A nick-sensing DNA 3'-repair enzyme from Arabidopsis.
DNA single-strand breaks, a major cause of genome instability, often produce unconventional end groups that must be processed to restore terminal moieties suitable for reparative DNA gap filling or ligation. Here, we describe a bifunctional repair enzyme from Arabidopsis (named AtZDP) that recognizes DNA strand breaks and catalyzes the removal of 3'-end-blocking lesions. The isolated C-terminal domain of AtZDP is by itself competent for 3'-end processing, but not for strand break recognition. The N-terminal domain instead contains three Cys(3)-His zinc fingers and recognizes various kinds of damaged double-stranded DNA. Gapped DNA molecules are preferential targets of AtZDP, which bends them by approximately 73 degrees upon binding, as measured by atomic force microscopy. Potential partners of AtZDP were identified in the Arabidopsis genome using the human single-strand break repairosome as a reference. These data identify a novel pathway for single-strand break repair in which a DNA-binding 3'-phosphoesterase acts as a "nick sensor" for damage recognition, as the catalyst of one repair step, and possibly as a nucleation center for the assembly of a fully competent repair complex.
Petrucco
Stefania
S
Department of Biochemistry and Molecular Biology, University of Parma, Parma 43100, Italy. petrucco@unipr.it
Volpi
Giorgia
G
Bolchi
Angelo
A
Rivetti
Claudio
C
Ottonello
Simone
S
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics*; D004249:DNA Damage; D004260:DNA Repair; D018076:DNA, Complementary / Q000302:isolation & purification; D004277:DNA, Single-Stranded / Q000235:genetics; D008969:Molecular Sequence Data; D009708:Nucleotidases / Q000737:chemistry* / Q000235:genetics; D016335:Zinc Fingers
D018076:DNA, Complementary; D004277:DNA, Single-Stranded; D009708:Nucleotidases; C039170:deoxynucleotide 3'-phosphatase