A single subunit MCM6 from pea forms homohexamer and functions as DNA helicase

Area of Science:

• Molecular Biology
• Plant Science
• Biochemistry

Background:

• DNA replication initiation is regulated by a complex of approximately twenty protein factors.
• The minichromosome maintenance (MCM2-7) complex is a conserved, essential replicative helicase involved in DNA replication.

Purpose of the Study:

• To isolate and characterize the MCM6 subunit from pea plants.
• To investigate the enzymatic activities and self-interaction properties of pea MCM6.

Main Methods:

• Isolation and purification of recombinant pea MCM6 protein.
• Assays for DNA helicase, ATP-binding, and ATPase activities.
• In vitro self-interaction studies and Western blot analysis.
• In vivo localization studies using immunostaining and confocal microscopy.

Main Results:

• Purified recombinant pea MCM6 possesses ATP-dependent 3'-5' DNA helicase, ATP-binding, and ATPase activities.
• The complete MCM6 protein self-interacts in vitro to form an active homohexamer.
• Anti-MCM6 antibodies inhibit all enzymatic activities of the protein.
• MCM6 localizes to both the nucleus and cytosol in vivo.

Conclusions:

• Pea MCM6, as a single subunit, possesses DNA helicase activity, a unique finding for plant MCM proteins.
• This activity was previously only reported for heteromultimers of MCM proteins in animal systems.
• The findings contribute to a deeper understanding of DNA replication mechanisms in plants.