Figure 6

Co-expression profile of operons: the schematic model of the operon diversity and its examples. (A) Schematic model of a diverse operon. In this model, we assume that there is a longer TU and a shorter TU. Arrows indicate the region transcribed as a TU. Open boxes to the side and above the grid indicate genes. Each box in the grid indicates the level of correlation of gene expression as colors from blue to red correspond to the correlation coefficients. The gene pairs without the TU boundary should show strong correlation with vivid red color. On the other hand, gene pairs across the boundary should show a slightly weaker correlation with orange color. (B) The sig B operon. There are two promoters in the sig B operon. The first one is located in the upstream of the first gene of the operon, and second one is located in between fourth and fifth genes. Therefore, two different transcripts cause this pattern. (rsb V in this operon was not measured in the microarray experiments, so the region of this gene is not colored.) (C) The clp C operon. The transcription of this operon is basically promoted by sigma B, while the last two genes (sms and yac K) were reported to be also transcribed by sigma M.