Chromosome DNA is replicated once per cell cycle. DNA replication starts from many origins spread over chromosomes and replication forks are established. Replication forks often face and pause at the obstacles on chromosomes, such as DNA damage and tightly bound proteins. The proper pausing of replication forks at barriers on chromosomes is important for genome integrity. However, the detailed mechanism underlying this process has not been well elucidated. We successfully reconstituted fork-pausing reactions from purified yeast proteins on templates that had binding sites for the proteins; the forks paused specifically at the protein-bound sites. Moreover, although the replicative CMG helicase alone unwound the protein-bound templates, the unwinding of the protein-bound site was impeded by the presence of a major leading-strand DNA polymerase, Polε. This suggests that Polε modulates CMG to pause at these sites.

Figure: DNA polymerase ε (Polε) impedes the replicative helicase (CMG) at the site that the protein (LacI) binds and eventually DNA replication stalls. In the absence of Polε, CMG unwinds double-stranded DNA even at the site and thus replication continues.

Press release

Press release (In Japanese only)

The deposition pattern of plant cell walls influences the nature of plant body, such as size, shape, and stiffness. In xylem vessels, cell wall deposition is locally inhibited to form pits, which are tiny caves in cell walls that allow waters move through xylem vessels. Our research group revealed the regulatory mechanism of the pit formation by combining the genetic approach and mathematical approach known as “reaction-diffusion system”. The knowledge obtained in our research may contribute to developing new plants of modified size and stiffness by artificially regulating the deposition pattern of cell walls.

Figure:
(A) Water transport in plants
(B) ROP11 activity determines the amount of pits

New assistant professor joins NIG as of October 1, 2018.

TANIZAWA, Yasuhiro: Genome Informatics Laboratory • Nakamura Group