PT - JOURNAL ARTICLE AU - Lance D. Langston AU - Ryan Mayle AU - Grant D. Schauer AU - Olga Yurieva AU - Daniel Zhang AU - Nina Y. Yao AU - Roxana Georgescu AU - Michael E. O’Donnell TI - Mcm10 functions to isomerize CMG-DNA for replisome bypass of DNA blocks AID - 10.1101/146837 DP - 2017 Jan 01 TA - bioRxiv PG - 146837 4099 - http://biorxiv.org/content/early/2017/06/06/146837.short 4100 - http://biorxiv.org/content/early/2017/06/06/146837.full AB - Replicative helicases of all cell types are rings that unwind DNA by steric exclusion in which the helicase ring only encircles the tracking strand, excluding the other strand outside the ring. Steric exclusion mediated unwinding enables helicase rings to bypass blocks on the strand that is excluded from the central channel. Unlike other replicative helicases, eukaryotic CMG encircles duplex DNA at a forked junction and is stopped by a block on the non-tracking (lagging) strand. This report demonstrates that Mcm10, an essential replication protein unique to eukaryotes, binds CMG and enables the replisome to bypass blocks on the non-tracking strand, implying that Mcm10 isomerizes the CMG-DNA complex to position only one strand through the central channel. A similar CMG-DNA isomerization is needed at the origin for head-to-head CMGs to bypass one another during formation of bidirectional replication forks.