Poster: Epigenetics & gene silencing

Abs # 833: Discovery of a Genetic Insulator in Arabidopsis thaliana

Presenter:	Gan, Susheng , sg288@cornell.edu
Authors	Yang, Xiaohan  (A)   Xu, Hengping  (B)   Xie, Mingtang  (B)   Gan, Susheng  (A) (B)
Affiliations:	(A): Cornell University (B): University of Kentucky
Web Site:	http://www.hort.cornell.edu/gan

A 16-bp palindromic DNA sequence of Arabidopsis, 5'-GAATATATATATATTC-3', is shown to function as a genetic insulator that can block enhancers and eliminate position effects but possesses no negative effect on a promoter when placed outside of it. The palindromic nature per se is not sufficient for the insulating effect because its transversion mutant M3 (5’-GAATATcgcgATATTC-3’) and the lacO (5'-ATTGTGAGCGCTCACAAT-3'), which both are perfect palindromes, fail to insulate gene expression. The Arabidopsis insulator buffers transgene expression at the transcriptional level as revealed by nuclear run-on assays, and its insulating function requires nuclear protein(s) that specifically bind to it. This represents not only the first report of a genetic insulator of plant origin, but it is also by far the shortest insulator so far discovered.