ISOLATION AND PURIFICATION OF 2 NOVEL STREPTOMYCETE RNASE INHIBITORS,SAI14 AND SAI20, AND CLONING, SEQUENCING, AND EXPRESSION IN ESCHERICHIA-COLI OF THE GENE CODING FOR SAI14

Two new RNase inhibitors, SaI14 (M-r, similar to 14,000) and SaI20 (M- r, similar to 20,000), were isolated and purified from a Streptomyces aureofaciens strain. The gene sai14, coding for SaI14 protein, was clo ned and expressed in Escherichia coil. The alignment of the deduced am ino acid sequence of SaI14 with that of barstar, the RNase inhibitor f rom Bacillus amyloliquefaciens, showed significant similarity between them, especially in the region which contains most of the residues inv olved in barnase-barstar complex formation.