Homologous recombination enhancement conferred by the Z-DNA motif d(TG)30 is abrogated by simian virus 40 T antigen binding to adjacent DNA sequences.
The Z-DNA motif polydeoxythymidylic-guanylic [d(TG)].polydeoxyadenylic-cytidylic acid [d(AC)], present throughout eucaryotic genomes, is capable of readily forming left-handed Z-DNA in vitro and has been shown to promote homologous recombination. The effects of simian virus 40 T-antigen-dependent substrate replication upon the stimulation of recombination conferred by the Z-DNA motif d(TG)30 were analyzed. Presence of d(TG)30 adjacent to a T-antigen-binding site I can stimulate homologous recombination between nonreplicating plasmids, providing that T antigen is absent, in both simian CV-1 cells and human EJ cells (W. P. Wahls, L. J. Wallace, and P. D. Moore, Mol. Cell. Biol. 10:785-793). It has also been shown elsewhere that the presence of d(TG)n not adjacent to the T-antigen-binding site can stimulate homologous recombination in simian virus 40 molecules replicating in the presence of T antigen (P. Bullock, J. Miller, and M. Botchan, Mol. Cell. Biol. 6:3948-3953, 1986). However, it is demonstrated here that d(TG)30 nine base pairs distant from a T-antigen-binding site bound with T antigen does not stimulate recombination between either replicating or nonreplicating substrates in somatic cells. The bound T antigen either prevents the d(TG)30 sequence from acquiring a recombinogenic configuration (such as left-handed Z-DNA), or it prevents the interaction of recombinase proteins with the sequence by stearic hindrance.
Wahls
W P
WP
Department of Microbiology and Immunology, University of Illinois, College of Medicine, Chicago 60612.
Moore
P D
PD
D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000235:genetics*; D001483:Base Sequence; D002460:Cell Line; D002872:Chromosome Deletion; D004247:DNA / Q000235:genetics*; D004261:DNA Replication; D005814:Genes, Viral; D005822:Genetic Vectors; D006801:Humans; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011089:Polydeoxyribonucleotides / Q000235:genetics*; D011995:Recombination, Genetic; D013539:Simian virus 40 / Q000235:genetics* / Q000276:immunology; D014162:Transfection; D015678:Viral Structural Proteins / Q000235:genetics
D000952:Antigens, Polyomavirus Transforming; D011089:Polydeoxyribonucleotides; D015678:Viral Structural Proteins; C017650:polydeoxy(guanine-thymine) nucleotide; C028333:poly(d(A-C).d(G-T)); D004247:DNA