Association of Fis with promoter regions of nrfA, sdhC, dmsA, nirB, and rrsA in mid-log growth phase under aerobic growth conditions. Relative occupancy on Y-axis represents the ratio of the immunoprecipitated DNA with and without antibodies using quantitative PCR. (A) In mid-log growth phase, Fis is present at the promoter region of nrfA, while the RNAP β levels remain at background levels. (B,C) Fis ChIP shows high occupancies at the promoter regions of nirB and rrsA. Owing to the transcriptional repression of the nirB gene under the conditions, RNAP β levels remain at background levels across the gene. However, rrsA is highly expressed in rapidly growing cells, so the RNAP β occupancy plateaus at the high level across the gene. (D) Fis is not associated with the promoter regions of sdhC and dmsA. RNAP β levels are high at the promoter and ORF regions of sdhC but are not present at the promoter regions of dmsA.
