Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia, USA.
Department of Biology, University of Puerto Rico at Ponce, Ponce, Puerto Rico, USA.
Infect Immun. 2019 Jun 20;87(7). doi: 10.1128/IAI.00861-18. Print 2019 Jul.
is an intracellular bacterial pathogen that invades epithelial cells in the colonic mucosa, leading to bloody diarrhea. A previous study showed that forms biofilms in the presence of bile salts, through an unknown mechanism. Here, we investigated the potential role of adhesin-like autotransporter proteins in biofilm formation. BLAST search analysis revealed that the 2457T genome harbors 4 genes, , , , and , encoding adhesin-like autotransporter proteins. Deletion mutants of the , , and genes were generated and tested for biofilm formation. Phenotypic analysis of the mutant strains revealed that disruption of abolished bile salt-induced biofilm formation. IcsA is an outer membrane protein secreted at the bacterial pole that is required for actin-based motility during intracellular infection. In extracellular biofilms, IcsA was also secreted at the bacterial pole and mediated bacterial cell-cell contacts and aggregative growth in the presence of bile salts. Dissecting individual roles of bile salts showed that deoxycholate is a robust biofilm inducer compared to cholate. The release of the extracellular domain of IcsA through IcsP-mediated cleavage was greater in the presence of cholate, suggesting that the robustness of biofilm formation was inversely correlated with IcsA processing. Accordingly, deletion of abrogated IcsA processing in biofilms and enhanced biofilm formation.
是一种细胞内细菌病原体，它会入侵结肠黏膜上皮细胞，导致血性腹泻。先前的研究表明，在胆汁盐存在的情况下，通过未知机制形成生物膜。在这里，我们研究了黏附素样自转运蛋白在生物膜形成中的潜在作用。BLAST 搜索分析表明，2457T 基因组含有编码黏附素样自转运蛋白的 4 个基因、、、和。缺失突变体的、、和基因被生成并测试生物膜形成。突变株的表型分析表明，破坏基因导致胆汁盐诱导的生物膜形成被消除。IcsA 是一种在细菌极部分泌的外膜蛋白，在细胞内感染期间，是肌动蛋白依赖的运动所必需的。在细胞外生物膜中，IcsA 也在细菌极部分泌，并在胆汁盐存在下介导细菌细胞-细胞接触和聚集生长。对胆汁盐的单独作用进行剖析表明，与胆酸钠相比，脱氧胆酸钠是一种更强的生物膜诱导剂。通过 IcsP 介导的切割释放的 IcsA 细胞外结构域在胆酸钠存在下释放更多，这表明生物膜形成的稳健性与 IcsA 加工呈负相关。因此，基因的缺失消除了生物膜中 IcsA 的加工，并增强了生物膜的形成。
