Synthesis of a DNA knot containing both positive and negative nodes

Abstract

A figure-eight (4 1 ) knot, staining two positive and two negative nodes, has been synthesized by ligating a single-stranded DNA molecule into a closed cycle. The molecule consists of two single-turn double-helical domains connected by four dT 14 or dT 15 linkers. One of the domains contains the sequence (dCpdGp) 6 , which is capable of forming left-handed Z-DNA. Ligation yields a trefoil (3 1 ) knot or a 4 1 knot, depending upon the conditions in solution