Fauvart Maarten, Michiels Jan
Centre of Microbial and Plant Genetics, K.U. Leuven, Leuven, Belgium.
FEMS Microbiol Lett. 2008 Aug;285(1):1-9. doi: 10.1111/j.1574-6968.2008.01254.x.
Rhizobia are Gram-negative bacteria than can elicit the formation of specialized organs, called root nodules, on leguminous host plants. Upon infection of the nodules, they differentiate into nitrogen-fixing bacteroids. An elaborate signal exchange precedes the symbiotic interaction. In general, both rhizobia and host plants exhibit narrow specificity. Rhizobial factors contributing to this specificity include Nod factors and surface polysaccharides. It is becoming increasingly clear that protein secretion is important in determining the outcome of the interaction as well. This paper discusses our current understanding of the symbiotic role played by rhizobial secreted proteins, transported both by secretion systems that are of general use, such as the type I secretion system, and by specialized, host-targeting secretion systems, such as the type III, type IV and type VI secretion systems.
根瘤菌是革兰氏阴性菌，能够在豆科宿主植物上诱导形成称为根瘤的特殊器官。在根瘤被感染后，它们会分化为固氮类菌体。在共生相互作用之前会有一系列复杂的信号交换。一般来说，根瘤菌和宿主植物都表现出狭窄的特异性。促成这种特异性的根瘤菌因子包括结瘤因子和表面多糖。越来越清楚的是，蛋白质分泌在决定相互作用的结果方面也很重要。本文讨论了我们目前对根瘤菌分泌蛋白在共生中所起作用的理解，这些蛋白通过一般使用的分泌系统（如I型分泌系统）以及专门针对宿主的分泌系统（如III型、IV型和VI型分泌系统）进行运输。
