Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK.
Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK.
Cell Rep. 2018 Jan 16;22(3):774-785. doi: 10.1016/j.celrep.2017.12.075.
Incorporation of disulfide bonds into proteins can be critical for function or stability. In bacterial cells, the periplasmic enzyme DsbA is responsible for disulfide incorporation into many extra-cytoplasmic proteins. The type VI secretion system (T6SS) is a widely occurring nanomachine that delivers toxic effector proteins directly into rival bacterial cells, playing a key role in inter-bacterial competition. We report that two redundant DsbA proteins are required for virulence and for proper deployment of the T6SS in the opportunistic pathogen Serratia marcescens, with several T6SS components being subject to the action of DsbA in secreting cells. Importantly, we demonstrate that DsbA also plays a critical role in recipient target cells, being required for the toxicity of certain incoming effector proteins. Thus we reveal that target cell functions can be hijacked by T6SS effectors for effector activation, adding a further level of complexity to the T6SS-mediated inter-bacterial interactions which define varied microbial communities.
二硫键的形成对于蛋白质的功能或稳定性至关重要。在细菌细胞中，周质酶 DsbA 负责将二硫键掺入许多细胞外蛋白中。 类型 VI 分泌系统（T6SS）是一种广泛存在的纳米机器，可将毒性效应蛋白直接递送至竞争细菌细胞，在细菌间竞争中发挥关键作用。我们报告说，两种冗余的 DsbA 蛋白对于机会性病原体粘质沙雷氏菌的毒力和 T6SS 的正确部署是必需的，几个 T6SS 成分在分泌细胞中受到 DsbA 的作用。重要的是，我们证明 DsbA 也在靶细胞中发挥关键作用，对于某些进入的效应蛋白的毒性是必需的。因此，我们揭示了靶细胞功能可以被 T6SS 效应蛋白劫持用于效应子激活，这为 T6SS 介导的细菌间相互作用增加了一个复杂性，这些相互作用定义了多样化的微生物群落。
