Smc5/6 functions with Sgs1-Top3-Rmi1 to complete chromosome replication at natural pause sites.

Smc5/6 is essential for genome structural integrity by yet unknown mechanisms. Here we find that Smc5/6 co-localizes with the DNA crossed-strand processing complex Sgs1-Top3-Rmi1 (STR) at genomic regions known as natural pausing sites (NPSs) where it facilitates Top3 retention. Individual depletions of STR subunits and Smc5/6 cause similar accumulation of ...
joint molecules (JMs) composed of reversed forks, double Holliday Junctions and hemicatenanes, indicative of Smc5/6 regulating Sgs1 and Top3 DNA processing activities. We isolate an intra-allelic suppressor of smc6-56 proficient in Top3 retention but affected in pathways that act complementarily with Sgs1 and Top3 to resolve JMs arising at replication termination. Upon replication stress, the smc6-56 suppressor requires STR and Mus81-Mms4 functions for recovery, but not Srs2 and Mph1 helicases that prevent maturation of recombination intermediates. Thus, Smc5/6 functions jointly with Top3 and STR to mediate replication completion and influences the function of other DNA crossed-strand processing enzymes at NPSs.
Mesh Terms:
Cell Cycle Proteins, DNA Repair, DNA Replication, DNA-Binding Proteins, Endonucleases, Flap Endonucleases, Genome, Fungal, RecQ Helicases, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins
Nat Commun
Date: Dec. 08, 2020
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