@article{c0b5b74bfc0246c2b58aa120ceabb9f6,
title = "Inhibition of the alanine tRNA aminoacylation by Ca2+",
abstract = "The effect of Ca2+ concentration on the in vitro aminoacylation of Escherichia coli tRNA's was tested. At a Ca2+ concentration of 0.5 mM the aminoacylation of only two tRNA's, rRNAAla and tRNACys, were found to be inhibited by 56% and 18%, respectively. The aminoacylation of tRNAAla was completely inhibited at 5 mM Ca2+. The relatively high sensitivity of the aminoacylation of tRNAAla to such a low level of Ca2+ might suggest physiological role of Ca2+ in the control of protein synthesis.",
author = "Roy, {Arun K.}",
note = "Funding Information: The mechanism of the cationic inhibition of the tRNA aminoacylation has been explored by various investigators 1{"}3 , however, a clear understanding of the process has not yet emerged. Using the methods of thermal denaturation and optical rotatory dispersion Smith s could not detect any structural change in the tRNA's in the presence of Li ÷ and Na ÷ at a concentration of 0.45 M and higher which partially or completely inactivated their amino acid acceptor capacity. Loftfield and Eigner 2 have suggested that the interaction between the Mg2*-aminoacyladenylate and the tRNA on the enzyme ligase prior to the transfer of the aminoacyl residue to the tRNA involves a transient bridge formation by a {"}dior polyvalent middle weight metal ion similar to cadmium or iron{"}. It is possible that in the case of tRNA Ala Ca ~ ÷ might interfere in the functioning of this metal ion bridge. The relatively low level of Ca 2 ÷-required to specifically inhibit the aminoacylation of the tRNA Ala (56% inhibition at 0.5 mM Ca 2 ÷) suggests the possibility of a regulatory role of Ca 2÷ in protein and RNA synthesis. The preceding speculation is strengthened by the fact that alanine is the most frequently occurring amino acid in E. coli. The observation of Yaniv and Gros 6 in a temperature conditioned mutant ofE. coli where both RNA and protein synthesis at the critical temperature was found to be inhibited due to a modified alanine:tRNA ligase also adds credence to such a possibility. The present finding might also help to explain the low alanyl-, cysteinyl-and prolyl-tRNA ligase activities observed in the enzymes eluted from the hydroxylapatite column 7. Research supported by a faculty research grant from Oakland University and by a National Institutes of Health research grant AM-14744. The initial observation of the effect of Ca: ÷ on the alanine tRNA aminoacylation was made by the author while working in the laboratory of G. Zubay at Columbia University. I thank Professor V.N. Reddy of Oakland University for the use of his amino acid analyzer and valuable criticisms.",
year = "1971",
month = aug,
day = "26",
doi = "10.1016/0005-2787(71)90146-8",
language = "English (US)",
volume = "246",
pages = "349--352",
journal = "BBA Section Nucleic Acids And Protein Synthesis",
issn = "0005-2787",
publisher = "Elsevier BV",
number = "2",
}