Question

Explain the difference between protein priming and prime-realign mechanisms of replication initation.

Answer 1

DNA primer is a small stretch of DNA that which is required for the replication initiation by DNA polymerase. In protein priming, the DNA replication involves only a single unit DNA polymerase as well as priming of DNA. For example, the DNA pol of Phage phi29 in Bacillus subtilis which has three functions including DNA synthesis, primer terminal protein and exonuclease activity.

Prime-realign mechanisms of replication initiation uses the repeated nucleotide sequence at the 3' end of the template. The pppCpG_OH binds to the +2 position of the template which is then act as a primer to initatiate replication. After the initiation, the newly synthesised RNA strand is realigned, so that the newly synthesized strand starts from +1 position. This mechanism is called as priming and realigning.