Department of Biochemistry, Genetics, and Microbiology, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Hatfield, Pretoria, South Africa.
Department of Biochemistry, Genetics, and Microbiology, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Hatfield, Pretoria, South Africa.
Microbiol Res. 2024 Jan;278:127501. doi: 10.1016/j.micres.2023.127501. Epub 2023 Sep 16.
The type 6 secretion system (T6SS) of Gram-negative bacteria (GNB) has implications for bacterial competition, virulence, and survival. For the broad host range pathogen, Pectobacterium brasiliense 1692, T6SS-mediated competition occurs in a tissue-specific manner. However, no other roles have been investigated. The aim of this study was to identify T6SS-associated proteins under virulence inducing conditions. We used Bastion tools to predict 1479 Pbr1692 secreted proteins. Sixteen percent of these overlap between type 1-4 secretion systems (T1SS-T4SS) and T6SS. Using label-free quantitative mass spectrometry of Pbr1692 T6SS active and T6SS inactive strains' secretomes cultured in minimal media supplemented with host extract, 49 T6SS-associated proteins with varied gene ontology predicted functions were identified. We report 19 and 30 T6SS primary substrates and differentially secreted proteins, respectively, in T6SS mutants versus wild type strains. Of the total 49 T6SS-associated proteins presented in this study, 25 were also predicted using the BastionX platform as T6SS exclusive and shared substrates with T1SS-T4SS. This work provides a list of Pbr1692 T6SS secreted effector candidates. These include a potential antibacterial toxin HNH endonuclease and several predicted virulence proteins, including plant cell wall degrading enzymes. A preliminary basis for potential crosstalk between GNB secretion systems is also highlighted.
革兰氏阴性菌 (GNB) 的 6 型分泌系统 (T6SS) 对细菌竞争、毒力和存活有影响。对于广泛宿主范围的病原体，巴西果胶杆菌 1692，T6SS 介导的竞争以组织特异性的方式发生。然而，尚未研究其他作用。本研究旨在鉴定在诱导毒力条件下与 T6SS 相关的蛋白质。我们使用 Bastion 工具预测了 1479 种 Pbr1692 分泌蛋白。这些蛋白中有 16%在 1-4 型分泌系统 (T1SS-T4SS) 和 T6SS 之间重叠。使用无标记定量质谱法对在含有宿主提取物的最小培养基中培养的 Pbr1692 T6SS 活性和 T6SS 非活性菌株的分泌组进行分析，鉴定出 49 种具有不同基因本体论预测功能的 T6SS 相关蛋白。我们报告了 19 种和 30 种 T6SS 初级底物和差异分泌蛋白，分别在 T6SS 突变体与野生型菌株中。在本研究中提出的总共 49 种与 T6SS 相关的蛋白质中，有 25 种也使用 BastionX 平台预测为 T6SS 特有的，并与 T1SS-T4SS 共享底物。这项工作提供了巴西果胶杆菌 1692 T6SS 分泌效应子候选物的列表。其中包括一种潜在的抗菌毒素 HNH 内切酶和几种预测的毒力蛋白，包括植物细胞壁降解酶。还强调了革兰氏阴性菌分泌系统之间潜在串扰的初步基础。
