Jia Yu
IR Iran
Research Article
DNA Spiral Supercoiling and Intramolecular Topological Interlink
Author(s): Xitai Huang, Jia Yu, Zhenfeng Zhang and Kou CaoXitai Huang, Jia Yu, Zhenfeng Zhang and Kou Cao
Escherichia coli chromosome DNA was observed previously to consist of subunits of Archimedean spirallike supercoiling. How do cells build such a DNA structure remains unknown. In the present study, atomic force microscopy (AFM) images showed that supercoiled pBR322 DNA forms a spiral structure upon intercalation with 0.5 μg/ml ethidium bromide (EB), which used to be considered as zero superhelical density. New evidence suggested that a novel topological bond, intramolecular topological interlink (ITL), promotes the DNA spiral formation. Without intercalation, the supercoiled pBR322 DNA displays plectonemical supercoil with uneven distribution of the supercoil density. Similar observation was also made when the DNA was over intercalated by EB (20 μg/ml). The results indicated .. View More»
DOI:
10.4172/1948-5948.S3-001