Previously uncharacterized Salmonella enterica genes required for swarming play a role in seedling colonization
Previously uncharacterized Salmonella enterica genes required for swarming play a role in seedling colonization
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DOI：
10.1099/mic.0.032029-0
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发表时间：
2009-11-01
期刊：
影响因子：
2.8
通讯作者：
Narm, Koh-Eun
中科院分区：
文献类型：
--
作者：
Barak, Jeri D.;Gorski, Lisa;Narm, Koh-Eun
由食用新鲜农产品引起的细菌性食源性疾病的发病率正在上升。这不是由于偶然的污染，而是动物病原体肠道沙门氏菌利用特定的分子机制附着并定殖植物。这项工作的特点是两个S。肠道基因的未知功能：一个假定的周质蛋白，STM 0278，和一个假定的蛋白质与水解酶的C-末端，STIM 0650。STM 0278和STM 0650对幼苗定殖很重要，但在定殖过程中似乎有不同的作用。STM 0278或STM 0650的突变体在24 h时显示出苜蓿幼苗的定殖减少，STM 0278突变体在48 h时也显示出定殖减少。这两个基因在植物中表达，在4小时后接种3天的幼苗和种子接种后72小时。这表明STM 0650在幼苗定殖中的作用在该过程的后期不太重要，或者被其他机制复制。STM 0278和STM 0650的突变体在群集方面有缺陷。STM 0278突变体在24 h内未能群集，而STM 0650突变体的群集被延迟。添加表面活性剂恢复了STM 0278突变体的群集，表明STM 0278参与表面活性剂或渗透剂的产生或部署。苜蓿种子分泌物作为唯一营养源能够使S.肠道菌群序列分析表明，在植物相关细菌中与STM 0278和STM 0650同源，但在大肠杆菌中没有同源性。STM 0650的系统发育分析显示了来自不同种类的植物相关细菌的相似序列。优先在根部定居的细菌，包括S。enterica，可以使用类似的水解酶用于植物上的群集或生物膜产生。多细胞行为S. enterica出现中央植物定植。S.参与植物定殖和在宿主外存活的肠杆菌基因最有可能是这种细菌的“功能未知”基因。
Incidences of bacterial foodborne illness caused by ingestion of fresh produce are rising. Instead of this being due to incidental contamination, the animal pathogen Salmonella enterica utilizes specific molecular mechanisms to attach to and colonize plants. This work characterizes two S. enterica genes of unknown function: a putative periplasmic protein, STM0278, and a putative protein with a hydrolase in the C-terminus, STIM0650. STM0278 and STM0650 are important for seedling colonization but appear to have different roles during the process of colonization. Mutants of either STM0278 or STM0650 showed reduced colonization of alfalfa seedlings at 24 h, and the STM0278 mutant also showed reduced colonization at 48 h. Both genes were expressed in planta at 4 h following inoculation of 3-day-old seedlings and at 72 h after seed inoculation. This suggests that the role of STM0650 in seedling colonization is less important later in the process or is duplicated by other mechanisms. Mutants of STM0278 and STM0650 were defective in swarming. The STM0278 mutant failed to swarm in 24 h, while swarming of the STM0650 mutant was delayed. Addition of surfactant restored swarming of the STM0278 mutant, suggesting that STM0278 is involved in surfactant or osmotic agent production or deployment. Alfalfa seed exudates as the sole nutrient source were capable of perpetuating S. enterica swarming. Sequence analysis revealed sequences homologous to STM0278 and STM0650 in plant-associated bacteria, but none in Escherichia coli. Phylogenetic analysis of STM0650 showed similar sequences from diverse classes of plant-associated bacteria. Bacteria that preferentially colonize roots, including S. enterica, may use a similar hydrolase for swarming or biofilm production on plants. Multicellular behaviours by S. enterica appear central to plant colonization. S. enterica genes involved in plant colonization and survival outside of a host are most likely among the 'function unknown' genes of this bacterium.