A ribosome-independent, soluble stringent factor-like enzyme isolated from a Bacillus brevis.

A ribosome-independent synthesis of guanosine 5',3'-polyphosphates has been found in the soluble fraction of Bacillus brevis (ATCC 8185) extracts. The partially purified enzyme catalyzes the formation of both guanosine 5'-diphosphate 3'-diphosphate and guanosine 5'-triphosphate 3'-diphosphate, does not require 20% methanol to stimulate the rate of reaction, and is not stimulated by complexing with ribosomes of either Escherichia coli or B. brevis. The B. brevis enzyme system is not inhibited by RNase A or thiostrepton, and is only slightly inhibited by tetracycline. The pyrophosphoryl donor specificity of the B. brevis enzyme is similar to that of the E. coli ribosome-stringent factor system.