Replication initiation in E. coli cell

In E. coli cell, replication of genome starts at the single origin oriC. OriC is an AT rich sequence, composed of  232 – 245 bp. At the beginning, initiator protein DnaA will recognize and bind to DnaA boxes of oriC which contains 9 bp repeats, to form a large protein – DNA complex. Among the DnaA boxes, 3 boxes R1, R2, R4 have highest affinity with DnaA. This complex contributes to melting of A-T rich DNA unwinding element (DUE) which consists of three 13 bp repeats. Continue Reading →

DNA replication origin

Replication origin is the sequences where replication started. Usually, DNA structure is the double helix, to be used as the template for replication, the duplex parental strands must be opened, by breaking hydrogen bonds between two strands. Therefore, usually, replication origin is the A-T rich sequences, as A-T base pairs contain fewer hydrogen bond than G-C base pairs. In E. coli, there is only a single origin for genome replication called OriC (232 – 245 bp). The initiator proteins bind this sequence and start replication in Continue Reading →