RecG protein: Difference between revisions

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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>Singleton, M. R., Scaife, S. & Wigley, D. B. Structural analysis of DNA replication fork reversal by RecG. Cell 107, 79–89 (2001)</ref>.

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>Singleton, M. R., Scaife, S. & Wigley, D. B. Structural analysis of DNA replication fork reversal by RecG. Cell 107, 79–89 (2001)</ref>. Strains carrying mutations in this gene show reduced recombination in conjugational crosses and increased sensitivity to UV, mitomycin C and ionizing radiation<ref>Storm, P. K., Hoekstra, W. P. M., De Haan, P. G. & Verhoef, C. Genetic recombination in Escherichia coli. IV. Isolation and characterization of recombinaion-deficient mutants of Escherichia coli K12. Mutation Research - Fundamental and Molecular Mechanisms of Mutagenesis13,9–17 (1971)</ref>,<ref>Lloyd, R. G. & Buckman, C. Genetic analysis of the recG locus of Escherichia coli K-12 and of its role in recombination and DNA repair. Journal of bacteriology173,1004–1011 (1991)</ref>,<ref>Kalman, M., Murphy, H. & Cashel, M. The nucleotide sequence of recG, the distal spo operon gene in Escherichia coli K-12. Gene110,95–99 (1992)</ref>.

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RecG protein: Difference between revisions

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 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>Singleton, M. R., Scaife, S. & Wigley, D. B. Structural analysis of DNA replication fork reversal by RecG. Cell 107, 79–89 (2001)</ref>.
+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>Singleton, M. R., Scaife, S. & Wigley, D. B. Structural analysis of DNA replication fork reversal by RecG. Cell 107, 79–89 (2001)</ref>. Strains carrying mutations in this gene show reduced recombination in conjugational crosses and increased sensitivity to UV, mitomycin C and ionizing radiation<ref>Storm, P. K., Hoekstra, W. P. M., De Haan, P. G. & Verhoef, C. Genetic recombination in Escherichia coli. IV. Isolation and characterization of recombinaion-deficient mutants of Escherichia coli K12. Mutation Research - Fundamental and Molecular Mechanisms of Mutagenesis13,9–17 (1971)</ref>,<ref>Lloyd, R. G. & Buckman, C. Genetic analysis of the recG locus of Escherichia coli K-12 and of its role in recombination and DNA repair. Journal of bacteriology173,1004–1011 (1991)</ref>,<ref>Kalman, M., Murphy, H. & Cashel, M. The nucleotide sequence of recG, the distal spo operon gene in Escherichia coli K-12. Gene110,95–99 (1992)</ref>.
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