BIOLOGICAL CHARACTERISTICS OF PALINDROMIC DNA(II)

Abstract

We have prepared plasmids containing various lengths of palindrome. When the palindrome is longer than 184bp, the plasmid can not grow in wild-type Escherichia coli, but a plasmid with a palindrome less than 95bp can. The absolute length of the palindrome determines whether the plasmid can grow or not. Electron microscopy confirmed that the plasmid with palindrome had a relaxed form with cruciform structure. The length of the protruding region is not the same size as the palindrome inserted into the plasmid but the self-annealing length seems to be just enough to make the twisted molecule into the relaxed form. Although plasmids with palindromes longer than 184bp multiply in E. coli recB recC sbcB recF, deletions occur in the palindromes and these deletions seem to occur at a specific site.