CLONING OF LARGE IMPERFECT PALINDROMES IN CIRCULAR AND LINEAR VECTORS

Data on comparative analysis of cloning of large imperfect artificial palindromes and one natural palindrome in the circular pUC19 and linea r pN15L vectors, constructed on the basis of temperate N15 bacteriopha ge minireplicon are presented. The artificial palindromes consisted of the two head-to-head oriented 5:5-kb lambda bacteriophage DNA fragmen ts interrupted by a short sequence of varied size. Natural palindrome was represented by the 12.5-kb BamHI fragment of Tetrahymena pyriformi s ribosomal genes cluster. Integration of some artificial palindromes and a natural palindrome into a circular vector resulted in a consider able decrease of its copy number. This was assumed to result from cruc iform formation mediated by supercoiling of a circular vector DNA, Thu s, a linear is vector preferable in cloning of inverted repeated DNA s equences.