In prokaryotes, which enzyme removes RNA primers from Okazaki fragments?

In prokaryotes, DNA polymerase I removes RNA primers from Okazaki fragments. Its 5′-to-3′ exonuclease activity removes the RNA primer, while its polymerase activity replaces the removed ribonucleotides with DNA.

This work is part of Okazaki-fragment maturation on the lagging strand. Because DNA polymerases synthesize only in the 5′-to-3′ direction, the lagging strand is built discontinuously in short sections. Each section begins with an RNA primer made by primase. In bacteria such as Escherichia coli, DNA polymerase I can remove the primer and fill the resulting gap in a coordinated process called nick translation.

DNA polymerase III is the main replicative polymerase in many bacteria, but it generally does not perform the complete primer-removal job. Primase makes the RNA primers, and DNA ligase seals the remaining nick after DNA polymerase I has filled the gap. RNase H can also participate in primer degradation, depending on the organism and replication context. The exact division of labor varies among prokaryotes, but DNA polymerase I is the canonical quiz answer for bacterial Okazaki-primer removal.