xni-deficient Escherichia coli are proficient for recombination and multiple pathways of repair.
Single-strand-dependent DNA exonucleases play important roles in DNA repair and recombination in all organisms. In Escherichia coli the redundant functions provided by the RecJ, ExoI, ExoVII and ExoX exonucleases are required for mismatch repair, UV resistance and homologous recombination. We have examined whether the xni gene product, the single-strand exonuclease ExoIX, is also a member of this group. We find that deletion of xni has no effect on the above processes, or on resistance to oxidative damage, even in combination with other exonuclease mutations. We conclude that the xni gene product does not belong to this group of nucleases that play redundant roles in DNA recombination and repair.
Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Rm S809A Mail Stop BCM225, Houston, TX 77030-3411, USA. mlombard@medicine.umaryland.edu
Mary-Jane
MJ
Lombardo
Ildiko
I
Aponyi
Mellanie P
MP
Ray
Margarita
M
Sandigursky
William A
WA
Franklin
Susan M
SM
Rosenberg
D020137:Base Pair Mismatch; D004260:DNA Repair; D004269:DNA, Bacterial / Q000378:metabolism / Q000528:radiation effects; D004277:DNA, Single-Stranded / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D005090:Exodeoxyribonucleases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D011995:Recombination, Genetic; D014466:Ultraviolet Rays
D004269:DNA, Bacterial; D004277:DNA, Single-Stranded; D029968:Escherichia coli Proteins; D005090:Exodeoxyribonucleases