K+ and Mg2+ ions promote the self-splicing of the td intron RNA inhibited by spectinomycin

In Kook Park, Jung Suk Sung

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7 Scopus citations

Abstract

The effects of Mg2+ and K+ ions on the self-splicing inhibition of the td (thymidylate synthase gene) intron RNA by spectinomycin were investigated. The maximum splicing activity occurred at 20 mM KCl. The K(m) and V(max) values for GTP in the presence of 5 mM Mg2+ are 2.25 μM and 0.55 min-1, whereas those for GTP both in the presence of 5 mM Mg2+ and 5 mM K+ are 1.23 μM and 0.46 min-1, respectively. Spectinomycin at 10 mM concentration inhibited the splicing by about 10%, but at 20 mM concentration, the splicing rate was inhibited by about 63%. The splicing inhibition by the low concentration of spectinomycin was overcome markedly as the concentration of Mg2+ ion was raised. At 30 mM spectinomycin, however, the splicing inhibition was not significantly affected by increasing the concentration of Mg2+. A similar activation of the splicing rate was observed as the concentration of K+ ion was increased. The concentration of K+ ion required for the normal recovery of the splicing was much higher than that of Mg2+ ion. Unlike Mg2+ ion, 30 mM K+ ion effectively alleviated the splicing inhibition by spectinomycin at its high concentration. The results indicate that K+ and Mg2+ ions may show mechanistically different interactions with spectinomycin in the self-splicing reaction of the td intron RNA. Copyright (C) 2000 Elsevier Science B.V.

Original languageEnglish
Pages (from-to)94-99
Number of pages6
JournalBiochimica et Biophysica Acta - Gene Structure and Expression
Volume1492
Issue number1
DOIs
StatePublished - 21 Jun 2000

Keywords

  • K
  • Mgion
  • Spectinomycin
  • T4 phage
  • td intron RNA

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