High level synthesis in Escherichh coli of the Bacillus subtilis phage ?29 proteins p3 and p4 under the control of phage lambda PL promoter

摘要

The Hind III G fragment from the Bacillus subtilis phage ?29 DNA, inserted downstream from the bacteriophage λ promoter P_L carried by a pBR322 derivative plasmid (pPLc28), directed the synthesis in E. coli of two proteins of apparent molecular weight 27 500 and 12 500. With the use of the recombinants obtained with the DNA from mutants sus3 (91) and sus4 (56), the two proteins were identified as a modified p3 (p3′), the protein covalently linked to the 5′ ends of ?29 DNA, and p4, responsible for the ?29 late transcription, respectively. Under the best conditions used, proteins p4 and p3′ were produced in E. coli from the cloned DNA fragments in an amount corresponding to approximately 30% and 6% of total de novo protein synthesis, respectively.