Effects of divalent cations on the splicing of phage T4 thymidylate synthase intron RNA

Abstract

Effects of divalent cations such as Mg²⁺, Mn²⁺, Ca²⁺, and Zn² on splicing activity of phage T4 thymidylate synthase intron RNA have been investigated. At the concentration of 0.5 mM Mn²⁺ in the absence of Mg²⁺, a very small amount of pre‐RNA was cleaved into ligation products (E1‐E2) but no circular or linear intron was produced. As the concentration of Mn²⁺ was increased from 1 to 5 mM. the pre‐RNA was completely hydrolyzed. In the presence of 5 mM Mg²⁺, both the linear intron and circular intron were produced but no E1‐E2 ligation product was produced. At both 3 and 5 mM Mn²⁺, the RNA was hydrolyzed completely as observed with no Mg²⁺ being present. In the case of Zn²⁺, even at 0.5 mM concentration, the pre‐RNA was completely hydrolyzed. This observation suggested that Zn²⁺ facilitates RNA hydrolysis more rapidly than Mn²⁺ does. At 5mM Ca²⁺, the RNA was not hydrolyzed and remained intact as a primary transcript.

Key words:

• Divalent cation
• T4 phage
• Thymidylate synthase intron

Notes

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