Fig. 2.

Effect of manganese on the expression of Irr-regulated genes and promoter occupancy by Irr. (A–C). mRNA transcripts of bll4920, blr3555, and blr6519 obtained from cells grown under different metal conditions were analyzed by qPCR. The data are expressed as the relative starting quantity (SQ) of the respective mRNAs normalized to the housekeeping gene gapA, and presented as the average of three replicates ± the standard deviation. (D–F) Cross-linking of parent strain cells grown under different conditions of iron and manganese, followed by co-IP using anti-Irr antiserum was carried out as described in Materials and Methods. The mock experiment was carried out without antibody. Immunoprecipitated DNA was analyzed by qPCR using primers delimiting the promoter regions of the respective genes. The data are expressed as the relative SQ of the respective pull-down DNA normalized to the mock pull-down samples and presented as the average of three replicates ± the standard deviation. The normalized SQ values obtained were considered to be directly proportional to the Irr promoter occupancy of the respective genes.