Comparison of Amino Acid Polymerization in B. Subtilis and E. Coli Cell-Free Systems; Hybridization of Their Ribosomes

Much of the information on cell-free protein synthesis in bacterial cells has come from the Escherichia coli system. We felt it would be desirable to use a similar system from other organisms for comparison. For this purpose we chose two organisms, Pseudomnonas fluorescens and Bacillus subtilis. The Pseudomnonas system has already been in use for some time and has been reported upon.' Its study was rewarding; the Pseudornonas supernatant fractions were used mostly with the more stable E. coli ribosomes, and new information on an unstable component of the supernatant was obtained. A cell-free amino acid-incorporating system from B. subtilis has been described by Taubman et al., 2 and more recently by Hirashima et al.3 This present report is largely a comparison of B. subtilis SB-19 with E. coli. Outstanding is the instability of B. subtilis ribosomes, due to a fragility of the 30S subunit. When this subunit was replaced by a 30S particle from E. coli, which readily combines with the 505 of B. subtili8,45 the activity of the hybrids formed was equal to, or sometimes better than the activity of E. coli ribosomes. In the course of this study, mutants of B. subtilis were obtained for comparison. One of Spizizen's6 mutants, 2-34, deficient in gelatinase and protease, was found to yield more stable ribosomes.