Mapping the DNA-binding response regulators of Desulfovibrio vulgaris Hildenborough

D. vulgaris is a model sulfate reducing bacteria whose genome encodes a high number of two component systems, including 29 DNA-binding response regulators (RRs) whose functions are unknown, but are very likley to be important to the environmental lifestyle of the organism. We determined the gene targets for 24 of these RRs using purified His-tagged RR and sheared genomic DNA in an in vitro DAP-chip (DNA-affinity-purified - chip) assay. For each RR, one target was identified first using gel shift assays, and qPCR was used to ensure that the target was enriched in the RR-bound DNA before the samples were hybridized to a tiling array. Based on the peaks generated by the array analysis, we determined that at least 200 genes are regulated by two component systems in this organism. We also predicted binding site motifs and validated them for 15 RRs using gel shift assays. In vitro DAP-chip for 28 response regulators where RR-bound enriched DNA is compared to input total genomic DNA