Molecular mechanisms of bacterial DNA replication

遗传物质的忠实复制是所有生命繁殖的必要条件。启动这一过程需要DNA双螺旋在称为“起源”的特定位置局部解开，以便在每条亲本链上组装复制机制来合成新的DNA。尽管DNA复制具有根本的重要性，但我们对这一过程仍然没有一个全面的了解，尤其是对地球上最丰富的生命形式——细菌的情况。具体来说，细菌DNA复制的起始机制尚不完全清楚。这尤其是因为我们仍然不知道细菌复制起源中许多基本序列元素的功能。近年来，对枯草芽孢杆菌复制起源的研究在阐明细菌起源功能方面取得了重要进展。这种遗传上易于处理的生物体具有典型的细菌起源，并已被证明是研究细菌DNA复制的绝佳模型。正是在这种模式生物中，“dna三重奏”被发现。这些新的基本序列元件在细菌中广泛保守，并作为起源解绕的基础系统。然而，至关重要的是，位于dna -trios远端的基本起源序列的结构和功能仍然未知。拟建的研究项目将阐明枯草芽孢杆菌起源复制的这些区域的结构和功能。为此，我将系统地突变起源序列元件和相互作用的复制启动蛋白DnaA，并在体内和体外描述对DNA复制启动的影响。这项研究将大大提高我们对细菌复制起源的一般设置和功能的认识，并为理解细菌DNA复制的机制奠定了重要的基础。揭示细菌DNA复制起始的机制基础对于在工业应用和对抗传染病时更好地控制细菌生长至关重要。目前还没有已知的抗生素直接针对DNA复制蛋白；干扰DNA复制机制的活性或组装的化合物的开发将产生一组新的抗生素。

The faithful duplication of genetic material is imperative for the proliferation of all life. Initiating this process requires that the DNA double helix is locally unwound at specific sites termed “origins” to assemble a replicative machinery on each of the parental strands to synthesize the new DNA. Despite the fundamental importance of DNA replication, we still do not have a comprehensive picture of this process, especially not in the most abundant lifeform on earth, bacteria. Specifically, the initiation of bacterial DNA replication is not comprehensively understood. This is in particular due to the fact that we still do not know the function of many essential sequence elements in the bacterial replication origin. Important progress in elucidating bacterial origin functions was recently made by studying the origin of replication of Bacillus subtilis. This genetically tractable organism harbors an origin typical for bacteria and has proven to be an excellent model for the study of bacterial DNA replication. It was in this model organism that the “DnaA-trios” were discovered. These new essential sequence elements are widely conserved amongst bacteria and act as a basal system for origin unwinding. Critically however, the structure and function of essential origin sequences that reside distal to the DnaA-trios remain unknown.The proposed research project will elucidate the structure and function of these regions of the Bacillus subtilis origin of replication. To this end, I will systematically mutate origin sequence elements and the interacting replication initiator protein DnaA and characterize the consequences on DNA replication initiation in vivo and in vitro. The proposed study will significantly advance our knowledge about the general setup and function of bacterial replication origins and represents an essential foundation for a mechanistic understanding of bacterial DNA replication. Uncovering the mechanistic basis of DNA replication initiation in bacteria is essential for a better control of bacterial growth in industrial applications and when fighting infectious diseases. No currently known antibiotic directly targets DNA replication proteins; the development of compounds interfering with the activity or the assembly of the DNA replication machinery would yield a new group of antibiotics.