Figure 4.

Transcript abundance and degradation of the dcw gene cluster. The dcw gene cluster contains 16 ORFs involved in cell envelope biosynthesis and cell division. Several promoters have been described (see Fig. 3), and it is likely that they are all used, to varying extents. It has also been speculated that the cluster may sometimes be transcribed in its entirety. The ORFs were plotted here in the order they are transcribed, showing their array signal intensities (average differences) throughout the timecourse. Although average difference is only an approximate indicator of transcript abundance, relatively high levels of steady-state RNA are observed downstream of the mraZ and ddlB promoters, at the 5′ end and about two-thirds of the way into the transcript, respectively. The middle portion of the operon has lower steady-state RNA levels and is degraded more slowly (see Fig. 3).