Homologous pairing of DNA molecules by Ustilago rec1 protein is promoted by sequences of Z-DNA.
Plasmids containing Z-DNA stretches can be paired and linked by combined action of Ustilago rec1 protein and topoisomerase. The product formed is a hemicatenated dimer in which two DNA rings are topologically intertwined at a region of homology. Superhelicity governs the reaction. Formation of linked product is coupled with formation of Z-DNA in the plasmid, a process dependent on the superhelix density. Pairing appears to initiate within the Z-DNA sequence, not at the unwound B-Z junction. The reaction can be blocked by a Z-DNA-specific binding protein, namely Z-DNA antibody. Plasmids with alternating Z-DNA dG-dC sequences at different sites on otherwise homologous molecules can be linked at the dG-dC sequences. However, a plasmid with a (dG-dC)n.(dG-dC)n Z-DNA stretch cannot be linked with a plasmid containing a (dG-dT)n.(dC-dA)n Z-DNA stretch.
D000936:Antigen-Antibody Complex; D001483:Base Sequence; D004278:DNA, Superhelical / Q000235:genetics* / Q000276:immunology; D043211:Exodeoxyribonuclease V; D005656:Fungal Proteins / Q000502:physiology*; D006860:Hydrogen Bonding; D009690:Nucleic Acid Conformation; D010957:Plasmids; D011995:Recombination, Genetic; D012689:Sequence Homology, Nucleic Acid; D013329:Structure-Activity Relationship; D014588:Ustilago / Q000235:genetics
D000936:Antigen-Antibody Complex; D004278:DNA, Superhelical; D005656:Fungal Proteins; D043211:Exodeoxyribonuclease V