A conserved nuclease domain in the archaeal Holliday junction resolving enzyme Hjc.
Holliday junction resolving enzymes are ubiquitous proteins that function in the pathway of homologous recombination, catalyzing the rearrangement and repair of DNA. They are metal ion-dependent endonucleases with strong structural specificity for branched DNA species. Whereas the eukaryotic nuclear enzyme remains unknown, an archaeal Holliday junction resolving enzyme, Hjc, has recently been identified. We demonstrate that Hjc manipulates the global structure of the Holliday junction into a 2-fold symmetric X shape, with local disruption of base pairing around the point of cleavage that occurs in a region of duplex DNA 3' to the point of strand exchange. Primary and secondary structural analysis reveals the presence of a conserved catalytic metal ion binding domain in Hjc that has been identified previously in several restriction enzymes. The roles of catalytic residues conserved within this domain have been confirmed by site-directed mutagenesis. This is the first example of this domain in an archaeal enzyme of known function as well as the first in a Holliday junction resolving enzyme.
Department of Biochemistry, University of Dundee.
M
M
Kvaratskhelia
B N
BN
Wardleworth
D G
DG
Norman
M F
MF
White
D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry*; D020134:Catalytic Domain; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004706:Endodeoxyribonucleases / Q000737:chemistry* / Q000235:genetics; D004926:Escherichia coli / Q000378:metabolism; D045565:Holliday Junction Resolvases; D007700:Kinetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000378:metabolism; D011196:Potassium Permanganate / Q000378:metabolism; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000378:metabolism; D011995:Recombination, Genetic; D017386:Sequence Homology, Amino Acid; D016944:Sulfolobus / Q000201:enzymology; D013997:Time Factors
D019843:Archaeal Proteins; D009841:Oligonucleotides; D011994:Recombinant Proteins; D011196:Potassium Permanganate; D004706:Endodeoxyribonucleases; D045565:Holliday Junction Resolvases