title: A SRS2 homolog from Arabidopsis thaliana disrupts recombinogenic DNA intermediates and facilitates single strand annealing.
abstract: Genetic and biochemical analyses of SRS2 homologs in fungi indicate a function in the processing of homologous recombination (HR) intermediates. To date, no SRS2 homologs have been described and analyzed in higher eukaryotes. Here, we report the first biochemical characterization of an SRS2 homolog from a multicellular eukaryote, the plant Arabidopsis thaliana. We studied the basic properties of AtSRS2 and were able to show that it is a functional 3'- to 5'-helicase. Furthermore, we characterized its biochemical function on recombinogenic intermediates and were able to show the unwinding of nicked Holliday junctions (HJs) and partial HJs (PX junctions). For the first time, we demonstrated strand annealing activity for an SRS2 homolog and characterized its strand pairing activity in detail. Our results indicate that AtSRS2 has properties that enable it to be involved in different steps during the processing of recombination intermediates. On the one hand, it could be involved in the unwinding of an elongating invading strand from a donor strand, while on the other hand, it could be involved in the annealing of the elongated strand at a later step.
authors.affiliation: Botanical Institute II, Karlsruhe Institute of Technology (KIT), Kaiserstr. 12, 76128 Karlsruhe, Germany.
authors.forename: Sandra
authors.initials: S
authors.lastname: Blanck
authors.forename: Daniela
authors.initials: D
authors.lastname: Kobbe
authors.forename: Frank
authors.initials: F
authors.lastname: Hartung
authors.forename: Karin
authors.initials: K
authors.lastname: Fengler
authors.forename: Manfred
authors.initials: M
authors.lastname: Focke
authors.forename: Holger
authors.initials: H
authors.lastname: Puchta
mesh_terms: D000227:Adenine Nucleotides / Q000378:metabolism; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000378:metabolism*; D004265:DNA Helicases / Q000737:chemistry / Q000378:metabolism*; D045566:DNA, Cruciform / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000378:metabolism*; D008969:Molecular Sequence Data; D011995:Recombination, Genetic; D017386:Sequence Homology, Amino Acid
chemical_list: D000227:Adenine Nucleotides; D029681:Arabidopsis Proteins; D045566:DNA, Cruciform; D004277:DNA, Single-Stranded; D004265:DNA Helicases