ChIP-seq analysis of Brucella reveals transcriptional regulation of GntR

Transcriptional regulator GntR controls diverse physiological functions necessary for Brucella survival. In the intracellular pathogen Brucella, GntR has been shown to regulate the expression of genes related to virulence. However, the precise determination of GntR direct targets has so far proved elusive. Therefore, we performed chromatin immunoprecipitation of GntR10 followed by next-generation sequencing (ChIP-seq). We selected target gene BAB1_1163 directly regulated by GntR10 and created the mutant (2308Δ1163) from virulent Brucella abortus 2308 (S2308). 2308Δ1163 strain survival capability in murine macrophages (RAW 264.7) was detected and the levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were also measured. We detected 88 intergenic ChIP-seq peaks of GntR10 binding distributed across the Brucella genome and determined a markedly asymmetric binding consensus motif with 12 bp length. 2308Δ1163 showed reduced survival capability in RAW 264.7. After the macrophages were infected with 2308Δ1163, the levels of TNF-α and IL-1β were decreased and were significantly lower than that for the S2308-infected group, indicating that the 2308Δ1163 mutant could inhibit the secretion of inflammatory cytokines. Taken together, the research has recorded valuable data about GntR10 and provided new insights into the functionality of GntR10.