Investigation of a soluble DNA translocase

在细胞分裂发生之前，细胞必须确保复制的染色体彼此完全分离。虽然目前尚不清楚真核细胞如何防止分离延迟的染色体被困在分裂间隔内，但已经很明显的是，细菌含有专门的DNA转位酶，如果细胞在分离完成之前发生分裂，这种转位酶可以通过闭合的膜运输DNA。以模式细菌枯草芽孢杆菌为例，我们最近发现，两种DNA转位酶在两个不同的步骤中执行这一任务。新发现的SFTA DNA转位酶在隔膜关闭期间将DNA移走，而膜蛋白SpoIIIE通过其在关闭的隔膜内形成的通道泵送DNA。有趣的是，我们发现SFTA是完全可溶的，因此是迄今为止描述的第一个非膜结合的DNA转位酶。我们计划研究蛋白质如何与DNA结合，这是一个任何DNA转位酶都没有回答的问题。SFTA在溶液中形成六聚体，它必须以某种方式为DNA易位打开。我们还将研究SFTA的DNA易位马达是如何在分子水平上工作的。我们还将通过确定SFTA的直接结合伙伴来分析SFTA是如何被招募到本身以膜为锚定的部门机制中的。

Cells must ensure that duplicated chromosomes are fully separated from each other before cell division occurs. While it is still unclear how eukaryotic cells prevent the entrapment of segregation-delayed chromosomes within the division septum, it has become clear that bacteria contain dedicated DNA translocases that transport DNA through closed membranes if cell division occurs before segregation has been completed. In the case of the model bacterium Bacillus subtilis, we have recently discovered that two DNA translocases perform this task at two different steps. The newly identified SftA DNA translocase moves DNA away during the closure of the division septum, while the membrane protein SpoIIIE pumps DNA through a channel it forms within the closed septum. Interestingly, we found that SftA is fully soluble, and is thus the first non-membrane bound DNA translocase described so far. We plan to investigate how the protein binds to DNA, a question that has not been answered for any DNA translocase. SftA forms hexamers in solution, which somehow must open up for DNA translocation. We will also investigate how the DNA translocation motor of SftA works at a molecular level. We will also analyse how SftA is recruited to the division machinery, which itself is membrane-anchored, through the identification of direct binding partners of SftA.