Mg2+ Enhances the Formation of 2′,3′-cGMP, an Intermediate of RNA Cleavage by Binase

Binase, the ribonuclease secreted by Bacillus pumilus, is an endonuclease that cleaves the phosphodiester bond between the 3′-guanyl residue and 5′-OH residue of an adjacent nucleotide, with the formation of a corresponding intermediate, 2′,3′-cGMP on the first stage of a catalytic reaction. Binase possesses selective antitumor effect and induces apoptosis of lung carcinoma A549 cells. It was shown that the 2′,3′-cGMP messenger could exist in the reaction mixture over an hour. Furthermore, the addition of divalent non-transition metal Mg2+ increases the level of 2′,3′-cGMP formed by binase and that could be associated with the stabilization of RNA tertiary structure by this metal. It has been shown that exogenous 2′,3′-cGMP does not induce apoptosis of A549 cells, which are sensitive to binase. However, taking into account the cell-penetrating ability of binase, it can be concluded that 2′,3′-cGMP contributes to apoptogenic binase action only when it is formed intracellularly. © 2016, Springer Science+Business Media New York.