Initiation of DNA replication in Bacillus subtilis

重组细菌遗传物质的结构是一个复杂而动态的过程，对细菌生理学有着至关重要的影响。遗传物质的重大重组需要为DNA复制的开始创造条件，也需要帮助新的遗传物质从旧的遗传物质中分离出来。DNA重组和重塑背后的分子机制尚不清楚。我们最近发现，来自枯草芽孢杆菌的两种基本复制蛋白dna ad和DnaB表现出显著的相反的dna重塑活性。为了确定这些重塑活动是否与DNA复制和细菌生理学直接相关，我们现在正集中精力揭示支撑这些重塑活动的分子机制，并研究在细胞中限制这两种蛋白质的影响。我们的目标是解决dna的两个结构域和全长蛋白的晶体结构。诱变方法将与结构研究并行，并辅以即将到来的结构，以及超卷曲和遗传互补实验，以研究DNA重塑的机制及其对细菌生理学的意义。如果我们想要了解遗传物质是如何在一大类被称为革兰氏阳性的细菌中重组DNA复制的，那么这项研究的发现将是至关重要的。这类细菌含有重要的病原体，如金黄色葡萄球菌（导致MRSA感染），我们的发现将普遍适用于发现新的抗生素靶点。

Reorganising the architecture of the bacterial genetic material is a complicated and dynamic process with crucial consequences to bacterial physiology. Significant reorganisation of the genetic material is required to set the scene for the start of DNA replication and also to assist the separation of the new genetic material from the old one. The molecular mechanisms behind DNA reorganisation and remodelling are not understood. We have recently discovered that two essential replication proteins known as DnaD and DnaB from the bacterium Bacillus subtilis exhibit significant opposing DNA-remodelling activities. In an effort to establish whether these remodelling activities are of direct relevance to DNA replication and to bacterial physiology we are now concentrating our efforts to reveal the molecular mechanisms that underpin these remodelling activities and also to study the effects of limiting these two proteins in the cell. We are aiming to solve the crystal structures of the two domains of DnaD and also of the full-length protein. Mutagenesis methods in parallel with the structural studies but also assisted by the forth-coming structures, together with supercoiling and genetic complementation experiments will be used to study the mechanisms of DNA remodelling and their significance to bacterial physiology. The findings of this study will be crucial if we are to undertand how the genetic material is reorganised in relation to DNA replication in a large class of bacteria known as gram positives. This class of bacteria contains important pathogens like Staphylococcus aureus (responsible for MRSA infections) and our findings will be of general applicability to the discovery of new antibiotic targets.