Bacterial Cell-Wall Evolution

肽聚糖或细胞壁使细菌有一个坚硬的结构，防止它因渗透压力而破裂，并有助于细胞形状。细菌细胞的形状是高度动态的，细胞能够根据环境的不同从杆状到螺旋状再到圆形。这些细胞形状的变化可以是一种转变，可以发生在发育时间尺度上，在单个细胞周期中，也可以在细菌进化过程中成为永久性的，以响应新的环境限制。例如，我最近描述了鼻咽部细菌(这里是脑膜炎奈瑟氏菌和卡他莫拉氏菌)过去的进化。这两个物种在适应这个生态系统的过程中经历了类似的细胞形状从杆状到球状的转变。因此，可以观察到它们细胞壁结构的变化。通过采用进化的方法来检测特定的遗传学事件，就有可能揭示一些可能参与这些表型变化的蛋白质的功能。在这项研究的背景下，我们能够阐明在所有球菌中缺失的YacF(ZapD)作为细菌细胞伸长和分裂的协调者的未揭示角色。但确切的分子机制仍不清楚。*该研究计划的长期目标是通过发现新的参与者来更好地了解细胞壁的调节，并描述这些调节现象在细菌细胞周期中的重要性。在这项建议中，我们旨在深入描述YacF协调杆菌细胞周期的分子机制。我们将检验YacF在细胞伸长过程中适时抑制细胞分裂的假设。此外，我们将建立一个生物信息学工具，允许检测细菌进化过程中发生的细微变化，如氨基酸变化。在这种情况下，我们想要描述伴随着球状转变而来的突变，这些突变可能改变了蛋白质功能、蛋白质相互作用或基因调控。最后，使用与我们在NeisSeraceae或Moraxellaceae家族中使用的类似的进化类型的方法，我们将通过寻找自然的形态变异(这里是Simonsiella muelleri)来揭示与细胞壁调节有关的其他成员。*我们配备了从生物信息学、基因组学、分子生物学到微生物生态学的多学科专业知识，旨在了解细菌细胞壁进化背后的机制和这种变化的原因。对这些机制的更好理解最终将有助于改进工业上重要的细菌菌株或开发可应用于农业、生物技术和医学等众多领域的细菌种群控制的新方法。

The peptidoglycan or cell wall gives the bacteria a rigid structure, protects it from bursting due to osmotic pressure and contributes to cell shape. Bacterial cell shape is highly dynamic and cells are able to change from rod to spiral to round morphologies depending on their environment. These cell shape changes can be a transition that can happen on the developmental time scale, during a single cell cycle or it can become permanent through the course of bacterial evolution to respond to new environmental constraints. For example, I recently described the past evolution of nasopharyngeal bacteria (herein Neisseria meningitidis and Moraxella catarrhalis). Both species have undergone a similar cell-shape transition from rod to coccus during their adaptation to this ecosystem. As a consequence, changes in the structure of their cell-wall could be observed. By taking an evolutionary approach to detect specific genetics events, it is possible to expose the function of some proteins that could be involved in these phenotypic alterations. In the context of this study, we were able to shed light on an unrevealed role of YacF (ZapD), deleted in all cocci, as a coordinator of bacterial cell elongation and division. But the precise molecular mechanism is still unknown. ***The long-term goal of the research program is to better understand the regulation of the cell-wall by discovering new players and describe the importance of these regulation phenomena in the bacterial cell cycle. In this proposal, we aim at describing in depth the molecular mechanisms behind YacF coordination of the cell cycle in bacilli. We will test the hypothesis that YacF is timely inhibiting cell division during the course of cellular elongation. In addition, we will build a bioinformatics tool that will allow the detection of subtle modifications such as amino-acids change that happen during bacterial evolution. In this case, we want to describe mutations concomitant with the coccoid transition that could have changed protein function, protein-protein interaction or genes regulation. Finally, using similar evolutionary type of methods as we used in the Neisseriaceae or Moraxellaceae family, we will reveal other players implicated in the cell-wall regulation by searching for natural morphological aberration (herein Simonsiella muelleri). ***Equipped with multi-disciplinary expertise from bioinformatics, genomics and molecular biology to microbial ecology, we aim at understanding the mechanisms behind bacterial cell-wall evolution and the reasons of such changes. A better understanding of these mechanisms will ultimately allow improvement of industrially important bacterial strains or the development of new approaches towards bacterial population control that could be applicable to numerous fields such as agriculture, biotechnology and medicine.********* **