C-Signal-Dependent Gene Expression in Myxococcus Xanthus

在自然界中，细菌通常作为称为生物膜的复杂群落的成员而存在。细胞在生物膜内相互作用，向彼此发送信号，并相应地改变它们的行为。了解细菌之间以及细菌与宿主之间的相互作用是生物学的一个基本挑战。细菌混合种群中细胞-细胞相互作用的分子分析是困难的。相反，某些细菌，如黄粘球菌，很容易形成生物膜，细胞在其中广泛相互作用。当饥饿时，黄原草细胞向聚集中心移动，形成新生的子实体。在子实体内，杆状细胞分化成球形的休眠孢子。对黄原菌发育过程中c信号的研究为细菌细胞如何相互作用建立了一个新的范式。c信号传导涉及CsgA，这是一种在发育细胞中产生的与细胞表面相关的蛋白质。有人提出，CsgA的蛋白水解片段在细胞之间端到端接触时起信号作用。c信号在受体细胞中诱导多种反应。它调节细胞运动、基因表达和产孢。有趣的是，对c信号的不同反应需要不同水平的CsgA， CsgA水平在发育过程中升高。因此，在发育的中后期，c信号似乎决定了事件的顺序。该项目的长期目标是确定发育基因表达响应c信号的分子机制。这项研究更广泛的影响在于，它将为细菌如何在生物膜中相互作用提供范例。所获得的见解将在环境清理、工业过程、农业实践和动物健康方面得到应用。此外，该研究还将通过培养本科生、研究生和博士后，为科学人力资源的开发做出贡献。

In nature, bacteria often exist as members of complex communities called biofilms. Cells interact within biofilms, sending signals to each other and changing their behavior in response. Understanding how bacteria interact with each other and with their hosts is a fundamental challenge in biology. Molecular analysis of cell-cell interactions in mixed populations of bacteria is difficult. In contrast, certain bacteria like Myxococcus xanthus readily form biofilms in which cells interact extensively. When starved, M. xanthus cells move to aggregation centers and construct a nascent fruiting body. Within the fruiting body, rod-shaped cells differentiate into spherical, dormant spores. Studies of C-signaling during M. xanthus development are establishing a new paradigm for how bacterial cells can interact. C-signaling involves CsgA, a protein produced in the developing cells that becomes associated with the cell surface. It has been proposed that a proteolytic fragment of CsgA serves as a signal upon end-to-end contact between cells. C-signaling induces several responses in recipient cells. It regulates cell movements, gene expression, and sporulation. Intriguingly, the different responses to C-signaling require different levels of CsgA, and the level of CsgA rises during development. Therefore, C-signaling appears to dictate the order of events during the middle to late stages of development. The long-term goal of this project is to determine the molecular mechanisms of developmental gene expression in response to C-signaling. The broader impact of the research is that it will provide paradigms for how bacteria might interact in biofilms. The insights gained will find application in environmental cleanup, industrial processes, agricultural practices, and animal health. Also, the research will contribute to the development of human resources in science through the training of undergraduates, graduate, and postdoctoral students.