FIG. 6.

Multiple copies of the A and B1 elements can functionally substitute for the HML ARS cluster in generating a replication fork pause, as determined by 2D gel electrophoresis of replication intermediates from the indicated strains probed for the specific restriction fragment diagrammed in the maps. The HML ARS cluster was substituted by a mutated ARS305 derivative (mt305) which contains the A and B1 elements and mutated sequences in place of the B4 element and the easily unwound sequences. (A) One copy of mt305 replacing the natural HML ARS cluster was analyzed on a 3.2-kb EcoRI/FspI genomic fragment. (B) Five copies of mt305 replacing the HML ARS cluster were analyzed on a 4.4-kb EcoRI/FspI genomic fragment. The arrowhead denotes a pause signal.