Discrete cyclic di-GMP-dependent control of bacterial predation versus axenic growth in Bdellovibrio bacteriovorus.
Discrete cyclic di-GMP-dependent control of bacterial predation versus axenic growth in Bdellovibrio bacteriovorus.
复制标题
DOI：
10.1371/journal.ppat.1002493
复制
发表时间：
2012-02
期刊：
影响因子：
6.7
通讯作者：
Sockett RE
中科院分区：
文献类型：
--
作者：
Hobley L;Fung RK;Lambert C;Harris MA;Dabhi JM;King SS;Basford SM;Uchida K;Till R;Ahmad R;Aizawa S;Gomelsky M;Sockett RE
噬菌蛭弧菌（Bdellovibrio bacteriovorus）是一种在自由生长和捕食革兰氏阴性菌（包括人、动物和植物的重要病原体）之间振荡的δ-变形杆菌。在进入猎物周质后，杀死猎物并在猎物原生质体内复制，几个能动的B。噬菌后代细胞出现。B。噬菌HD 100基因组编码许多蛋白质，这些蛋白质被预测参与通过第二信使环状二-GMP（c-di-GMP）的信号传导，已知其影响细菌的生活方式选择。我们研究了c-di-GMP信号在B中的作用。本研究主要集中在五种GGDEF结构域蛋白上，这些蛋白被预测作为引发c-di-GMP信号级联的二鸟苷酰环化酶发挥作用。个别GGDEF结构域基因的失活导致显著不同的表型。缺失dgcB（Bd 0742）导致捕食受损，专性无菌突变体，而缺失dgcC（Bd 1434）导致相反的，专性捕食突变体。缺失dgcA（Bd 0367）废除滑行运动，产生的细菌能够掠夺性入侵，但无法离开疲惫的猎物。用野生型dgc基因实现了互补，但用GGAAF版本则没有。cdgA（Bd 3125）的缺失大大减缓捕食，这是恢复野生型互补。缺失dgcD（Bd 3766）没有可观察到的表型。体外分析表明DgcA、DgcB和DgcC是二鸟苷酸环化酶。CdgA缺乏酶活性，但在DgcB途径中作为c-di-GMP受体发挥作用。未检测到DgcD活性。DgcA的缺失强烈地降低了纯蛭弧菌细胞的可提取的c-di-GMP含量。我们发现，c-di-GMP信号通路是必不可少的自由生活和掠夺性的生活方式的B。因此，可以使dgcC-和专性捕食性dgcC-在没有细菌病原体捕食的情况下缺乏存活的倾向，因此可能用于抗病原体应用。与其他细菌中的许多研究相反，蛭弧菌在c-di-GMP信号通路中显示出特异性和缺乏重叠。 噬菌蛭弧菌是一种微小的细菌，捕食其他细菌，包括引起人类，动物或作物感染的病原菌。蛭弧菌不会攻击人类、植物或动物细胞，因此在未来可能被用作“活抗生素”。在这里，我们发现，使用遗传化学分析和显微镜，蛋白质中的一个序列称为“GGDEF”控制蛭弧菌是否通过捕食其他细菌生长，或者它们是否在不攻击猎物的情况下“正常”生长。GGDEF蛋白质都合成小信号分子环二GMP，但有趣的是，这种信号的产生有不同的影响，这取决于GGDEF蛋白质。如果我们去除一个GGDEF蛋白质，这使得蛭弧菌不能再吃细菌，必须依靠环境营养物质生存。去除一种不同的GGDEF蛋白质会使蛭弧菌只能通过吃猎物细菌如病原体来生存-它们失去了吃“正常”营养物质的能力。当试图生产蛭弧菌作为治疗时，这是非常有用的。例如，正确的GGDEF突变体只能“吃”病原体，不能使用伤口血液和血清中的营养物质生长，因此这将是一种自限性治疗。
Bdellovibrio bacteriovorus is a Delta-proteobacterium that oscillates between free-living growth and predation on Gram-negative bacteria including important pathogens of man, animals and plants. After entering the prey periplasm, killing the prey and replicating inside the prey bdelloplast, several motile B. bacteriovorus progeny cells emerge. The B. bacteriovorus HD100 genome encodes numerous proteins predicted to be involved in signalling via the secondary messenger cyclic di-GMP (c-di-GMP), which is known to affect bacterial lifestyle choices. We investigated the role of c-di-GMP signalling in B. bacteriovorus, focussing on the five GGDEF domain proteins that are predicted to function as diguanylyl cyclases initiating c-di-GMP signalling cascades. Inactivation of individual GGDEF domain genes resulted in remarkably distinct phenotypes. Deletion of dgcB (Bd0742) resulted in a predation impaired, obligately axenic mutant, while deletion of dgcC (Bd1434) resulted in the opposite, obligately predatory mutant. Deletion of dgcA (Bd0367) abolished gliding motility, producing bacteria capable of predatory invasion but unable to leave the exhausted prey. Complementation was achieved with wild type dgc genes, but not with GGAAF versions. Deletion of cdgA (Bd3125) substantially slowed predation; this was restored by wild type complementation. Deletion of dgcD (Bd3766) had no observable phenotype. In vitro assays showed that DgcA, DgcB, and DgcC were diguanylyl cyclases. CdgA lacks enzymatic activity but functions as a c-di-GMP receptor apparently in the DgcB pathway. Activity of DgcD was not detected. Deletion of DgcA strongly decreased the extractable c-di-GMP content of axenic Bdellovibrio cells. We show that c-di-GMP signalling pathways are essential for both the free-living and predatory lifestyles of B. bacteriovorus and that obligately predatory dgcC- can be made lacking a propensity to survive without predation of bacterial pathogens and thus possibly useful in anti-pathogen applications. In contrast to many studies in other bacteria, Bdellovibrio shows specificity and lack of overlap in c-di-GMP signalling pathways. Bdellovibrio bacteriovorus is a tiny bacterium that preys upon other bacteria including pathogenic bacteria that cause infections in humans, animals, or crop plants. Bdellovibrio don't attack human, plant or animal cells and so could in future be used as “living antibiotics”. Here we have discovered, using genetics chemical analyses and microscopy, that proteins with a sequence in them called “GGDEF” control whether Bdellovibrio grow by preying upon other bacteria or whether they grow “normally” without attacking prey. The GGDEF proteins all synthesise the small signalling molecule cyclic- di GMP, but interestingly the production of this signal has different effects depending on which GGDEF protein makes it. If we remove one GGDEF protein this makes a Bdellovibrio that can't eat bacteria anymore and has to survive on environmental nutrients. Removing a different GGDEF protein gives Bdellovibrio that can only survive by eating prey bacteria such as pathogens- they lose the ability to eat “normal” nutrients. This is very useful when trying to produce Bdellovibrio as a therapy. The correct GGDEF mutant would have to “eat” pathogens only and couldn't grow using the nutrients present in the blood and serum of a wound, for example, so it would be a self-limiting treatment.
登录
查看更多内容
影响因子：
3.6
作者：
Bobrov AG;Kirillina O;Ryjenkov DA;Waters CM;Price PA;Fetherston JD;Mack D;Goldman WE;Gomelsky M;Perry RD
通讯作者：
Perry RD
二甘氨酸酸环化酶反应调节剂WSPR激活和自抑制的决定因素。
影响因子：
5.6
作者：
De, Nabanita;Navarro, Marcos V. A. S.;Raghavan, Rahul V.;Sondermann, Holger
通讯作者：
Sondermann, Holger
影响因子：
4.2
作者：
Galperin MY
通讯作者：
Galperin MY
影响因子：
5.6
作者：
Ko, M;Park, C
通讯作者：
Park, C
影响因子：
3.2
作者：
Evans, Katy J.;Lambert, Carey;Sockett, R. Elizabeth
通讯作者：
Sockett, R. Elizabeth