Alternative mechanisms for coordinating polymerase alpha and MCM helicase.
Functional coordination between DNA replication helicases and DNA polymerases at replication forks, achieved through physical linkages, has been demonstrated in prokaryotes but not in eukaryotes. In Saccharomyces cerevisiae, we showed that mutations that compromise the activity of the MCM helicase enhance the physical stability of DNA polymerase alpha in the absence of their presumed linker, Mcm10. Mcm10 is an essential DNA replication protein implicated in the stable assembly of the replisome by virtue of its interaction with the MCM2-7 helicase and Polalpha. Dominant mcm2 suppressors of mcm10 mutants restore viability by restoring the stability of Polalpha without restoring the stability of Mcm10, in a Mec1-dependent manner. In this process, the single-stranded DNA accumulation observed in the mcm10 mutant is suppressed. The activities of key checkpoint regulators known to be important for replication fork stabilization contribute to the efficiency of suppression. These results suggest that Mcm10 plays two important roles as a linker of the MCM helicase and Polalpha at the elongating replication fork--first, to coordinate the activities of these two molecular motors, and second, to ensure their physical stability and the integrity of the replication fork.
Lee
Chanmi
C
Department of Molecular Biology & Genetics, Cornell University, Ithaca, New York 14853, USA.
Liachko
Ivan
I
Bouten
Roxane
R
Kelman
Zvi
Z
Tye
Bik K
BK
D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism*; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism*; D004256:DNA Polymerase I / Q000378:metabolism*; D004261:DNA Replication / Q000235:genetics / Q000502:physiology; D064110:Minichromosome Maintenance Proteins; D009154:Mutation / Q000235:genetics / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; C076365:MCM10 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D004256:DNA Polymerase I; C083536:POL1 protein, S cerevisiae; D004265:DNA Helicases; C069199:MCM2 protein, S cerevisiae; D064110:Minichromosome Maintenance Proteins