Archaea, a domain of organisms possibly linked to the ancestry of eukarya and bacteria, displays a dichotomic evolutionary pattern. Haloarcula marismortui (H. marismortui), an archaeon discovered in the Dead Sea, has unique traits enabling survival and thriving in hypersaline environments. Research in this study includes investigating the Trk potassium transport system, which may contribute to stability of this archaeon in varying extreme environmental conditions. A primary focus on the TrkE protein role in the system, also known as SapD , which in Haloarcula marismortui is OppD1. The Trk system has been studied in several species, and through each it has been consistently found to be homologous to the E. coli sapABCDF operon, which has been found to encode an ABC transporter. Within this operon in E. coli TrkE is coded for by the SapD gene. The goal of this study was to clone the TrkE homolog from Haloarcula marismortui and continue with further research into the characterization of the protein to aid in the prediction of its overall function in potassium transport. Data in this study strongly suggest the size of the H. marismortui homolog of TrkE, OppD1, is larger than its E.coli homolog by approximately 10,000 Daltons. Further analysis also identified that the mainly alpha-helical protein has a significant sequence identity with SapD. Future considerations include looking at the purpose of the N-terminal extended region of OppD1 not seen in SapD, and further analyzing OppD1 for structure changes in varying salt conditions and possible binding partners. The exceptional survival skills of H. marismortui in high-salinity environments, possibly facilitated by the Trk system, make it an excellent model for studying halophiles. These insights offer valuable understanding into how halophiles maintain cellular integrity under harsh conditions, especially regarding OppD1's potential role within the Trk system for ion transport and osmotic regulation in different environmental settings.
