The cell division interactome of Enterococcus faecalis

粪肠球菌（Enterococcus faecalis, Ef）是一种耐抗生素的“超级细菌”，广泛分布于自然界，定植于多种哺乳动物、鸟类、爬行动物、昆虫等生物体内。Ef作为一种兽医和人类病原体具有重要的社会意义，有可能引起严重疾病并向其他细菌传播严重的抗生素耐药性。Ef细胞生存、生长和扩散的一个重要组成部分是它的分裂能力。细胞分裂是一个复杂的分子过程，首先在细胞中部形成一个FtsZ蛋白环，然后是一系列不同的蛋白质相互作用形成分裂体（细胞分裂相互作用组）。在某些细菌中，FtsZ在细胞中间的位置是由名为MinC、MinD和MinE的蛋白质指导的。一些被归类为革兰氏阳性（Gm+）的细菌缺乏MinE，而是拥有一种名为DivIVA的保守蛋白质。其他Gm+细菌，如Ef，缺乏任何Min蛋白，但保留DivIVA同源物。因此，不同的细菌在细胞分裂过程中使用不同的蛋白质。利用Ef作为模型微生物研究Gm+球菌细胞分裂，我们发现了一个新的与DivIVA结合并参与Ef细胞分裂的保守蛋白MLJD1。这种基因在Ef中的破坏会导致细胞死亡。我们还确定了DivIVA功能所需的重要氨基酸和结构。在我们目前的研究中，我们将通过微生物学、显微镜学、分子、遗传学和生化等方法进一步研究Ef分裂体/相互作用体。我们将充分定义至少11种Ef细胞分裂蛋白之间的各种相互作用，从而开发出第一个高质量的Ef细胞分裂/相互作用图谱。我们将对DivIVAEf -MLJD1相互作用的基础、MLJD1的结构以及这些蛋白与其他各种细胞分裂蛋白的相互作用产生新的见解。对Ef分裂体的研究，以及与之相关的新蛋白质，不仅将提供关于这种重要生物如何分裂的关键信息，而且可能找到帮助我们对抗这种细菌和其他抗生素耐药细菌的途径。

Enterococcus faecalis (Ef), a bacterium which is an antibiotic resistant "superbug", is widely distributed in nature, colonizing a variety of mammals, birds, reptiles, insects and other organisms. Ef has important societal relevance as a veterinary and human pathogen with the potential to cause serious disease and to spread serious antibiotic resistance to other bacteria. An essential component of Ef cell viability, growth and spread is its ability to divide. Cell division is a complex molecular process initiated by the formation of an FtsZ protein ring at the mid-cell site followed by a cascade of different proteins which interact to form the divisome (cell division interactome). In certain bacteria, FtsZ placement at the mid-cell is directed by proteins named MinC, MinD and MinE. Some bacteria, classified as Gram-positive (Gm+), lack MinE and instead possess a conserved protein called DivIVA. Other Gm+ bacteria, such as Ef, lack any Min proteins but retain DivIVA homologues. Thus, different proteins are used in the cell division process in different bacteria. Using Ef as a model microorganism to study Gm+ coccal cell division, we identified a new conserved protein, MLJD1, which binds DivIVA and which participates in Ef cell division. Disruption of this gene in Ef causes cell death. We also identified important amino acids and structures required for DivIVA functionality. In our present research, we will further investigate the Ef divisome/interactome through microbiological, microscopy, molecular, genetic and biochemical approaches. We will fully define the various interactions between at least 11 Ef cell division proteins, thereby developing the first high quality divisome/interactome map for Ef. We will produce novel insight regarding the basis of the DivIVAEf -MLJD1 interaction, the structure of MLJD1, and the interaction of these proteins with the full range of other cell division proteins. Research on the Ef divisome, and the novel proteins associated with it will produce critical information not only on how this important organism divides, but may identify avenues that may help us to combat this and other antibiotic resistant bacteria.