RecG protein: Difference between revisions

The C-terminal domains: Domains 2 and 3 contain the characteristic motifs that identify RecG as an SF2 helicase. This part of the protein is structurally homologous with other SF2 helicases. ATP binds in the cleft between these domains and induces change in their relative orientation.

Domain’s 3 last 50 residues are forming a hook that wraps around the extended α helix of the Domain 1. This interaction provides a link between Domains 1 and 3 that is likely to be affected by nucleotide binding<ref name="structure" />.

'''INTERACTIONS WITH DNA''' [[Image:Phe.jpg | thumb ]]

Domain 1 of RecG contacts with DNA at the junction itself, indicating the specificity of the interaction with stalled replication forks. The junction is hold by the greek key motif on one side and an extended  β hairpin (residues 259–266) on another. The template strands interact with the protein grooves that are too small to accommodate DNA duplex, resulting in simultaneous split of the leading and the lagging strands. The breaking of the leading strand and the lagging strand duplexes is stabilized by the aromatic ring of Phe 204 and Tyr 208 of the protein, respectively. This mimicks base stacking of a duplex DNA structure. One of the DNA bases doesn’t contact with RecG, serving as a transient state to facilitate flipping between the duplexes during junction migration.

Additionally, the phosphodiester backbones of the duplex arms of the junction are interacting with Domain 1 and 3 of RecG. The interaction allows the formation of either a B-form (DNA) or an A-form duplex (DNA/RNA), what explains why RecG can unwind Holliday junctions (DNA) as well as R-loops (RNA)<ref name="structure" />.

'''FUNCTION''' [[Image:Manganon2.jpg | thumb ]]