Choi Junhyeok, Lee Suhyun, Kim Dohyun, Han Yoobin, Rhyu Haerim, Lee Jisun H J, Han Sang-Wook
Department of Plant Science and Technology, Chung-Ang University, Anseong, Republic of Korea.
Front Plant Sci. 2025 May 21;16:1556578. doi: 10.3389/fpls.2025.1556578. eCollection 2025.
Glucose-1-phosphate thymidylyltransferase (GptT) is crucial for bacterial cell wall/membrane functions. However, its roles in (), the causative agent of bacterial fruit blotch (BFB) in watermelon, remain poorly understood. In this study, the roles of GptT in (GptTAc) were elucidated through proteomic and phenotypic analyses using a mutant lacking GptTAc. The virulence of the mutant was remarkably reduced in the germinated-seed inoculation and leaf infiltration. However, its growth, as assessed by optical density (OD) in rich and minimal media, was comparable to that of the wild-type strain. A comparative proteomic analysis combined with clusters of orthologous group classification revealed that GptTAc was related to diverse mechanisms, including motility and the cell wall/membrane. The mutant showed increased lipopolysaccharide production but reduced exopolysaccharide production. Additionally, biofilm formation and auto-aggregation were enhanced, while twitching halo production was diminished. Notably, the mutant was highly susceptible to multiple stress conditions-including ethylenediaminetetraacetic acid, acetic acid, cupric chloride, sodium dodecyl sulfate, and pH stress-as indicated by significantly decreased OD values or colony forming units (CFUs) compared to the wild type. Finally, the mutant strain exhibited significantly higher sensitivity to lysozyme and antibiotics targeting the bacterial cell wall or membrane, as assessed by monitoring OD or CFUs, compared to the wild-type strain. Collectively, these findings suggest that GptTAc is involved in diverse cellular functions, particularly those related to cell wall/membrane integrity. This study provides novel insights into the role of GptTAc in the virulence of , which may facilitate the identification of antivirulence agents targeting GptTAc by screening small-molecule and natural product libraries in order to control BFB.
葡萄糖-1-磷酸胸苷酰转移酶（GptT）对细菌细胞壁/膜功能至关重要。然而，其在西瓜细菌性果斑病（BFB）病原体（）中的作用仍知之甚少。在本研究中，通过对缺乏GptTAc的突变体进行蛋白质组学和表型分析，阐明了GptT在（GptTAc）中的作用。在发芽种子接种和叶片浸润实验中，该突变体的毒力显著降低。然而，通过在丰富培养基和基本培养基中的光密度（OD）评估，其生长情况与野生型菌株相当。结合直系同源簇分类的比较蛋白质组学分析表明，GptTAc与多种机制相关，包括运动性和细胞壁/膜。该突变体显示脂多糖产量增加，但胞外多糖产量减少。此外，生物膜形成和自聚集增强，而颤动晕圈产生减少。值得注意的是，与野生型相比，该突变体对多种胁迫条件高度敏感，包括乙二胺四乙酸、乙酸、氯化铜、十二烷基硫酸钠和pH胁迫，表现为OD值或菌落形成单位（CFU）显著降低。最后，与野生型菌株相比，通过监测OD或CFU评估，该突变体菌株对靶向细菌细胞壁或膜的溶菌酶和抗生素表现出显著更高的敏感性。总体而言，这些发现表明GptTAc参与多种细胞功能，特别是与细胞壁/膜完整性相关的功能。本研究为GptTAc在（）毒力中的作用提供了新的见解，这可能有助于通过筛选小分子和天然产物文库来鉴定靶向GptTAc的抗毒力剂，以控制细菌性果斑病。
