Xylella fastidiosa is a xylem-limited bacterial pathogen that causes Pierce's disease (PD) of grapevine. In host plants, this bacterium exclusively colonizes the xylem, which is primarily non-living at maturity. Understanding how X. fastidiosa interfaces with this specialized conductive tissue is at the forefront of investigation for this pathosystem. Unlike many bacterial plant pathogens, X. fastidiosa lacks a type III secretion system and cognate effectors that aid in host colonization. Instead, X. fastidiosa utilizes plant cell-wall hydrolytic enzymes and lipases as part of its xylem colonization strategy. Several of these virulence factors are predicted to be secreted via the type II secretion system (T2SS), the main terminal branch of the Sec-dependent general secretory pathway. In this study, we constructed null mutants in xpsE and xpsG, which encode for the ATPase that drives the T2SS and the major structural pseudopilin of the T2SS, respectively. Both mutants were non-pathogenic and unable to effectively colonize Vitis vinifera grapevines, demonstrating that the T2SS is required for X. fastidiosa infection processes. Furthermore, we utilized mass spectrometry to identify type II-dependent proteins in the X. fastidiosa secretome. In vitro, we identified six type II-dependent proteins in the secretome that included three lipases, a β-1,4-cellobiohydrolase, a protease, and a conserved hypothetical protein. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

中文翻译：

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葡萄树中的苛养木杆菌需要 II 型分泌系统才能致病和存活。

Xylella fastidiosa 是一种限制木质部的细菌病原体，可引起葡萄树皮尔斯病 (PD)。在寄主植物中，这种细菌专门定植于木质部，木质部在成熟时主要是无生命的。了解 X. fastidiosa 如何与这种特殊的传导组织相互作用是该病理系统研究的前沿。与许多细菌性植物病原体不同，X. fastidiosa 缺乏 III 型分泌系统和有助于宿主定植的同源效应子。相反，X. fastidiosa 利用植物细胞壁水解酶和脂肪酶作为其木质部定植策略的一部分。预计其中一些毒力因子将通过 II 型分泌系统 (T2SS) 分泌，该系统是 Sec 依赖性一般分泌途径的主要末端分支。在本研究中，我们在 xpsE 和 xpsG 中构建了无效突变体，它们分别编码驱动 T2SS 的 ATP 酶和 T2SS 的主要结构假菌毛蛋白。两种突变体都是非致病性的，并且无法有效地在葡萄树上定殖，这表明 T2SS 是 X. fastidiosa 感染过程所必需的。此外，我们利用质谱法鉴定了 X. fastidiosa 分泌组中的 II 型依赖性蛋白。在体外，我们在分泌蛋白组中鉴定了六种 II 型依赖性蛋白，其中包括三种脂肪酶、一种 β-1,4-纤维二糖水解酶、一种蛋白酶和一种保守的假设蛋白。[公式：见文字] 版权所有 © 2023 作者。这是一篇根据 CC BY-NC-ND 4.0 国际许可证分发的开放获取文章。