Dynamic localization of the DNA replication proteins MCM5 and MCM7 in plants.
Genome integrity in eukaryotes depends on licensing mechanisms that prevent loading of the minichromosome maintenance complex (MCM2-7) onto replicated DNA during S phase. Although the principle of licensing appears to be conserved across all eukaryotes, the mechanisms that control it vary, and it is not clear how licensing is regulated in plants. In this work, we demonstrate that subunits of the MCM2-7 complex are coordinately expressed during Arabidopsis (Arabidopsis thaliana) development and are abundant in proliferating and endocycling tissues, indicative of a role in DNA replication. We show that endogenous MCM5 and MCM7 proteins are localized in the nucleus during G1, S, and G2 phases of the cell cycle and are released into the cytoplasmic compartment during mitosis. We also show that MCM5 and MCM7 are topologically constrained on DNA and that the MCM complex is stable under high-salt conditions. Our results are consistent with a conserved replicative helicase function for the MCM complex in plants but not with the idea that plants resemble budding yeast by actively exporting the MCM complex from the nucleus to prevent unauthorized origin licensing and rereplication during S phase. Instead, our data show that, like other higher eukaryotes, the MCM complex in plants remains in the nucleus throughout most of the cell cycle and is only dispersed in mitotic cells.
Shultz
Randall W
RW
Department of Molecular and Structural Biochemistry , North Carolina State University, Raleigh, North Carolina 27695-7651, USA. rwshultz@ncsu.edu
Lee
Tae-Jin
TJ
Allen
George C
GC
Thompson
William F
WF
Hanley-Bowdoin
Linda
L
D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism; D004261:DNA Replication; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D064168:Minichromosome Maintenance Complex Component 7; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism; D051738:Origin Recognition Complex / Q000378:metabolism; D018517:Plant Roots / Q000166:cytology / Q000378:metabolism; D011485:Protein Binding; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport; D014026:Nicotiana / Q000166:cytology / Q000378:metabolism
D029681:Arabidopsis Proteins; D018797:Cell Cycle Proteins; D002843:Chromatin; C542431:MCM5 protein, Arabidopsis; D046912:Multiprotein Complexes; D051738:Origin Recognition Complex; D021122:Protein Subunits; D064168:Minichromosome Maintenance Complex Component 7; C093566:PROLIFERA protein, Arabidopsis