Research Area

 The replication of chromosomal DNA is indispensable for cell division, growth, and reproduction. The process of chromosomal DNA replication is well conserved among organisms, from bacteria to human. Interaction of specific trans-acting proteins including an initiator with unique cis-acting DNA sequences (replicator or origin of replication) results in unwinding of duplex DNA by DNA helicase. Then, the primer synthesized by DNA primase is elongated by DNA polymerase. The precise timing and highly controlled frequency of chromosomal initiation have suggested the existence of positive and negative regulators acting at the initiation process. However, those regulators remain to be identified.

Taking the advantage of relatively abundant information concerning biochemical, physiological, and genetic aspects of E. coli chromosomal replication, we are exploring the mechanism and regulation of chromosomal initiation at oriC (origin of chromosomal replication). By using the tools of protein-protein and protein-DNA interaction, and genetic screening, we are identifying novel factors, which are expected to participate in the initiation control. We are also investigating regulatory factors and their molecular mechanisms for the expression of genes, whose functions are required for the regulation of chromosomal initiation

Research

1. Interaction of replication initiation proteins (DnaA, HU, IHF, DnaB, DnaC) and regulators (SeqA, IciA) on the chromosomal origin, oriC.

2. Molecular mechanism on the hemimethylated replication origin for chromosomal regulation.

3. Identification and molecular mechanism of novel factors involved in the control of chromosomal replication initiation.

4. Identification and molecular mechanism of transcriptional modulators for the expression of genes involved in chromosomal regulation