Changes in the conformation of the Vsr endonuclease amino-terminal domain accompany DNA cleavage.
In Escherichia coli, T/G mismatches arising from deamination of 5-methylcytosine to thymine are converted to CG base pairs by the very short patch (VSP) repair pathway. DNA Polymerase I removes and resynthesizes the mismatched T starting from a 5'-nick created by the Vsr endonuclease. We used limited trypsinolysis to probe conformational changes in the N-terminal domain of Vsr in response to DNA binding, DNA cleavage and interaction with the polymerase. Our data show that the domain becomes trypsin resistant only under conditions that allow DNA cleavage, while interaction with the polymerase restores trypsin sensitivity. We suggest that the domain changes its conformation as a result of DNA nicking, and that DNA Pol I releases Vsr from the nick by reversing that conformational change.
Polosina
Yaroslava Y
YY
Department of Biochemistry and Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, BC, V8W 3P6, Canada. polosina@uvic.ca
Cupples
Claire G
CG
D053837:DNA Cleavage; D004256:DNA Polymerase I / Q000737:chemistry / Q000378:metabolism; D004706:Endodeoxyribonucleases / Q000737:chemistry* / Q000378:metabolism*; D011487:Protein Conformation; D017434:Protein Structure, Tertiary
D004256:DNA Polymerase I; D004706:Endodeoxyribonucleases; C071421:vsr endonuclease