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Thermoplasma acidophilum Cdc6 protein stimulates MCM helicase activity by regulating its ATPase activity

Gyri Teien Haugland1, Nozomi Sakakibara, Angel L Pey

  • 1Department of Biology, University of Bergen, N-5020 Bergen, Norway.

Nucleic Acids Research
|September 2, 2008
PubMed

Insights

The Cdc6 protein from Thermoplasma acidophilum stimulates minichromosome maintenance (MCM) helicase activity by boosting its ATPase function. An intact Cdc6 is necessary, but ATP binding/hydrolysis by Cdc6 is not required for this stimulation.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Structural Biology

Background:

  • Minichromosome maintenance (MCM) proteins are the replicative helicases in archaea.
  • Typically, Cdc6 interaction inhibits MCM helicase activity, except in Thermoplasma acidophilum.

Purpose of the Study:

  • To elucidate the mechanism by which Cdc6 protein stimulates MCM helicase activity in Thermoplasma acidophilum.
  • To determine the role of Cdc6 protein structure and ATPase activity in MCM helicase stimulation.

Main Methods:

  • Site-specific protein substitutions.
  • Truncated and chimeric protein analysis.
  • ATPase activity assays.

Main Results:

  • Cdc6 protein stimulates MCM helicase activity by enhancing MCM's ATPase activity.
  • An intact Cdc6 protein is essential for this stimulatory effect.
  • ATP binding and hydrolysis by Cdc6 are not required for stimulation.

Conclusions:

  • Cdc6 binding induces a conformational change in MCM, enhancing ATP hydrolysis and helicase function.
  • This interaction represents a unique mechanism for regulating helicase activity in archaea.

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