Scala Valeria, Salustri Manuel, Merfa Marcus Vinicius, Beccaccioli Marzia, Lascala Leonardo, De La Fuente Leonardo, Reverberi Massimo
Council for Agricultural Research and Economics, Research Centre for Plant Protection and Certification of Rome, 00156, Rome, Italy.
Department of Environmental Biology, Sapienza University of Rome, Rome, Italy.
Mol Biol Rep. 2025 Feb 25;52(1):263. doi: 10.1007/s11033-025-10259-y.
The oxylipins 10-HpOME and 7,10-DiHoME derive from oleic acid and have been extensively studied for their ability to regulate contractions, microcolony formation and biofilm formation in the model organism Pseudomonas aeruginosa.
Xylella fastidiosa subsp. pauca strain de Donno has been reported to produce 10-HpOME and 7,10-DiHOME in vivo when inoculated in the model plant Nicotiana tabacum or in naturally occurring infected olive trees. In this study, we deciphered the relationship among cell adhesion and oxylipins in Xylella fastidiosa subsp. fastidiosa (Temecula1 strain) and subsp. multiplex (AlmaEM3 strain). The role of the PD0744 gene, encoding for XadA2, a non-fimbrial adhesin belonging to the trimeric autotransporter family, probably involved in the surface attachment required in the initial phase of biofilm formation was investigated. PD0744 deletion mutants in two X. fastidiosa strains were generated, through homologous recombination, and the impact of its deletion on bacterial lifestyle was assessed. In vitro assays were performed to characterize the mutant phenotype, particularly in twitching motility and its capability to grow and form biofilm. Mutants showed a reduced twitching motility and biofilm formation compared to wild type strains. HPLC-MS/MS analysis revealed a decrease in 7,10-DiHOME production together with an increase of its precursor 10-HpOME in the mutants.
7,10-DiHOME could be a crucial signaling molecule to promote biofilm formation and twitching motility, whose synthesis likely depends on a signal transduction requiring the presence of the adhesin XadA2 and thus not working if this protein is depleted. These results help understanding the complex regulation of biofilm formation in this devastating pathogen.
氧脂类物质10-HpOME和7,10-DiHoME来源于油酸，并且因其调节模式生物铜绿假单胞菌收缩、微菌落形成和生物膜形成的能力而受到广泛研究。
据报道，当接种于模式植物烟草或自然感染的橄榄树中时，桑氏木质部菌亚种pauca菌株de Donno在体内会产生10-HpOME和7,10-DiHOME。在本研究中，我们解析了木质部菌亚种fastidiosa（Temecula1菌株）和亚种multiplex（AlmaEM3菌株）中细胞黏附与氧脂类物质之间的关系。研究了编码XadA2的PD0744基因的作用，XadA2是一种属于三聚体自转运蛋白家族的非菌毛黏附素，可能参与生物膜形成初始阶段所需的表面附着。通过同源重组构建了两种木质部菌菌株的PD0744缺失突变体，并评估了其缺失对细菌生活方式的影响。进行体外试验以表征突变体表型，特别是在颤动运动及其生长和形成生物膜的能力方面。与野生型菌株相比，突变体的颤动运动和生物膜形成减少。HPLC-MS/MS分析显示，突变体中7,10-DiHOME的产量降低，同时其前体10-HpOME的产量增加。
7,10-DiHOME可能是促进生物膜形成和颤动运动的关键信号分子，其合成可能依赖于需要黏附素XadA2存在的信号转导，因此如果该蛋白缺失则无法发挥作用。这些结果有助于理解这种毁灭性病原体中生物膜形成的复杂调控。
