ccdB cassette used for pCoofy vectors. (A) The Llp5 variant of the strong E.coli major outer membrane lipoprotein promoter was introduced upstream of the coding sequence to drive constitutive ccdB transcription. -35 and -10 regulatory sequences are highlighted. A Shine-Dalgarno sequence was also added to ensure ccdB translation. The original start codon was converted to ATT (Ile, indicated in bold) for technical reasons. (B) The ccdB cassette was delivered by Sloning in pPCRSript (sequence available on request) and tested for toxicity by transformation into sensitive E.coli cells.