Transcriptional organization of the sycO-ypkA-yopJ operon. Arrows represent the length and direction of transcription of sycO, ypkA and yopJ on pCD1. The horizontal arrow depicts the putative primary RNA transcript. The arrowheads indicate the location of primer pair and the expected amplicons. Genomic DNA and cDNA generated by RT were used as the templates for PCR and RT-PCR, respectively. To ensure that there was no contamination of genomic DNA in the RT reactions, negative controls of RT-PCR were performed using 'cDNA' generated without reverse transcriptase as templates. Reactions containing primer pairs without template were also included as blank controls. As expected, both negative and blank controls of RT-PCR gave no amplicon (data not shown).