RecG protein: Difference between revisions

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'''RecG''' [[Image:RecG.jpg | thumb ]]

The RecG protein ~~of Escherichia coli is~~ a Superfamily 2 (SF2) branched-DNA-specific helicase which promotes rescue of damaged replication forks by ~~catalysing~~ their unwinding and conversion to Holliday junctions. A single RecG monomer unwinds two DNA duplexes; the leading strand duplex and the lagging strand duplex and then ~~reanneal~~ the parental and the newly synthetized strands. This mechanism of repair is ATP-dependent and does not require DNA double strand break. RecG works synergistically with the RuvABC repair system<ref name="structure">Singleton, M. R., Scaife, S. & Wigley, D. B. Structural analysis of DNA replication fork reversal by RecG. Cell 107, 79–89 (2001)</ref>,<ref>Rudolph, C. J., Upton, A. L., Briggs, G. S. & Lloyd, R. G. Is RecG a general guardian of the bacterial genome? DNA Repair 9, 210–223 (2010)</ref>.

The '''RecG''' protein of ''Escherichia coli'' is a Superfamily 2 (SF2) branched-DNA-specific helicase which promotes rescue of damaged replication forks by catalyzing their unwinding and conversion to Holliday junctions. A single RecG monomer unwinds two DNA duplexes; the leading strand duplex and the lagging strand duplex and then re-anneal the parental and the newly synthetized strands. This mechanism of repair is ATP-dependent and does not require DNA double strand break. RecG works synergistically with the RuvABC repair system<ref name="structure">Singleton, M. R., Scaife, S. & Wigley, D. B. Structural analysis of DNA replication fork reversal by RecG. Cell 107, 79–89 (2001)</ref>,<ref>Rudolph, C. J., Upton, A. L., Briggs, G. S. & Lloyd, R. G. Is RecG a general guardian of the bacterial genome? DNA Repair 9, 210–223 (2010)</ref>.

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'''RELEVANCE'''

The RecG of Escherichia coli is needed for normal levels of recombination and for repair of damaged DNA. RecG homologues are found in most bacterial species<ref>Sharples, G. J., Ingleston, S. M. & Lloyd, R. G. Holliday junction processing in bacteria: Insights from the evolutionary conservation of RuvABC, RecG, and RusA. Journal of Bacteriology 181, 5543–5550 (1999)</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>. The mutants' phenotype is very mild and the dramatic increase in sensitivity to DNA damaging agents observed when recG null alleles are combined with ruv mutations inactivating the RuvABC Holliday junction resolvase<ref>Pang, Q., Hays, J. B. & Rajagopal, I. Two cDNAs from the plant Arabidopsis thaliana that partially restore recombination proficiency and DNA-damage resistance to E.coli mutants lacking recombination-intermediate-resolution activities. Nucleic Acids Research21,1647–1653 (1993)</ref>. These findings suggest that RecG and RuvABC are part of two overlapping pathways to overcome damage to DNA via a recombination mechanism.

The RecG of ''Escherichia coli'' is needed for normal levels of recombination and for repair of damaged DNA. RecG homologues are found in most bacterial species<ref>Sharples, G. J., Ingleston, S. M. & Lloyd, R. G. Holliday junction processing in bacteria: Insights from the evolutionary conservation of RuvABC, RecG, and RusA. Journal of Bacteriology 181, 5543–5550 (1999)</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>. The mutants' phenotype is very mild and the dramatic increase in sensitivity to DNA damaging agents observed when recG null alleles are combined with ruv mutations inactivating the RuvABC Holliday junction resolvase<ref>Pang, Q., Hays, J. B. & Rajagopal, I. Two cDNAs from the plant Arabidopsis thaliana that partially restore recombination proficiency and DNA-damage resistance to E.coli mutants lacking recombination-intermediate-resolution activities. Nucleic Acids Research21,1647–1653 (1993)</ref>. These findings suggest that RecG and RuvABC are part of two overlapping pathways to overcome damage to DNA via a recombination mechanism.

Despite the important role of RecG in bacteria, there are no known homologs in other organisms, at least at the sequence level. However, phage T4 protein UvsW can complement a recG defect in E. coli, showing that it is a functional homolog of RecG<ref>Dudas, K. C. & Kreuzer, K. N. UvsW protein regulates bacteriophage T4 origin-dependent replication by unwinding R-loops. Molecular and Cellular Biology21,2706–2715 (2001)</ref>. The conservation of function rather than sequence raises the possibility that there may be proteins with RecG-like functions in other organisms. Indeed, it has been suggested that a number of helicases (e.g., Werner's, BLM, and Sgs1) may play a role in the recovery of stalled replication forks in eukaryotes<ref>Frei, C. & Gasser, S. M. RecQ-like helicases: the DNA replication checkpoint connection. Journal of cell science113 ( Pt 1,2641–2646 (2000)</ref>.

'''3D Structures of RecG'''

Updated on {{REVISIONDAY2}}-{{MONTHNAME|{{REVISIONMONTH}}}}-{{REVISIONYEAR}}

[[1gm5]] - RecG + DNA - ''Escherichia coli''<br />

RecG protein: Difference between revisions

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 '''RecG''' [[Image:RecG.jpg | thumb ]]
-The RecG protein of Escherichia coli is a Superfamily 2 (SF2) branched-DNA-specific helicase which promotes rescue of damaged replication forks by catalysing their unwinding and conversion to Holliday junctions. A single RecG monomer unwinds two DNA duplexes; the leading strand duplex and the lagging strand duplex and then reanneal the parental and the newly synthetized strands. This mechanism of repair is ATP-dependent and does not require DNA double strand break. RecG works synergistically with the RuvABC repair system<ref name="structure">Singleton, M. R., Scaife, S. & Wigley, D. B. Structural analysis of DNA replication fork reversal by RecG. Cell 107, 79–89 (2001)</ref>,<ref>Rudolph, C. J., Upton, A. L., Briggs, G. S. & Lloyd, R. G. Is RecG a general guardian of the bacterial genome? DNA Repair 9, 210–223 (2010)</ref>.
+The '''RecG''' protein of ''Escherichia coli'' is a Superfamily 2 (SF2) branched-DNA-specific helicase which promotes rescue of damaged replication forks by catalyzing their unwinding and conversion to Holliday junctions. A single RecG monomer unwinds two DNA duplexes; the leading strand duplex and the lagging strand duplex and then re-anneal the parental and the newly synthetized strands. This mechanism of repair is ATP-dependent and does not require DNA double strand break. RecG works synergistically with the RuvABC repair system<ref name="structure">Singleton, M. R., Scaife, S. & Wigley, D. B. Structural analysis of DNA replication fork reversal by RecG. Cell 107, 79–89 (2001)</ref>,<ref>Rudolph, C. J., Upton, A. L., Briggs, G. S. & Lloyd, R. G. Is RecG a general guardian of the bacterial genome? DNA Repair 9, 210–223 (2010)</ref>.
@@ Line 35: / Line 35: @@
 '''RELEVANCE'''
-The RecG of Escherichia coli is needed for normal levels of recombination and for repair of damaged DNA. RecG homologues are found in most bacterial species<ref>Sharples, G. J., Ingleston, S. M. & Lloyd, R. G. Holliday junction processing in bacteria: Insights from the evolutionary conservation of RuvABC, RecG, and RusA. Journal of Bacteriology 181, 5543–5550 (1999)</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>. The mutants' phenotype is very mild and the dramatic increase in sensitivity to DNA damaging agents observed when recG null alleles are combined with ruv mutations inactivating the RuvABC Holliday junction resolvase<ref>Pang, Q., Hays, J. B. & Rajagopal, I. Two cDNAs from the plant Arabidopsis thaliana that partially restore recombination proficiency and DNA-damage resistance to E.coli mutants lacking recombination-intermediate-resolution activities. Nucleic Acids Research21,1647–1653 (1993)</ref>. These findings suggest that  RecG and RuvABC are part of two overlapping pathways to overcome damage to DNA via a recombination mechanism.
+The RecG of ''Escherichia coli'' is needed for normal levels of recombination and for repair of damaged DNA. RecG homologues are found in most bacterial species<ref>Sharples, G. J., Ingleston, S. M. & Lloyd, R. G. Holliday junction processing in bacteria: Insights from the evolutionary conservation of RuvABC, RecG, and RusA. Journal of Bacteriology 181, 5543–5550 (1999)</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>. The mutants' phenotype is very mild and the dramatic increase in sensitivity to DNA damaging agents observed when recG null alleles are combined with ruv mutations inactivating the RuvABC Holliday junction resolvase<ref>Pang, Q., Hays, J. B. & Rajagopal, I. Two cDNAs from the plant Arabidopsis thaliana that partially restore recombination proficiency and DNA-damage resistance to E.coli mutants lacking recombination-intermediate-resolution activities. Nucleic Acids Research21,1647–1653 (1993)</ref>. These findings suggest that  RecG and RuvABC are part of two overlapping pathways to overcome damage to DNA via a recombination mechanism.
 Despite the important role of RecG in bacteria, there are no known homologs in other organisms, at least at the sequence level. However, phage T4 protein UvsW can complement a recG defect in E. coli, showing that it is a functional homolog of RecG<ref>Dudas, K. C. & Kreuzer, K. N. UvsW protein regulates bacteriophage T4 origin-dependent replication by unwinding R-loops. Molecular and Cellular Biology21,2706–2715 (2001)</ref>. The conservation of function rather than sequence raises the possibility that there may be proteins with RecG-like functions in other organisms. Indeed, it has been suggested that a number of helicases (e.g., Werner's, BLM, and Sgs1) may play a role in the recovery of stalled replication forks in eukaryotes<ref>Frei, C. & Gasser, S. M. RecQ-like helicases: the DNA replication checkpoint connection. Journal of cell science113 ( Pt 1,2641–2646 (2000)</ref>.
+'''3D Structures of RecG'''
+Updated on {{REVISIONDAY2}}-{{MONTHNAME|{{REVISIONMONTH}}}}-{{REVISIONYEAR}}
+[[1gm5]] - RecG + DNA - ''Escherichia coli''<br />