Energy Charge and Protein Synthesis

The histidyl transfer RNA synthetase of Salmonella typhimurium LT-2 is inhibited by ADP and AMP, and consequently is responsive to energy charge. The arginyl-, valyl-, and lysyl-tRNA synthetases from Salmonella are also inhibited by ADP and AMP. Reduced inhibition of a mutant histidyl-tRNA synthetase adds support to the idea that the greater inhibition of the wild type enzyme is not fortuitous, but is maintained to serve a physiological function. By affecting the activity of the various aminoacyl-tRNA synthetases, energy charge could regulate the site of the charged tRNA pool and thus control the rate of protein synthesis.