Cell-to-Cell Transfer of Bacterial Lipoproteins

黏菌依靠细胞间的信号传导和滑动运动作为多细胞生物生存，建立子实体结构以应对饥饿。细胞-细胞信号如何组织这些发育过程仍然是一个基本的生物学问题。为了帮助了解这些过程，分离了黄粘球菌滑翔运动突变体。突变体的一个特点是它们通过细胞外互补（刺激）从含有相应野生型基因的细胞中获救。其中两种已知突变体编码脂蛋白，刺激机制涉及同源脂蛋白在细胞间的有效转移。转移不涉及细胞外分泌，而是需要供体细胞和受体细胞之间的物理接触。其中一种脂蛋白，Tgl，是极性定位的，当转移到受体细胞时，激活IV型毛滑动运动马达的组装。具体来说，Tgl的转移调节了外膜PilQ分泌素通道的组装，用于菌毛运输。一般来说，脂蛋白转移代表了一种新的细胞-细胞相互作用形式，可能在协调细胞运动，形成生物膜和/或识别不同细胞类型中发挥作用。本项目将利用分子遗传学和荧光视频显微镜的方法来了解细菌中脂蛋白转移的机制和更广泛的生物学意义。更广泛的影响本项目涉及EPSCoR州的本科生和研究生的教育和培训。本计画的内容将被纳入微生物遗传学的本科讲座和实验课，向学生展示当前的研究方法和途径。研究生将接受科学思维和分子遗传技术方面的培训。外展内容包括介绍和培训印第安人的微生物遗传学。这项拓展工作包括前往一所部落学院，招募美国原住民学生在怀俄明大学进行暑期研究实习。学生在实验室的训练是各个层次的个体之间的互动过程。这项工作将产生高质量的研究论文，项目资助的学生将在国家科学会议上发表论文。整个社会将从培养年轻科学家中受益。此外，该项目将对细胞如何在生物膜或原始发育组织等群体中相互作用提供更广泛的理解。

Intellectual MeritMyxobacteria rely on cell-cell signaling and gliding motility to live as multicellular organisms that build fruiting body structures in response to starvation. How cell-cell signaling organizes these developmental processes remains a fundamental biological question. To help understand these processes Myxococcus xanthus gliding motility mutants were isolated. A characteristic of the mutants is that they are rescued by extracellular complementation (stimulation) from cells that contain the corresponding wild type gene. Two of these known mutants encode lipoproteins and the mechanism for stimulation involves efficient cell-to-cell transfer of the cognate lipoprotein. Transfer does not involve extracellular secretion, but instead requires physical contact between donor and recipient cells. One of these lipoproteins, Tgl, is polarly localized and when transferred to a recipient cell activates the assembly of the type IV pili gliding motility motor. Specifically, Tgl transfer regulates the assembly of the outer membrane PilQ secretin channel for pilus transport. In general, lipoprotein transfer represents a novel form of cell-cell interactions that may play a role in coordinating cellular movements, forming biofilms and/or the recognition of different cell types. This project will use molecular genetic and fluorescent video microscopy methods to understand the mechanism and broader biological significance of lipoprotein transfer in bacteria. Broader ImpactsThis project involves the education and training of undergraduate and graduate students in an EPSCoR state. Elements of this project will be incorporated into undergraduate microbial genetic lecture and laboratory classes illustrating current research methods and approaches to students. Graduate students will be trained in scientific thinking and in molecular genetic techniques. An outreach component involves introducing and training Native Americans in microbial genetics. This outreach effort includes trips to a tribal college to recruit Native American students to conduct a summer research internship at the University of Wyoming. Student training in the lab is an interactive process between individuals at all levels. This work will generate high quality research papers and students supported by the project will present at national scientific meetings. Society at large will benefit from the training of young scientists. In addition, the project will provide a broader understanding of how cells interact in communities such as biofilms or in primitive developmental tissues.