In bacteria, what protein recognizes the origin of replication (oriC) and initiates replication?

• A. DnaB
• B. DnaC
• C. DnaA
• D. Primase

Answer: (C)

The question is about how bacterial DNA replication starts at the origin. The initiator protein that recognizes oriC and kicks off replication is DnaA. DnaA binds to multiple specific sites within oriC, and in its ATP-bound form promotes opening of the AT-rich region, helping to melt the DNA and create a ready replication fork. This initial opening then allows loading of the helicase complex to unwind the DNA further; in bacteria, the helicase is DnaB and it gets loaded onto the DNA by the helicase loader DnaC. Once the helicase is in place and the strands are separated, primase (DnaG) synthesizes RNA primers to start DNA synthesis. So DnaA is the key initiator that recognizes oriC and begins replication, while the other proteins handle unwinding and primer formation needed for the process to proceed.