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Reference.org
Type VI secretion system
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<p>The type VI secretion system (T6SS) is one of the <a href="/facts/Bacterial_secretion_system/fYgCqhak">bacterial secretion systems</a>, membrane protein complexes, used by a wide range of <a href="/facts/Gram-negative_bacteria/S1PbVtp4">gram-negative bacteria</a> to transport <a href="/facts/Bacterial_effector_protein/2xo5F3fF">effectors</a>. Effectors are moved from the interior of a bacterial cell, across the membrane into an adjacent target cell. While often reported that the T6SS was discovered in 2006 by researchers studying the causative agent of <a href="/facts/Cholera/rk8JfWEp">cholera</a>, <i><a href="/facts/Vibrio_cholerae/DbjgMz9Y">Vibrio cholerae</a></i>, the first study demonstrating that T6SS genes encode a protein export apparatus was actually published in 2004, in a study of protein secretion by the fish pathogen <i><a href="/facts/Edwardsiella_tarda/8wzyfnjo">Edwardsiella tarda</a></i>. </p><p>Since then, it is estimated that at least a quarter of all pathogenic and non-pathogenic proteobacterial <a href="/facts/Genomes/tjhWET4V">genomes</a> encode for a T6SS, including pathogens of animals, plants, and humans, as well as soil, environmental or marine bacteria. Genes encoding for the T6SSs are commonly found chromosomally, but can also be harboured in <a href="/facts/Mobile_genetic_elements/cmVCkbA7">mobile genetic elements</a> and on <a href="/facts/Plasmids/yf59JVlA">plasmids</a> mediating their transfer and increase in genetic diversity. While most of the early studies of Type VI secretion focused on its role in the pathogenesis of higher organisms, it is now known to function primarily in interbacterial antagonism. Studies have also shown that T6SS plays a role in the acquisition of essential metals, such as manganese and iron, from the surrounding environment. This ability allows bacteria to outcompete rivals for these nutrients while fostering cooperation with related bacterial cells. This suggests that T6SS plays a critical role in maintaining microbial community stability by balancing cooperation and competition. </p>