Mostly Dead, Slightly Alive: Glimpses into the Proteomes of Dead Sea Halophilic Archaea

Author: Richard Baker-Strader

Faculty Supervisor: Jason Cantley

Department: Biology

The Dead Sea is a landlocked lake in the Levant that once marked the southern tip of a Pliocene Mediterranean lagoon. Geological shifts during the Pleistocene, followed by Holocene drying, have since severed the connection to the sea and concentrated the remaining solutes. The resulting supersaturated brine exerts such intense osmotic pressure that the waters are almost universally hostile to life. Today, only extremophilic archaea are sufficiently adapted to survive in small numbers, lying nearly dormant until rare floods dilute surface brines and allow proliferation. Continued evaporation and falling water levels force massive precipitation of halite from solution. This is shifting the Dead Sea to a magnesium-dominated chemical regime, increasing osmotic pressures beyond what is typical of seawater brines. Archaea remaining in the water column must thus produce extremely hydrophilic proteins and an arsenal of ion transporters to maintain sufficient cytoplasmic hydration levels for cellular function. This project will leverage publicly available genomes and compare genes encoding ion transporters in two Dead Sea archaea, Halorubrum sodomense and Halobaculum gomorrense, with less extremophilic relatives. From this data, it will be possible to identify the relative abundance and types of ion transport proteins enabling survival in this harsh environment.