Mashruwala Ameya A, Bassler Bonnie L
Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544, USA.
The Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA.
bioRxiv. 2024 Sep 23:2024.09.23.614608. doi: 10.1101/2024.09.23.614608.
Quorum sensing (QS) is a cell-to-cell communication process that enables bacteria to coordinate group behaviors. In 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 VI secretion system (T6SS). Here, we show that HapR, the master QS regulator, does not control gene expression nor T6SS-mediated killing activity. Nonetheless, a Δ strain displays no cell death at the colony rim. RNA-Seq analyses reveal that HapR activates expression of an operon containing four genes of unknown function, Epistasis and overexpression studies show that two of the genes, and , are required to drive cell death in both a Δ and a Δ Δ strain. Thus, - 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 .
群体感应（QS）是一种细胞间通讯过程，它使细菌能够协调群体行为。在菌落中，时空细胞死亡程序是QS控制的性状之一。细胞死亡分两个阶段发生，首先沿着菌落边缘，随后在菌落中心。两个细胞死亡阶段均由VI型分泌系统（T6SS）驱动。在此，我们表明，QS的主要调节因子HapR既不控制基因表达，也不控制T6SS介导的杀伤活性。尽管如此，一个Δ菌株在菌落边缘未显示细胞死亡。RNA测序分析表明，HapR激活了一个包含四个功能未知基因的操纵子的表达，上位性和过表达研究表明，其中两个基因， 和 ，是在Δ和ΔΔ菌株中驱动细胞死亡所必需的。因此， - 受HapR调控，但独立于T6SS机制发挥作用以导致细胞死亡，这表明 在细胞死亡中存在第二条平行途径。
