RecA-like domain of Escherichia coli bacteriophage T7 Gp4D helicase
This family includes the RecA-like domain of the Gp4D fragment of the Gene4 helicase-primase (Gp4) from bacteriophage T7. Gp4D (residues 241-566) is the minimal fragment of the Gp4 that forms hexameric rings, it contains the helicase domain and the linker connecting the helicase and primase domains. Helicases are ring-shaped oligomeric enzymes that unwind DNA at the replication fork; they couple NTP hydrolysis to the unwinding of nucleic acid duplexes into their component strands. This family belongs to the RecA-like NTPase superfamily which includes the NTP binding domain of F1 and V1 H(+)ATPases, DnaB and related helicases as well as bacterial RecA and related eukaryotic and archaeal recombinases. The RecA-like NTPase family also includes bacterial conjugation proteins and related DNA transfer proteins involved in type II and type IV secretion.