Plants genetically modified by the pathogenic Agrobacterium strain C58 synthesize agrocinopines A and B, whereas those modified by the pathogenic strain Bo542 produce agrocinopines C and D. The four agrocinopines (A, B, C and D) serve as nutrients by agrobacteria and signaling molecule for the dissemination of virulence genes. They share the uncommon pyranose-2-phosphate motif, represented by the l-arabinopyranose moiety in agrocinopines A/B and the d-glucopyranose moiety in agrocinopines C/D, also found in the antibiotic agrocin 84. They are imported into agrobacterial cytoplasm via the Acc transport system, including the solute-binding protein AccA coupled to an ABC transporter. We have previously shown that unexpectedly, AccA from strain C58 (AccAC58) recognizes the pyranose-2-phosphate motif present in all four agrocinopines and agrocin 84, meaning that strain C58 is able to import agrocinopines C/D, originating from the competitor strain Bo542. Here, using agrocinopine derivatives and combining crystallography, affinity and stability measurements, modeling, molecular dynamics, in vitro and vivo assays, we show that AccABo542 and AccAC58 behave differently despite 75% sequence identity and a nearly identical ligand binding site. Indeed, strain Bo542 imports only compounds containing the d-glucopyranose-2-phosphate moiety, and with a lower affinity compared with strain C58. This difference in import efficiency makes C58 more competitive than Bo542 in culture media. We can now explain why Agrobacterium/Allorhizobium vitis strain S4 is insensitive to agrocin 84, although its genome contains a conserved Acc transport system. Overall, our work highlights AccA proteins as a case study, for which stability and dynamics drive specificity.

中文翻译：

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农杆菌中抗生素和群体感应调节剂的 AccA 转运蛋白高度保守的配体结合位点导致不同的特异性

经致病性农杆菌菌株 C58 基因改造的植物合成农杆菌素 A 和 B，而经致病性菌株 Bo542 基因改造的植物则产生农杆菌素 C 和 D。四种农杆菌素（A、B、C 和 D）作为农杆菌的营养物质和信号分子毒力基因的传播。它们共享不常见的吡喃糖-2-磷酸基序，以农杆菌A/B中的l-阿拉伯吡喃糖部分和农杆菌碱C/D中的d-吡喃葡萄糖部分为代表，也存在于抗生素agrocin 84中。它们通过Acc 转运系统，包括与 ABC 转运蛋白偶联的溶质结合蛋白 AccA。我们之前已经表明，出乎意料的是，菌株 C58 (AccAC58) 的 AccA 识别所有四种农杆菌素和农杆菌素 84 中存在的吡喃糖-2-磷酸基序，这意味着菌株 C58 能够导入源自竞争菌株 Bo542 的农杆菌素 C/D 。在这里，使用农杆菌素衍生物并结合晶体学、亲和力和稳定性测量、建模、分子动力学、体外和体内测定，我们表明尽管 AccABo542 和 AccAC58 具有 75% 的序列同一性和几乎相同的配体结合位点，但其表现不同。事实上，菌株 Bo542 仅导入含有 d-吡喃葡萄糖-2-磷酸部分的化合物，并且与菌株 C58 相比亲和力较低。这种导入效率的差异使得C58在培养基中比Bo542更具竞争力。我们现在可以解释为什么农杆菌/异根瘤菌菌株 S4 对农杆菌素 84 不敏感，尽管其基因组包含保守的 Acc 转运系统。总的来说，我们的工作强调 AccA 蛋白作为案例研究，其稳定性和动态性驱动特异性。