Functional characterization of NhaP-type Na⁺/H⁺ antiporter and its expression in plant

Abstract

Synechocystis sp. PCC 6803 contains five putative Na⁺/H⁺ antiporters, two NhaP type and three NapA type antiporters. A NhaP antiporter from Synechocystis sp. PCC 6803 (SynNhaP1) catalyzes the exchange between Na⁺ and H⁺ as well as Li⁺ and H⁺ whereas a NhaP from halotolerant cyanobacterium Aphanothece halophytica (ApNhaP) catalyzes the exchange between Na⁺ and H⁺ as well as Ca²⁺ and H⁺. Here, we examined the role of C-terminal tail of SynNhaP1. We constructed various C-terminal deletion mutants and studied their functional properties. It was found that C-terminal is important for the exchange activity and its pH dependence. We also constructed the transgenic Arabidopsis and tobacco plants using SynNhaP1 with the root specific promoter. Their localization in plants and salt stress tolerance were examined. These results will be presented.