MCM forked substrate specificity involves dynamic interaction with the 5'-tail

J Biol Chem. 2007 Nov 23;282(47):34229-34. doi: 10.1074/jbc.M706300200. Epub 2007 Sep 20.


The archaeal minichromosome maintenance protein MCM forms a homohexameric complex that functions as the DNA replicative helicase and serves as a model system for its eukaryotic counterpart. Here, we applied single molecule fluorescence resonance energy transfer methods to probe the substrate specificity and binding mechanism of MCM from the hyperthermophilic Archaea Sulfolobus solfataricus on various DNA substrates. S. solfataricus MCM displays a binding preference for forked substrates relative to partial or full duplex substrates. Moreover, the nature of MCM binding to Y-shaped substrates is distinct in that MCM loads on the 3'-tail while interacting with the 5'-tail likely via the MCM surface. These results provide the first elucidation of a dynamic nature of interaction between a ring-shaped helicase interacting with an opposing single-stranded DNA tail. This interaction contributes to substrate selectivity and increases the stability of the forked DNA-MCM complex, with possible implications for the MCM unwinding mechanism.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Archaeal Proteins / chemistry*
  • Archaeal Proteins / metabolism
  • DNA, Archaeal / chemistry*
  • DNA, Archaeal / metabolism
  • DNA, Single-Stranded / chemistry*
  • DNA, Single-Stranded / metabolism
  • Fluorescence Resonance Energy Transfer
  • MADS Domain Proteins / chemistry*
  • MADS Domain Proteins / metabolism
  • Models, Biological
  • Protein Binding
  • Protein Structure, Quaternary
  • Substrate Specificity
  • Sulfolobus solfataricus / enzymology*


  • Archaeal Proteins
  • DNA, Archaeal
  • DNA, Single-Stranded
  • MADS Domain Proteins