title: GEN1 from a thermophilic fungus is functionally closely similar to non-eukaryotic junction-resolving enzymes.
abstract: Processing of Holliday junctions is essential in recombination. We have identified the gene for the junction-resolving enzyme GEN1 from the thermophilic fungus Chaetomium thermophilum and expressed the N-terminal 487-amino-acid section. The protein is a nuclease that is highly selective for four-way DNA junctions, cleaving 1nt 3' to the point of strand exchange on two strands symmetrically disposed about a diagonal axis. CtGEN1 binds to DNA junctions as a discrete homodimer with nanomolar affinity. Analysis of the kinetics of cruciform cleavage shows that cleavage of the second strand occurs an order of magnitude faster than the first cleavage so as to generate a productive resolution event. All these properties are closely similar to those described for bacterial, phage and mitochondrial junction-resolving enzymes. CtGEN1 is also similar in properties to the human enzyme but lacks the problems with aggregation that currently prevent detailed analysis of the latter protein. CtGEN1 is thus an excellent enzyme with which to engage in biophysical and structural analysis of eukaryotic GEN1.
authors.affiliation: Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dow Street, Dundee DD1 5EH, UK.
authors.forename: Alasdair D J
authors.initials: ADJ
authors.lastname: Freeman
authors.affiliation: Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dow Street, Dundee DD1 5EH, UK.
authors.forename: Yijin
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dow Street, Dundee DD1 5EH, UK.
authors.forename: Anne-Cécile
authors.initials: AC
authors.lastname: Déclais
authors.affiliation: Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dow Street, Dundee DD1 5EH, UK.
authors.forename: Anton
authors.initials: A
authors.lastname: Gartner
authors.affiliation: Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dow Street, Dundee DD1 5EH, UK. Electronic address: d.m.j.lilley@dundee.ac.uk.
authors.forename: David M J
authors.initials: DMJ
authors.lastname: Lilley
mesh_terms: D000465:Algorithms; D000595:Amino Acid Sequence; D024342:Amino Acids, Acidic / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D001667:Binding, Competitive; D002597:Chaetomium / Q000201:enzymology* / Q000235:genetics; D045566:DNA, Cruciform / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D045565:Holliday Junction Resolvases / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D006868:Hydrolysis; D007700:Kinetics; D008957:Models, Genetic; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D009690:Nucleic Acid Conformation; D010802:Phylogeny; D011485:Protein Binding; D055503:Protein Multimerization; D017386:Sequence Homology, Amino Acid
chemical_list: D024342:Amino Acids, Acidic; D045566:DNA, Cruciform; D005656:Fungal Proteins; D045565:Holliday Junction Resolvases
keywords: Chaetomium thermophilum; DNA recombination and repair; FEN1; Holliday junction resolution; thermophilic proteins