Cloning and expression of the activity and immunity genes of colicins B and M on ColBM plasmids

✍ Scribed by Ölschläger, Tobias ;Schramm, Edgar ;Braun, Volkmar

• Book ID: 104772454
• Publisher: Springer
• Year: 1984
• Tongue: English
• Weight: 651 KB
• Volume: 196
• Category: Article
• ISSN: 0026-8925
• DOI: 10.1007/bf00436196

✦ Synopsis

The activity and immunity genes for colicins B and M on two conjugative ColBM plasmids, pCl139 and pF166, were cloned into pBR322 and pACYC184, respectively. The colicin regions on both recombinant plasmids were identical with regard to restriction endonuclease sites and the arrangement of the genes. They map close to each other in the order cmi cma cbi cba, where cmi denotes the locus that determines immunity to colicin M, ema the structural gene for colicin M, ebi immunity to colicin B, and cba the structural gene for colicin B. With the use of mutants obtained by insertion of the transposon Tn5, and by translation in minicells, the transcriptional polarity of ema and cba was found to be from right to left. ema and eba code for polypeptides with molecular weights of 27,000 and 58,000, respectively. No evidence of biosynthetic precursors was obtained.