Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, USA.
mBio. 2013 Jul 23;4(4):e00374-13. doi: 10.1128/mBio.00374-13.
Swarming colonies of the bacterium Proteus mirabilis are capable of self-recognition and territorial behavior. Swarms of independent P. mirabilis isolates can recognize each other as foreign and establish a visible boundary where they meet; in contrast, genetically identical swarms merge. The ids genes, which encode self-identity proteins, are necessary but not sufficient for this territorial behavior. Here we have identified two new gene clusters: one (idr) encodes rhs-related products, and another (tss) encodes a putative type VI secretion (T6S) apparatus. The Ids and Idr proteins function independently of each other in extracellular transport and in territorial behaviors; however, these self-recognition systems are linked via this type VI secretion system. The T6S system is required for export of select Ids and Idr proteins. Our results provide a mechanistic and physiological basis for the fundamental behaviors of self-recognition and territoriality in a bacterial model system.
Our results support a model in which self-recognition in P. mirabilis is achieved by the combined action of two independent pathways linked by a shared machinery for export of encoded self-recognition elements. These proteins together form a mechanistic network for self-recognition that can serve as a foundation for examining the prevalent biological phenomena of territorial behaviors and self-recognition in a simple, bacterial model system.
变形菌属奇异变形杆菌的群体能够进行自我识别和领地行为。独立的奇异变形杆菌分离株的群体可以相互识别为外来群体，并在相遇处建立可见的边界；相比之下，遗传上相同的群体则会融合。编码自我识别蛋白的 ids 基因是这种领地行为所必需的，但不是充分条件。在这里，我们已经鉴定了两个新的基因簇：一个（idr）编码 rhs 相关产物，另一个（tss）编码一种假定的六型分泌系统（T6S）装置。Ids 和 Idr 蛋白在细胞外运输和领地行为中独立发挥作用；然而，这些自我识别系统通过这种六型分泌系统相互关联。T6S 系统是选择性输出 Ids 和 Idr 蛋白所必需的。我们的结果为细菌模型系统中自我识别和领地性的基本行为提供了机制和生理学基础。
我们的结果支持这样一种模型，即奇异变形杆菌中的自我识别是通过两种独立途径的共同作用来实现的，这两种途径通过共享的自我识别元素输出机制相互关联。这些蛋白质共同构成了自我识别的机械网络，可作为研究简单细菌模型系统中领地行为和自我识别普遍存在的生物学现象的基础。
