The crossing of two unwound transmembrane regions that is the hallmark of the NhaA structural fold is critical for antiporter activity.

ABSTRACT: Cell pH and Na⁺ homeostasis requires Na⁺/H⁺ antiporters. The crystal structure of NhaA, the main Escherichia coli Na⁺/H⁺ antiporter, revealed a unique NhaA structural fold shared by prokaryotic and eukaryotic membrane proteins. Out of the 12 NhaA transmembrane segments (TMs), TMs III-V and X-XII are topologically inverted repeats with unwound TMs IV and XI forming the X shape characterizing the NhaA fold. We show that intramolecular cross-linking under oxidizing conditions of a NhaA mutant with two Cys replacements across the crossing (D133C-T340C) inhibits antiporter activity and impairs NhaA-dependent cell growth in high-salts. The affinity purified D133C-T340C protein binds Li⁺ (the Na⁺ surrogate substrate of N

SUBMITTER: Rimon A 

PROVIDER: S-EPMC10928194 | biostudies-literature | 2024 Mar

REPOSITORIES: biostudies-literature