Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, USA.
Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, USA
J Bacteriol. 2020 Mar 11;202(7). doi: 10.1128/JB.00777-19.
is a bacterial symbiont that colonizes the light organ of the Hawaiian bobtail squid, Certain strains of express a type VI secretion system (T6SS), which delivers effectors into neighboring cells that result in their death. Strains that are susceptible to the T6SS fail to establish symbiosis with a T6SS-positive strain within the same location of the squid light organ, which is a phenomenon termed strain incompatibility. This study investigates the regulation of the T6SS in strain FQ-A001. Here, we report that the expression of Hcp, a necessary structural component of the T6SS, depends on the alternative sigma factor σ and the bacterial enhancer binding protein VasH. VasH is necessary for FQ-A001 to kill other strains, suggesting that VasH-dependent regulation is essential for the T6SS of to affect intercellular interactions. In addition, this study demonstrates VasH-dependent transcription of within host-associated populations of FQ-A001, suggesting that the T6SS is expressed within the host environment. Together, these findings establish a model for transcriptional control of in within the squid light organ, thereby increasing understanding of how the T6SS is regulated during symbiosis. Animals harbor bacterial symbionts with specific traits that promote host fitness. Mechanisms that facilitate intercellular interactions among bacterial symbionts impact which bacterial lineages ultimately establish symbiosis with the host. How these mechanisms are regulated is poorly characterized in nonhuman bacterial symbionts. This study establishes a model for the transcriptional regulation of a contact-dependent killing machine, thereby increasing understanding of mechanisms by which different strains compete while establishing symbiosis.
是一种定植在夏威夷短尾乌贼光感器官的细菌共生体。某些 菌株表达一种 VI 型分泌系统（T6SS），该系统将效应物输送到邻近的细胞中，导致其死亡。易受 T6SS 影响的菌株无法与同一位置的 T6SS 阳性菌株建立共生关系，这种现象称为菌株不相容性。本研究调查了 FQ-A001 菌株中 T6SS 的调控。在这里，我们报告说 Hcp 的表达，T6SS 的必要结构成分，依赖于替代 sigma 因子 σ 和细菌增强子结合蛋白 VasH。VasH 是 FQ-A001 杀死其他菌株所必需的，这表明 VasH 依赖性调节对于 菌株 T6SS 影响细胞间相互作用是必不可少的。此外，本研究还证明了 VasH 依赖性转录在 FQ-A001 的宿主相关群体中，这表明 T6SS 在宿主环境中表达。综上所述，这些发现建立了一个模型，用于在鱿鱼光器官中调节 菌株中的 T6SS，从而增加了对共生期间 T6SS 如何调节的理解。动物携带具有特定特征的细菌共生体，这些特征有助于宿主的适应性。促进细菌共生体之间细胞间相互作用的机制会影响哪些细菌谱系最终与宿主建立共生关系。这些机制是如何被调控的在非人类细菌共生体中描述得很差。本研究建立了一个接触依赖性杀伤机器的转录调控模型，从而增加了对不同菌株在建立共生关系时竞争机制的理解。
