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首页> 外文期刊>Journal of Molecular Biology >Structures of the Ultra-High-Affinity Protein-Protein Complexes of Pyocins S2 and AP41 and Their Cognate Immunity Proteins from Pseudomonas aeruginosa
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Structures of the Ultra-High-Affinity Protein-Protein Complexes of Pyocins S2 and AP41 and Their Cognate Immunity Proteins from Pseudomonas aeruginosa

机译：铜绿假单胞菌的Pyocins S2和AP41及其同源免疫蛋白的超高亲和力蛋白质复合物的结构。

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How ultra-high-affinity protein protein interactions retain high specificity is still poorly understood. The interaction between colicin DNase domains and their inhibitory immunity (Im) proteins is an ultra-high-affinity interaction that is essential for the neutralisation of endogenous DNase catalytic activity and for protection against exogenous DNase bacteriocins. The colicin DNase-Im interaction is a model system for the study of high-affinity protein protein interactions. However, despite the fact that closely related colicin-like bacteriocins are widely produced by Gram-negative bacteria, this interaction has only been studied using colicins from Escherichia coli. In this work, we present the first crystal structures of two pyocin DNase-Im complexes from Pseudomonas aeruginosa, pyocin S2 DNase-ImS2 and pyocin AP41 DNase-ImAP41. These structures represent divergent DNase Im subfamilies and are important in extending our understanding of protein protein interactions for this important class of high-affinity protein complex. A key finding of this work is that mutations within the immunity protein binding energy hotspot, helix III, are tolerated by complementary substitutions at the DNase Immunity protein binding interface. Im helix III is strictly conserved in colicins where an Asp forms polar interactions with the DNase backbone. ImAP41 contains an Asp-to-Gly substitution in helix III and our structures show the role of a co-evolved substitution where Pro in DNase loop 4 occupies the volume vacated and removes the unfulfilled hydrogen bond. We observe the co-evolved mutations in other DNase Immunity pairs that appear to underpin the split of this family into two distinct groups. (C) 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
机译：超高亲和力蛋白质蛋白质相互作用如何保持高特异性仍知之甚少。大肠菌素DNase结构域与其抑制性免疫（Im）蛋白之间的相互作用是超高亲和力相互作用，对于中和内源DNase催化活性和防止外源DNase细菌素至关重要。大肠菌素DNase-Im相互作用是用于研究高亲和力蛋白蛋白质相互作用的模型系统。然而，尽管事实上革兰氏阴性菌广泛产生密切相关的类大肠菌素样细菌素，但仅使用大肠杆菌的大肠菌素研究了这种相互作用。在这项工作中，我们介绍了来自铜绿假单胞菌的两种脓素DNase-Im复合物，脓素S2 DNase-ImS2和脓素AP41 DNase-ImAP41的第一个晶体结构。这些结构代表了不同的DNase Im亚家族，对于扩展我们对这一重要类别的高亲和力蛋白质复合物的蛋白质相互作用的理解至关重要。这项工作的关键发现是DNase Immunity蛋白质结合界面处的互补取代可耐受免疫蛋白结合能热点Hlix III中的突变。 Im helix III在大肠菌素中是严格保守的，其中Asp与DNase骨架形成极性相互作用。 ImAP41在螺旋III中包含一个Asp-to-Gly取代基，我们的结构显示了共进化取代基的作用，其中DNase环4中的Pro占据了空出的体积，并去除了未完成的氢键。我们观察到了其他DNase免疫对中共同进化的突变，这些突变似乎支持了该家族分为两个不同的群体。 （C）2015作者。由Elsevier Ltd.发行。这是CC BY许可下的开放访问文章（http://creativecommons.org/licenses/by/4.0/）。

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