Effect of purine and pyrimidine limitations on RNA synthesis in Bacillus subtilis

The effects of varying the intracellular levels of GTP or UTP on the rate of RNA synthesis in Bacillus subtilis were studied. The levels of these nucleotides were manipulated by pyrimidine limitation in a pyr auxotroph, by purine limitation in a pur auxotroph, or by the addition of decoyinine , which specifically inhibits GMP synthesis. Decreased levels of UTP and GTP were accompanied by dramatically decreased synthesis and accumulation of stable RNAs (tRNA and rRNA), but mRNA synthesis was less affected. However, sporulation was initiated only when the intracellular level of GTP decreased.