大肠杆菌（Escherichia coli）染色体复制起始是个严格调控的细胞过程。首先，DnaA在复制原点（oriC）打开双链DNA，之后，DnaB解旋酶、SSB和DNA 聚合酶III组装后便启动复制。真核细胞也有相似的复制起始调控机制。我们发现yfiF基因的删除引起复制起始的推迟；过表达YbfE蛋白导致复制起始的提早发生；软件分析发现YfiF蛋白预测功能是个RNA甲基转移酶。本项目以揭示以上生命现象背后机制为目标，确定YfiF蛋白的功能域；探索YfiF与核糖体的相互作用机制；检测YfiF是否是个RNA甲基转移酶；探明YfiF蛋白介导的复制起始调控机制，鉴定YfiF生物学功能。 染色体异常复制会降低基因组的稳定性，并由此引发细胞癌变或发育缺陷。所以，本项研究不仅在生命科学基础研究中具重要意义，而且在医学研究和临床应用方面也具有借鉴和指导作用。

Initiation of chromosomal replication is tightly regulated in Escherichia coli.First, the DnaA protein unwinds the double-stranded DNA at the replication origin (oriC), and then DnaB helicase,SSB,DNA PolIII are recruited at the open site and start replication. The analogous control of replication initiation has been found in Eukaryotic cells. We found that deletion of the yfiF gene delayed initition of replication; on contrast,overexpresion of the YfiF protein led to an early initition of replication. However, the mechanisms behind the findings have remained unclear. The project has been designed: to determine functional domains of YfiF; to investigate if YfiF is a ribosome-associated protein and if YfiF is a RNA methytransferase; to understand what the functions of YfiF are. Finally we aim to characterize YfiF-mediated control of initiation of replication using genetic and molecular biological methods. Uncontrolled replication leads to different diseases including cancers as a result of genome instability. Therefore, the project will shed light on the regulation of DNA replication of both normal and cancer cells.