Model illustrating antisilencing activity of boundary element facilitated by minichromosome looping.

Top panels: Within the genome, the boundary element (BE) would block silencing when located between the silencer (E) and the URA3 gene but not upstream of the silencer. Bottom panels: In the minichromosomes, a close contact between the silencer (E) and the boundary element - BE (either STAR or TEF2-UASrpg) established by looping would prevent the silencing of the URA3 reporter by the silencer (E) irrespective of the position of the boundary element in relation to either the silencer or the URA3 reporter gene.