and Saturation Transfer Difference NMR experiments. The two-domain organisation of the protein was confirmed by BIOSAXS, which also revealed that there are no detectable-ATP-induced conformational changes in the protein structure. Finally, in contrast to all known RCK domain structures solved to date, the current work shows that the protein is a monomer.
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