FIG. 3.
Genetic organization of the K15 capsule determinant. (A) Regions 1 to 3 of the kpsK15 gene cluster are indicated by different shades of gray. The nonfunctional ORF65 is indicated by a hatched arrow. The locations of two putative integration host factor (IHF) binding sites within the kpsF promoter region and that of the JUMPstart (just upstream of many polysaccharide-associated gene starts) region located upstream of kpsM are indicated, as are the DNA regions whose transcription has been studied by RT-PCR. Fractions of the kpsK15 gene cluster that could be amplified from the corresponding cDNA are marked with plus signs, and those whose transcripts were not detectable are marked with a minus sign. (B) Percent G+C plot of the kpsK15 gene cluster indicative of the segmental structure of this capsule locus representing DNA regions from different sources. The average percent G+C content of the E. coli chromosomal backbone (50.4%) is indicated by a horizontal line.