Proline antagonizes GABA-induced quenching of quorum-sensing in Agrobacterium tumefaciens
Proline antagonizes GABA-induced quenching of quorum-sensing in Agrobacterium tumefaciens
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DOI：
10.1073/pnas.0808005106
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发表时间：
2009-08-25
影响因子：
11.1
通讯作者：
Faure, D.
中科院分区：
文献类型：
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作者：
Haudecoeur, E.;Planamentea, S.;Faure, D.
植物积累游离L-脯氨酸（Pro）响应非生物胁迫（干旱和盐度）和细菌病原体，包括肿瘤诱导细菌根癌农杆菌的存在。但Pro积累在寄主-病原互作中的作用尚不清楚。在这里，我们证明了Pro在A.通过干扰GABA的输入，从而干扰GABA诱导的细菌群体感应信号3-氧代-辛酰基高丝氨酸内酯的降解，从而抑制根癌农杆菌C58诱导的肿瘤。我们鉴定了一种细菌受体Atu 2422，它与GABA和Pro的摄取有关，表明Pro是GABA信号传导的天然拮抗剂。Atu 2422氨基酸序列含有在人GABA（B）受体中捕获GABA所需的捕蝇草结构域。构建的atu 2422突变体比野生型细菌更具毒性;此外，具有低水平的Pro的转基因植物表现出不太严重的肿瘤症状比他们的野生型父母，揭示了金星捕蝇草GABA受体和相对丰富的GABA和Pro在宿主-病原体相互作用的关键作用。
Plants accumulate free L-proline (Pro) in response to abiotic stresses (drought and salinity) and presence of bacterial pathogens, including the tumor-inducing bacterium Agrobacterium tumefaciens. However, the function of Pro accumulation in host-pathogen interaction is still unclear. Here, we demonstrated that Pro antagonizes plant GABA-defense in the A. tumefaciens C58-induced tumor by interfering with the import of GABA and consequently the GABA-induced degradation of the bacterial quorum-sensing signal, 3-oxo-octanoylhomoserine lactone. We identified a bacterial receptor Atu2422, which is implicated in the uptake of GABA and Pro, suggesting that Pro acts as a natural antagonist of GABA-signaling. The Atu2422 amino acid sequence contains a Venus flytrap domain that is required for trapping GABA in human GABA(B) receptors. A constructed atu2422 mutant was more virulent than the wild type bacterium; moreover, transgenic plants with a low level of Pro exhibited less severe tumor symptoms than did their wild-type parents, revealing a crucial role for Venus flytrap GABA-receptor and relative abundance of GABA and Pro in host-pathogen interaction.