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Structural basis for a bacterial Pip system plant effector recognition protein [Microbiology]
Proceedings of the National Academy of Sciences of the United States of America ( IF 11.1 ) Pub Date : 2021-03-09 , DOI: 10.1073/pnas.2019462118
Shukun Luo 1 , Bruna G Coutinho 2 , Prikshat Dadhwal 1 , Yasuhiro Oda 2 , Jiahong Ren 3 , Amy L Schaefer 2 , E Peter Greenberg 4 , Caroline S Harwood 4 , Liang Tong 5
Affiliation  

A number of plant-associated proteobacteria have LuxR family transcription factors that we refer to as PipR subfamily members. PipR proteins play roles in interactions between bacteria and their plant hosts, and some are important for bacterial virulence of plants. We identified an ethanolamine derivative, N-(2-hydroxyethyl)-2-(2-hydroxyethylamino) acetamide (HEHEAA), as a potent effector of PipR-mediated gene regulation in the plant endophyte Pseudomonas GM79. HEHEAA-dependent PipR activity requires an ATP-binding cassette-type active transport system, and the periplasmic substrate-binding protein (SBP) of that system binds HEHEAA. To begin to understand the molecular basis of PipR system responses to plant factors we crystallized a HEHEAA-responsive SBP in the free- and HEHEAA-bound forms. The SBP, which is similar to peptide-binding SBPs, was in a closed conformation. A narrow cavity at the interface of its two lobes is wide enough to bind HEHEAA, but it cannot accommodate peptides with side chains. The polar atoms of HEHEAA are recognized by hydrogen-bonding interactions, and additional SBP residues contribute to the binding site. This binding mode was confirmed by a structure-based mutational analysis. We also show that a closely related SBP from the plant pathogen Pseudomonas syringae pv tomato DC3000 does not recognize HEHEAA. However, a single amino acid substitution in the presumed effector-binding pocket of the P. syringae SBP converted it to a weak HEHEAA-binding protein. The P. syringae PipR depends on a plant effector for activity, and our findings imply that different PipR-associated SBPs bind different effectors.



中文翻译:

细菌 Pip 系统植物效应识别蛋白的结构基础 [微生物学]

许多植物相关的变形菌具有 LuxR 家族转录因子,我们将其称为 PipR 亚家族成员。PipR 蛋白在细菌与其植物宿主之间的相互作用中发挥作用,其中一些对植物的细菌毒力很重要。我们鉴定了一种乙醇胺衍生物N -(2-羟乙基)-2-(2-羟乙基氨基) 乙酰胺 (HEHEAA),它是植物内生菌假单胞菌PipR 介导的基因调控的有效效应物GM79。HEHEAA 依赖性 PipR 活性需要一个 ATP 结合盒式主动转运系统,该系统的周质底物结合蛋白 (SBP) 与 HEHEAA 结合。为了开始了解 PipR 系统对植物因子的反应的分子基础,我们结晶了游离和 HEHEAA 结合形式的 HEHEAA 响应 SBP。SBP 与肽结合 SBP 相似,处于封闭构象。它的两个叶的界面处的狭窄腔足够宽以结合 HEHEAA,但它不能容纳带有侧链的肽。HEHEAA 的极性原子被氢键相互作用识别,额外的 SBP 残基有助于结合位点。这种结合模式通过基于结构的突变分析得到证实。我们还表明,来自植物病原体的密切相关的 SBP丁香假单胞菌光伏番茄DC3000 无法识别 HEHEAA。然而,假设的丁香假单胞菌SBP 的效应子结合口袋中的单个氨基酸替换将其转化为弱的 HEHEAA 结合蛋白。在丁香假单胞菌PipR取决于植物效应的活动,我们的研究结果意味着,不同PipR相关SBPS绑定不同的效应。

更新日期:2021-03-02
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