Construction of the CDS5 knock-out vector and insertion of the lacZ cassette.

A. The regions between plasmid CDS4-CDS6 are shown, which highlight differences between the three plasmid constructs listed. In pCDS5KO, the ∼600 bp PacI-BsaBI fragment in pGFP::SW2 was replaced with a 35 bp oligo (including a unique StuI site for further cloning), resulting the deletion of CDS5. In placZ-CDS5KO, a lacZ cassette was inserted into the StuI site of pCDS5KO. This lacZ cassette contains a ∼200 bp promoter from chlamydiaphage Chp2 ORF5 (Chp2P5) placed in front of a 3.6 kb HindIII-PsiI lacZ fragment from pSV-B-Gal (Promega). The drawings are not to scale. B. Map showing the features of plasmid pCDS5KO. The inner circle represents the plasmid pSW2 from C. trachomatis SW2 (black) and the non-chlamydial sequences (red). The circle is graduated with 1 kb scale bars. The location of CDS 4 and CDS 6 are marked and the deletion of CDS5 is represented by the scissors symbol.