National Heart and Lung Institute, Imperial College London, London, UK.
Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Sevilla 41012, Spain.
Microbiology (Reading). 2023 Jul;169(7). doi: 10.1099/mic.0.001367.
The life of bacteria is challenging, to endure bacteria employ a range of mechanisms to optimize their environment, including deploying the type VI secretion system (T6SS). Acting as a bacterial crossbow, this system delivers effectors responsible for subverting host cells, killing competitors and facilitating general secretion to access common goods. Due to its importance, this lethal machine has been evolutionarily maintained, disseminated and specialized to fulfil these vital functions. In fact, T6SS structural clusters are present in over 25 % of Gram-negative bacteria, varying in number from one to six different genetic clusters per organism. Since its discovery in 2006, research on the T6SS has rapidly progressed, yielding remarkable breakthroughs. The identification and characterization of novel components of the T6SS, combined with biochemical and structural studies, have revealed fascinating mechanisms governing its assembly, loading, firing and disassembly processes. Recent findings have also demonstrated the efficacy of this system against fungal and Gram-positive cells, expanding its scope. Ongoing research continues to uncover an extensive and expanding repertoire of T6SS effectors, the genuine mediators of T6SS function. These studies are shedding light on new aspects of the biology of prokaryotic and eukaryotic organisms. This review provides a comprehensive overview of the T6SS, highlighting recent discoveries of its structure and the diversity of its effectors. Additionally, it injects a personal perspective on avenues for future research, aiming to deepen our understanding of this combative system.
细菌的生活充满挑战，为了在逆境中求存，细菌采用了一系列机制来优化其生存环境，其中包括部署 VI 型分泌系统（T6SS）。该系统犹如细菌的“弩箭”，可将效应蛋白靶向宿主细胞，从而实现破坏、杀伤竞争者以及促进一般分泌等功能，以获取公共物质。由于其重要性，这种致命机器在进化过程中被保留、传播和特化，以完成这些重要的功能。事实上，T6SS 结构簇存在于超过 25%的革兰氏阴性菌中，每个生物体的数量从一个到六个不同的遗传簇不等。自 2006 年发现以来，T6SS 的研究迅速取得进展，取得了显著的突破。T6SS 新型组件的鉴定和特性，结合生化和结构研究，揭示了其组装、加载、发射和拆卸过程的迷人机制。最近的发现还表明，该系统对真菌和革兰氏阳性细胞也具有功效，扩大了其作用范围。目前的研究仍在继续揭示 T6SS 效应器广泛而不断扩展的 repertoire，这些效应器是 T6SS 功能的真正介质。这些研究揭示了原核和真核生物生物学的新方面。本综述全面概述了 T6SS，重点介绍了其结构和效应器多样性的最新发现。此外，还注入了对未来研究途径的个人观点，旨在加深我们对这个好斗系统的理解。
