バクテリアにおいて染色体のコピー数を自在に制御できる系の構築を目指し, 倍数体の高度好熱菌を対象としてDNA複製開始機構の解明を試みた。複製開始に必須の領域を特定するため, ゲノムDNAライブラリーから自立的複製能を有するクローンのスクリーニング, 染色体から環状DNAとしてコピーアウトした領域の複製能の検証を多数行ったが, 未だ複製開始領域の特定には至っていない。一方, 巨大な環状プラスミドの複製には, プラスミド上で真逆の位置にある2つの領域が必要であることを明らかにした。染色体の場合も離れて存在する複数の領域が複製開始に関わる可能性が考えられ, 異なるアプローチを試みる必要が出てきた。
DNA replication initiation of an extremely thermophilic bacterium harboring multiple chromosomal copies in a cell was studied, aiming to build a chromosome copy number control system in bacteria. To identify an essential region for replication initiation on the chromosome, screening for a genomic DNA clone exhibiting autonomous replication ability was performed and the abilities of larger regions copied out of the chromosome were also examined. However, the essential region for replication initiation has not yet been identified. In this study, we have unveiled that the essential part for megaplasmid pTT27 replication consists of two regions positioned distantly on the plasmid. It implies that chromosomal replication initiation might also require distantly-positioned multiple regions on the chromosome. In this case, we must try different approaches to identify the essential region for chromosomal replication initiation.
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