RecG_wedge_OBF: A subfamily of OB folds corresponding to the OB fold found in the N-terminal (wedge) domain of Escherichia coli RecG. RecG is a branched-DNA-specific helicase, which catalyzes the interconversion of a DNA replication fork to a four-stranded (Holliday) junction in vivo and in vitro. This interconversion provides a route to repair stalled forks. The RecG monomer contains three domains. The N-terminal domain is named for its wedge structure, and may provide the specificity of RecG for binding branched-DNA structures. During the reversal of fork to Holliday junction, the wedge domain is fixed at the junction of the fork where the leading and lagging strand duplex arms meet, and is thought to promote the unwinding of the nascent leading and lagging strands. In order to form the Holliday junction, these nascent strands would be annealed, and the parental strands reannealed. The wedge domain may also be a processivity factor of RecG on these branched chain substrates.
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