Self-nonself recognition and multicellularity in myxobacteria: Equipment supplement

摘要（来自母基金R35 GM 140886） 生物学中的一个基本问题是多细胞生物体中的单个细胞 将其他细胞视为自我，以便在组织、器官和整个个体中协同发挥作用。 为了解决这个复杂的问题，我们研究了一个相对简单的实验跟踪 模式生物，黄色粘球菌。虽然是一种细菌，M. xanthus表现出许多特性 存在于组织和更复杂的多细胞物种中。一个特征是多细胞发育 以应对饥饿。我们发现，另一个特征是细胞区分 在自我和非自我之间交换细胞蛋白质和脂质。识别是介导的 一种叫做TraA和它的伴侣TraB的多态性细胞表面受体。只有细胞 相同或几乎相同的TraA受体参与同型相互作用。社会成果 从这个过程中，所谓的外膜交换（OME），根据不同的性质， 相互作用的细胞。在某些情况下，OME导致合作互动， 捐赠者通过补充细胞成分来修复受损细胞。在其他情况下，OME导致 当配对细胞不是克隆时的拮抗作用。通过多态性毒素进行区分 转移到缺乏同源免疫的受体细胞。 我们未来的目标是多方面的，以了解OME，更广泛地说，如何 细胞识别自我并向多细胞过渡。未来五年，我们将 批判性地研究OME如何导致合作性。研究的一个领域是TraA/B 指导群体中的紧急行为，包括同步和协调 动作这将通过监测全局基因表达以及TraA/B如何影响 与控制运动性的信号转导途径相互作用。细胞同步正在 用生物传感器监测细胞中钙的流动。其他方法将探讨如何 M. xanthus响应和适应环境压力，从而这些适应是 通过OME转移到幼稚人群中。第二个研究领域是粘细菌 在自然环境中迅速分化成不同的社会群体。我们的初步研究结果 表明通过非裂解转导颗粒介导群体水平基因转移 通过携带与社会歧视有关的多态性基因而产生的分歧。第三个重点领域 将阐明OME的机制，认为涉及外膜融合。最后我们将 探索自我识别的新机制及其在多细胞生命中的作用。

Abstract (from parent grant R35GM140886) A fundamental question in biology is how individual cells within a multicellular organism recognize other cells as self to cooperatively function in tissues, organs and as whole individuals. To address this complex question, we study a relatively simple and experimentally trackable model organism, Myxococcus xanthus. Although a bacterium, M. xanthus exhibits many traits found in tissues and more complex multicellular species. One trait is multicellular development in response to starvation. Another trait, we discovered, is the ability of cells to distinguish between self and nonself for the exchange of cellular proteins and lipids. Recognition is mediated by a polymorphic cell surface receptor called TraA and its partner TraB. Only cells that bear identical or nearly identical TraA receptors engage by homotypic interactions. Social outcomes from this process, called outer membrane exchange (OME), vary depending on the properties of the interacting cells. In some cases, OME leads to cooperative interactions whereby healthy donors repair damaged cells by replenishing their cell components. In other cases, OME leads to antagonism when partnering cells are not clonal. Discrimination occurs by polymorphic toxin transfer to recipient cells that lack cognate immunity. Our future goals are multifaceted with respect to understanding OME and, more broadly, how cells recognize self and transition toward multicellularity. Over the next five years we will critically examine how OME leads to cooperativity. One area of investigation is how TraA/B directs emergent behaviors in populations that include synchronized and coordinated movements. This will be explored by monitoring global gene expression and how TraA/B interacts with a signal transduction pathway that controls motility. Cell synchronization is being studied with a biosensor the monitors’ calcium fluxes in cells. Other approaches will probe how M. xanthus responds and adapts to environmental stresses, whereby those adaptations are transferred to naïve populations by OME. A second area of research addresses how myxobacteria rapidly diverge into different social groups in natural environments. Our preliminary findings indicate that horizontal gene transfer by non-lytic transducing particles mediate population divergence by carrying polymorphic genes involved in social discrimination. A third focus area will elucidate the mechanism of OME thought to involve outer membrane fusion. Finally, we will explore new mechanisms of self-recognition and its role in multicellular life.