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The type VI secretion system (T6SS) is a one step mechanism that is used widely throughout gram-negative bacterial species in injecting effector proteins and virulence factors (such as proteins, toxins, or enzymes) from across the interior (cytoplasm or cytosol) of a bacterial cell into a target cell. T6SS were first identified in 2006, when researchers at Harvard Medical School (Boston, USA) saw that mutations of Hcp and VgrG proteins in ''Vibrio cholerae'' led to decreased virulence and infectivity of the pathogen.〔 〕 . Soon afterwards, a T6SS was found in ''Pseudomonas aeruginosa'' and implicated with Hcp secretion into target cells and chronic infection . Since then, Type VI secretion systems have been found in a quarter of all proteobacterial genomes, including animal, plant, and human pathogens, as well as soil, environmental or marine bacteria. While most of the early studies of Type VI secretion focused on its role in the pathogenesis of higher organisms, more recent studies suggest a broader physiological role in defense against simple eukaryotic predators and its role in inter-bacterial interactions. ==Architecture== The Type VI Secretion system is a complex structure composed of 13 conserved proteins (which form the core subunit) and a variable amount of accessory proteins. It is often referred to as an inverted phage structure, with a 'puncturing' device at the tip of the complex which can cross target cell membranes to inject effector proteins. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Type VI secretion system」の詳細全文を読む スポンサード リンク
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