The yeast Pif1 family helicase RRM3 promotes DNA unwinding during replisome swivelling
Seminar Room 1, Newton Institute
During termination of DNA replication, replisomes overcome the topological tension that occurs as forks converge by coupling final unwinding with fork swivelling. Here I show that cells lacking the DNA helicase RRM3 accumulate terminating late replication intermediates (LRI) in plasmids both with and without characterised pause sites. Rrm3 deletion does not alter the level of swivelling that occurs during termination but its depletion extends the lifetime of LRI while itís over-expression leads to the rapid unwinding of the LRI. Therefore RRM3 promotes DNA unwinding when the replisome swivels during termination. Potentially, this activity is also generally utilised during DNA replication to bypass topological blocks.