RNA polymerase II and III transcription factors can stimulate DNA replication by modifying origin chromatin structures

Many transcription factors are multifunctional and also influence DNA repli cation. So far, their mechanism of action has remained elusive. Here we sho w that a DNA-binding protein could rely on the same biochemical activity th at activates transcription to stimulate replication from the yeast chromoso mal ARS1 origin. Unexpectedly, the ability to stimulate replication from th is origin was not restricted to polymerase II transcription factors, but wa s a property shared by polymerase III factors. Furthermore, activation of r eplication did not depend on the process of transcription, but rather on th e ability of DNA-binding transcription factors to remodel chromatin. The na tural ARS1 activator Abf1 and the other transcription factors that stimulat ed replication remodeled chromatin in a very similar manner. Moreover, the presence of a histone H3 mutant that was previously shown to generally incr ease transcription also facilitated replication from ARS1 and partially com pensated for the absence of a transcription factor. We propose that multifu nctional transcription factors work by influencing the chromatin architectu re at replication origins so as to generate a structure that is favorable t o the initiation of replication.