Analyses of regulation mechanism of DNA replication and its evolutionary significance in cyanobacteria and chloroplast

2017 Fiscal Year Final Research Report

• Project/Area Number: 16H07418
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Single-year Grants
• Research Field: Genome biology
• Research Institution: National Institute of Genetics
• Principal Investigator: Ohbayashi Ryudo 国立遺伝学研究所, 細胞遺伝研究系, 博士研究員 (90778333)
• Project Period (FY): 2016-08-26 – 2018-03-31
• Keywords: DnaA / DNA複製 / ゲノム倍数性

Outline of Final Research Achievements

Chromosome ploidy has diversified during evolution in all of the three domains of life, bacteria, archaea, and eukaryotes. Cyanobacteria (and chloroplast) maintain multiple copies of chromosomes (genomes). Although a correlation between ploidy level and cell size has been observed in bacteria and eukaryotes, it is poorly understood how replication of multi-copy chromosomes is regulated and how ploidy level is adjusted to cell size. Here we show that only one (or a few) copy of multiple chromosomes is replicated at once in the cyanobacteria and that this restriction depends on regulation of DnaA activity. Moreover, when cell growth rate was increased or decreased at a constant temperature, DnaA level, DnaA activity, and the number of replicating chromosomes also increased or decreased, resulting in nearly constant chromosome copy number per unit cell volume.

Free Research Field

ゲノム生物学