Contact-dependent killing by Caulobacter crescentus via cell surface-associated, glycine zipper proteins
Contact-dependent killing by Caulobacter crescentus via cell surface-associated, glycine zipper proteins
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DOI：
10.7554/elife.24869
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发表时间：
2017-03-21
期刊：
影响因子：
7.7
通讯作者：
Laub, Michael T.
中科院分区：
文献类型：
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作者：
Garcia-Bayona, Lenor;Guo, Monica S.;Laub, Michael T.
大多数细菌与其他物种激烈竞争有限的营养物质。一些细菌可以通过分泌细菌素来杀死附近的细胞，细菌素是一种多种蛋白质抗菌剂。然而，细菌素通常是自由扩散的，因此对水环境中的浮游细胞没有什么价值。在这里，我们发现了一种非典型的双蛋白细菌素，它保留在生产者细胞的表面，在那里它介导细胞接触依赖性杀伤。细菌素样蛋白CdzC和CdzD含有甘氨酸拉链基序，通常存在于淀粉样蛋白中，CdzC在产生细胞表面形成大的不溶性聚集体。这些聚集体可以驱动接触依赖性杀死其他生物体，或不产生Cdzl免疫蛋白的根状杆菌细胞。Cdz系统使用I型分泌系统，与先前描述的接触依赖性抑制系统无关。然而，在许多细菌中发现了cdz样系统，这表明这种形式的接触依赖性抑制是常见的。
Most bacteria are in fierce competition with other species for limited nutrients. Some bacteria can kill nearby cells by secreting bacteriocins, a diverse group of proteinaceous antimicrobials. However, bacteriocins are typically freely diffusible, and so of little value to planktonic cells in aqueous environments. Here, we identify an atypical two-protein bacteriocin in the alpha-proteobacterium Caulobacter crescentus that is retained on the surface of producer cells where it mediates cell contact-dependent killing. The bacteriocin-like proteins CdzC and CdzD harbor glycine-zipper motifs, often found in amyloids, and CdzC forms large, insoluble aggregates on the surface of producer cells. These aggregates can drive contact-dependent killing of other organisms, or Caulobacter cells not producing the Cdzl immunity protein. The Cdz system uses a type I secretion system and is unrelated to previously described contact-dependent inhibition systems. However, Cdz-like systems are found in many bacteria, suggesting that this form of contact-dependent inhibition is common.