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1hh1
From Proteopedia
THE STRUCTURE OF HJC, A HOLLIDAY JUNCTION RESOLVING ENZYME FROM SULFOLOBUS SOLFATARICUS
Structural highlights
FunctionHJC_SACS2 A structure-specific endonuclease that resolves Holliday junction (HJ) intermediates during genetic recombination; may have some degree of sequence preference in a mobile junction. Cleaves 4-way DNA junctions introducing paired nicks in opposing strands, leaving a 5'-terminal phosphate and a 3'-terminal hydroxyl group that are ligated to produce recombinant products. Can cleave all 4 strands 3 bases 3' of the junction center. Cleaves both mobile and immobile junctions. Modifies the structure of the 4-way DNA junction, a model Holliday junction structure. The protein forms multiple complexes with 4-way DNA, suggesting more than 1 homodimer can bind to each junction.[1] [2] [3] [4] [5] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe 2.15-A structure of Hjc, a Holliday junction-resolving enzyme from the archaeon Sulfolobus solfataricus, reveals extensive structural homology with a superfamily of nucleases that includes type II restriction enzymes. Hjc is a dimer with a large DNA-binding surface consisting of numerous basic residues surrounding the metal-binding residues of the active sites. Residues critical for catalysis, identified on the basis of sequence comparisons and site-directed mutagenesis studies, are clustered to produce two active sites in the dimer, about 29 A apart, consistent with the requirement for the introduction of paired nicks in opposing strands of the four-way DNA junction substrate. Hjc displays similarity to the restriction endonucleases in the way its specific DNA-cutting pattern is determined but uses a different arrangement of nuclease subunits. Further structural similarity to a broad group of metal/phosphate-binding proteins, including conservation of active-site location, is observed. A high degree of conservation of surface electrostatic character is observed between Hjc and T4-phage endonuclease VII despite a complete lack of structural homology. A model of the Hjc-Holliday junction complex is proposed, based on the available functional and structural data. Structure of Hjc, a Holliday junction resolvase, from Sulfolobus solfataricus.,Bond CS, Kvaratskhelia M, Richard D, White MF, Hunter WN Proc Natl Acad Sci U S A. 2001 May 8;98(10):5509-14. Epub 2001 May 1. PMID:11331763[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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