Quorum sensing (QS) is a cell-to-cell communication process that enables bacteria to coordinate group behaviors. In Vibrio cholerae colonies, a program of spatial-temporal cell death is among the QS-controlled traits. Cell death occurs in two phases, first along the colony rim, and subsequently, at the colony center. Both cell death phases are driven by the type 6 secretion system (T6SS). Here, we show that HapR, the master QS regulator, does not control t6ss gene expression nor T6SS-mediated killing activity. Nonetheless, a Δ hapR strain displays no cell death at the colony rim. RNA-Sequencing (RNA-Seq) analyses reveal that HapR activates expression of an operon containing four genes of unknown function, vca0646-0649. Epistasis and overexpression studies show that two of the genes, vca0646 and vca0647 , are required to drive cell death in both a Δ hapR and a Δ hapR Δ t6ss strain. Thus, vca0646 - 0649 are regulated by HapR but act independently of the T6SS machinery to cause cell death, suggesting that a second, parallel pathway to cell death exists in V. cholerae .

中文翻译：

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群体感应通过 6 型分泌依赖性和非依赖性机制在霍乱弧菌中编排平行细胞死亡通路


群体感应 （QS） 是一种细胞间通信过程，使细菌能够协调群体行为。在霍乱弧菌菌落中，时空细胞死亡程序是 QS控制的性状之一。细胞死亡分为两个阶段，首先沿着集落边缘，然后是在集落中心。两个细胞死亡阶段都由 6 型分泌系统 （T6SS） 驱动。在这里，我们表明 HapR 是主要的 QS 调节因子，不控制 t6ss 基因表达，也不控制 T6SS 介导的杀伤活性。尽管如此，Δ hapR 菌株在集落边缘没有显示细胞死亡。RNA 测序 （RNA-Seq） 分析显示，HapR 激活包含四个功能未知基因的操纵子 vca0646-0649 的表达。上位性和过表达研究表明，在 Δ hapR 和 Δ hapR Δ t6ss 菌株中，两个基因 vca0646 和 vca0647 是驱动细胞死亡所必需的。因此，vca0646 - 0649 受 HapR 调节，但独立于 T6SS 机制起作用，导致细胞死亡，这表明霍乱弧菌中存在细胞死亡的第二种平行途径。