The Influence of a Palindromic Insertion on Plasmid Integration in Yeast

Ivan-Krešimir Svetec, Diana Stjepandić¹, Vladko Borić², Petar T. Mitrikeski and Zoran Zgaga*

¹ Present address: Functional Genome Analysis, Im Neuenheimer Feld 506, 69120 Heidelberg, Germany
² Present address: Laboratory of Biochemistry, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, HR-10 000 Zagreb, Croatia

Article history:
Received March 13, 2001
Accepted June 20, 2001

Key words:
palindrome, recombination, yeast, plasmid integration

Summary:
Palindromic sequences act as potential initiators of mitotic and meiotic recombination in yeast. We investigated the influence of a 102 base pair (bp) palindromic insertion present on a non-replicative plasmid on recombination with the yeast chromosome. First we show that the frequency of transformation was not significantly affected by the presence of the perfect palindrome in the CYC1 gene. However, as revealed by molecular analysis of transformants, both the proportion and the distribution of recombination events involving chromosomal homology were changed. Our results indicate that the palindrome present on the plasmid molecule was not efficiently processed in vivo to a double-strand break (DSB). We conclude that, in the absence of DNA replication, palindromic sequences are not potent initiators of recombination, but may influence subsequent step(s) and are preferentially lost during recombination process.

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