Kleinman Claudia L, Sycz Gabriela, Bonomi Hernán R, Rodríguez Romina M, Zorreguieta Angeles, Sieira Rodrigo
Lady Davis Institute, McGill University, Montreal, QC H3T 1E2, Canada.
Fundación Instituto Leloir, Ciudad de Buenos Aires C1405BWE, Argentina.
Nucleic Acids Res. 2017 Jun 2;45(10):5757-5769. doi: 10.1093/nar/gkx165.
LuxR-type transcription factors control diverse physiological functions necessary for bacterial adaptation to environmental changes. In the intracellular pathogen Brucella, the LuxR homolog VjbR has been shown to regulate the expression of virulence factors acting at early stages of the intracellular infection and, directly or indirectly, hundreds of additional genes. However, the precise determination of VjbR direct targets has so far proved elusive. Here, we performed chromatin immunoprecipitation of VjbR followed by next-generation sequencing (ChIP-seq). We detected a large amount of VjbR-binding sites distributed across the Brucella genome and determined a markedly asymmetric binding consensus motif, an unusual feature among LuxR-type regulators. RNA-seq analysis performed under conditions mimicking the eukaryotic intracellular environment revealed that, among all loci associated to VjbR-binding, this regulator directly modulated the expression of only a subset of genes encoding functions consistent with an intracellular adaptation strategy for survival during the initial stages of the host cell infection. Other VjbR-binding events, however, showed to be dissociated from transcription and may require different environmental signals to produce a transcriptional output. Taken together, our results bring new insights into the extent and functionality of LuxR-type-related transcriptional networks.
LuxR 型转录因子控制着细菌适应环境变化所需的多种生理功能。在细胞内病原体布鲁氏菌中，LuxR 同源物 VjbR 已被证明可调节在细胞内感染早期起作用的毒力因子的表达，以及直接或间接调节数百个其他基因。然而，迄今为止，精确确定 VjbR 的直接靶标一直难以实现。在此，我们进行了 VjbR 的染色质免疫沉淀，随后进行了下一代测序（ChIP-seq）。我们检测到大量分布在布鲁氏菌基因组中的 VjbR 结合位点，并确定了一个明显不对称的结合共有基序，这是 LuxR 型调节因子中的一个不寻常特征。在模拟真核细胞内环境的条件下进行的 RNA-seq 分析表明，在与 VjbR 结合相关的所有基因座中，该调节因子仅直接调节了一部分基因的表达，这些基因编码的功能与宿主细胞感染初始阶段生存的细胞内适应策略一致。然而，其他 VjbR 结合事件显示与转录无关，可能需要不同的环境信号才能产生转录输出。综上所述，我们的结果为 LuxR 型相关转录网络的范围和功能带来了新的见解。
