Plant Molecular Biology

, Volume 77, Issue 6, pp 537-545

First online:

Plant MCM proteins: role in DNA replication and beyond

  • Narendra TutejaAffiliated withInternational Centre for Genetic Engineering and Biotechnology (ICGEB) Email author 
  • , Ngoc Quang TranAffiliated withDepartment of Biological Chemistry and Molecular Pharmacology, Harvard Medical School
  • , Hung Quang DangAffiliated withInternational Centre for Genetic Engineering and Biotechnology (ICGEB)
  • , Renu TutejaAffiliated withInternational Centre for Genetic Engineering and Biotechnology (ICGEB)

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Mini-chromosome maintenance (MCM) proteins form heterohexameric complex (MCM2–7) to serve as licensing factor for DNA replication to make sure that genomic DNA is replicated completely and accurately once during S phase in a single cell cycle. MCMs were initially identified in yeast for their role in plasmid replication or cell cycle progression. Each of six MCM contains highly conserved sequence called “MCM box”, which contains two ATPase consensus Walker A and Walker B motifs. Studies on MCM proteins showed that (a) the replication origins are licensed by stable binding of MCM2–7 to form pre-RC (pre-replicative complex) during G1 phase of the cell cycle, (b) the activation of MCM proteins by CDKs (cyclin-dependent kinases) and DDKs (Dbf4-dependent kinases) and their helicase activity are important for pre-RC to initiate the DNA replication, and (c) the release of MCMs from chromatin renders the origins “unlicensed”. DNA replication licensing in plant is, in general, less characterized. The MCMs have been reported from Arabidopsis, maize, tobacco, pea and rice, where they are found to be highly expressed in dividing tissues such as shoot apex and root tips, localized in nucleus and cytosol and play important role in DNA replication, megagametophyte and embryo development. The identification of six MCM coding genes from pea and Arabidopsis suggest six distinct classes of MCM protein in higher plant, and the conserved function right across the eukaryotes. This overview of MCMs contains an emphasis on MCMs from plants and the novel role of MCM6 in abiotic stress tolerance.


Cell cycle Pre-replicative complex (pre-RC) DNA replication licensing Licensing factor Mini-chromosome maintenance (MCM)