Some organisms from the domain Archaea, called extremophiles, thrive in geochemically extreme conditions that would be detrimental to most life on Earth. This domain includes the halophiles, salt loving organisms, which require a minimum of 0.2M salt concentration for survival. Cysteinyl t-RNA synthetase, CysRS, catalyzes the attachment of cysteine to its cognate tRNA and is an example of a highly conserved protein with well characterized halophilic adaptations. Using the Halobacterium salinarum CysRS, we are investigating how the protein interacts with group I metals, which seem to maintain its structure and stability. The effects and binding of the metals on the protein were investigated through equilibrium dialysis and atomic absorption spectroscopy (AAS). The goal of using equilibrium dialysis was to determine the rate of diffusion over time and compare and contrast the results between halophilic CysRS and E.coli CysRS, a negative control. It was observed that the halophilic protein binds faster to the cations than the E. coli protein. This was reflected by the increase in metal concentration inside the dialysis bag. By characterizing this interaction, we can calculate the binding constant of the protein, Kd, to the metal and establish some rules about how metals interact with proteins and certain amino acids. The metal binding affinity of the protein can also be applied to techniques used in environmental and industrial remediation that could help us clean up metal contaminated sites, and/or recover metals from the environment.

Metal binding affinity of Halobacterium salinarum cysteinyl-tRNA synthetase

255th National Meeting (2018)

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