This is the N-terminal domain of the Rolling Circle Replication Initiator Protein (Rep) from Geobacillus stearothermophilus. This protein acts on plasmids from family pT181 to initiate replication, recruit a helicase to the site of initiation and terminate replication after DNA synthesis. These proteins possess a unique active site and a catalytically essential metal ion is bound in a distinct manner from other rolling circle Reps [1].

1: Structures of replication initiation proteins from staphylococcal antibiotic resistance plasmids reveal protein asymmetry and flexibility are necessary for replication. Carr SB, Phillips SE, Thomas CD; Nucleic Acids Res. 2016;44:2417-2428. PMID:26792891