REGULATION OF THE BIOSYNTHESIS OF EXTRACELLULAR RIBONUCLEASES IN THEIR NATIVE STRAINS OF BACILLI AND RECOMBINANT STRAINS OF ESCHERICHIA-COLI

Regulation of the biosynthesis of extracellular ribonucleases of Bacil lus amyloliquefaciens H2 (barnase), Bacillus intermedius 7P (binase), and Bacillus pumilus KMM 62 (RNase Bp) was studied in their native str ains and recombinant Escherichia coli strains. Recombinant plasmids we re obtained that contained genes encoding barnase, binase, and RNase B p under the control of their own regulatory sequences (plasmids pMT415 , pML5, and pML61), genes encoding barnase and binase under the contro l of the tac promoter and the phoA leader sequence (plasmids pMT416 an d pML163), and the binase-encoding gene under the control of the regul atory sequences of the barnase and RNase Bp genes (plasmids pML53 and pML67, respectively). Inorganic phosphate (P-i) inhibited the biosynth esis of binase and RNase Bp in natural strains B. intermedius 7P and B . pumilus KMM 62 and recombinant E. coli strains when genes encoding t hese RNases were under the control of their own regulatory sequences. In contrast, the biosynthesis of barnase - either in the natural B. am yloliquefaciens strain or in recombinant E. coli strains - was not aff ected by P-i. Neither did inorganic phosphate produce any effect on th e biosynthesis of binase when the binase-encoding gene was under the c ontrol of the barnase gene promoter (pML53). The leader sequences and promoters were found to be similar in the binase and RNase Bp genes an d differed considerably from the leader sequence and promoter of the b arnase gene. The promoter regions of the binase and RNase Bp genes, bu t not of the barnase gene, contained sequences that resembled the Pho box of the phosphate regulon from E. coli.