Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

In vivo and in vitro effects of methylmercury on the activities of aminoacyl-tRNA synthetases in rat brain

  • 27 Accesses

  • 7 Citations

Abstract

The activities of six aminoacyl-tRNA synthetase species were determined using enzyme preparations partially purified from the brains of control and methylmercury (MeHg)-treated rats. The activities of Asp-, Leu- and Tyr-tRNA synthetases were significantly reduced in the brains of MeHg-intoxicated rats, whereas those of Lysand Met-tRNA synthetases remained unchanged. In contrast, the activity of His-tRNA synthetase was significantly increased in the symptomatic phase of MeHg intoxication. The activities of these six aminoacyl-tRNA synthetases in the control brains were affected to different extents on the direct addition of MeHg to the assay system in vitro. No positive correlation was observed between the in vivo and in vitro effects of MeHg on the enzyme activities. These results indicate that the aminoacylation of tRNA is one of the actions of MeHg, which leads to inhibition of protein synthesis, and it is suggested that the syntheses of cellular proteins may be modified in different ways by MeHg, depending on their amino acid compositions.

This is a preview of subscription content, log in to check access.

References

  1. Bollum FJ (1968) Filter disk techniques for assaying radioactive macromolecules. In: Grossman L, Moldave K (eds) Methods in enzymology, Vol. 12 Part B. Academic Press, New York, pp 169–173

  2. Cheung M, Verity MA (1985) Experimental methylmercury neurotoxicity: locus of mercurial inhibition of brain protein synthesis in vivo and in vitro. J Neurochem 44: 1799–1808

  3. Dang CV, Dang CV (1986) Multienzyme complex of aminoacyl-tRNA synthetase: an essence of being eukaryotic. Biochem J 239: 249–255

  4. Jacobs JM, Carmichael N, Cavanagh JB (1977) Ultrastructural changes in the nervous system of rabbits poisoned with methylmercury. Toxicol Appl Pharmacol 39: 249–261

  5. Kawamata O, Kasama H, Omata S, Sugano H (1987) Decrease in protein phosphorylation in central and peripheral nervous tissues of methylmercury-treated rat. Arch Toxicol 59: 346–352

  6. Lowry OH, Rosebrough NJ, Farr AL, Randall RJ (1951) Protein measurement with the Folin phenol reagent. J Biol Chem 193: 265–275

  7. Mehler AH, Chakraburtty K (1971) Some questions about the structure and activity of aminoacyl-tRNA synthetase. Adv Enzymol 35: 443–501

  8. Miura K, Imura N (1987) Mechanism of methylmercury cytotoxicity. CRC Crit Rev Toxicol 18: 215–243

  9. Murayama A, Raffin JP, Remy P, Ebel JP (1975) Yeast phenylalanyl-tRNA synthetase: properties of the sulfhydryl groups; evidence for SH requirement in tRNA acylation. FEBS Lett 53: 15–22

  10. Nishimura S (1971) Fractionation of tRNA by DEAE-Sephadex A-50 column chromatography. In: Cantoni GL, Davies DR (eds) Procedures in Nucleic Acid Research, Vol. 2. Harper and Row, pp 5452–5564

  11. Omata S, Sugano H (1985) Methylmercury: effects on protein synthesis in nervous tissue. In: Blum K, Manzo L (eds) Neurotoxicology. Marcel Dekker Inc., New York, pp 369–383

  12. Omata S, Sugano H (1986) Biochemical studies on methylmercury poisoning in nervous tissues. In: Tsubaki T, Takahashi H (eds) Recent advances in minamata disease studies. Kodansha Ltd, Tokyo, pp 150–169

  13. Omata S, Sakimura K, Tsubaki H, Sugano S (1978) In vivo effect of methylmercury on protein synthesis in brain and liver of the rat. Toxicol Appl Pharmacol 44: 367–378

  14. Omata S, Horigome T, Momose Y, Kambayashi M, Mochizuki M, Sugano H (1980) Effect of methylmercury chloride on the in vivo rate of protein synthesis in the brain of the rat: examination with the injection of a large quantitiy of 14C-valine. Toxicol Appl Pharmacol 56: 207–215

  15. Omata S, Momose Y, Ueki H, Sugano H (1982) In vivo effect of methylmercury on protein synthesis in peripheral nervous tissues of the rat. Arch Toxicol 49: 203–214

  16. Omata S, Kasama H, Hasegawa H, Hasegawa K, Ozaki K, Sugano H (1986) Species difference between rat and hamster in tissue accumulation of mercury after administration of methylmercury. Arch Toxicol 59: 249–254

  17. Som K, Hardesty B (1975) Isolation and partial characterization of an aminoacyl-tRNA synthetase complex from rabbit reticulocytes. Arch Biochem Biophys 166: 507–517

  18. Yip RK, Chang LW (1981) Vulnerability of dorsal root neurons and fibers toward methylmercury toxicity; a morphological evaluation. Environ Res 26: 1152–1167

Download references

Author information

Correspondence to Saburo Omata.

Additional information

This work was supported in part by a grant from the Japanese Environmental Agency.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Hasegawa, K., Omata, S. & Sugano, H. In vivo and in vitro effects of methylmercury on the activities of aminoacyl-tRNA synthetases in rat brain. Arch Toxicol 62, 470–472 (1988). https://doi.org/10.1007/BF00288352

Download citation

Key words

  • Methylmercury
  • Aminoacyl tRNA synthetase
  • Brain
  • Protein synthesis
  • Rat