E Podoliak, G H U Lamm, E Marin, A V Schellbach, D A Fedotov, A Stetsenko, M Asido, N Maliar, G Bourenkov, T Balandin, C Baeken, R Astashkin, T R Schneider, A Bateman, J Wachtveitl, I Schapiro, V Busskamp, A Guskov, V Gordeliy, A Alekseev, K Kovalev
Light-driven sodium pumps (NaRs) are unique ion-transporting microbial rhodopsins. The major group of NaRs is characterized by an NDQ motif and has two aspartic acid residues in the central region essential for sodium transport. Here we identify a subgroup of the NDQ rhodopsins bearing an additional glutamic acid residue in the close vicinity to the retinal Schiff base. We thoroughly characterize a member of this subgroup, namely the protein ErNaR from Erythrobacter sp. HL-111 and show that the additional glutamic acid results in almost complete loss of pH sensitivity for sodium-pumping activity, which is in contrast to previously studied NaRs...
April 10, 2024: Nature Communications