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Structural analysis of the Sulfolobus solfataricus MCM protein N-terminal domain

Wei Liu1, Biagio Pucci, Mosè Rossi

  • 1Center of Structural Biochemistry, Karolinska Institutet NOVUM, 141 57 Huddinge, Sweden. wei.liu@ki.se

Nucleic Acids Research
|April 18, 2008
PubMed

Insights

The crystal structure of Sulfolobus solfataricus MCM (Sso MCM) reveals a unique ring-like assembly. This DNA helicase structure suggests a mechanism for binding single-stranded DNA, crucial for replication.

Area of Science:

  • Structural Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Mini-Chromosome Maintenance (MCM) proteins are essential candidates for replicative DNA helicases in eukaryotes and archaea.
  • Understanding the structural basis of MCM protein function is critical for elucidating DNA replication mechanisms.

Purpose of the Study:

  • To determine the crystal structure of the N-terminal domain of the Sulfolobus solfataricus MCM (Sso MCM) protein.
  • To investigate the structural basis for Sso MCM's interaction with DNA and propose a functional mechanism.

Main Methods:

  • X-ray crystallography was used to obtain the 2.8 Å crystal structure of the Sso MCM N-terminal domain (residues 1-268).
  • DNA-binding assays were performed to assess the binding preference of Sso MCM for single-stranded versus double-stranded DNA.

Main Results:

  • The crystal structure revealed a single-hexameric, ring-like architecture for Sso MCM, distinct from other known MCM structures.
  • Sso MCM possesses a narrower central channel compared to its counterpart in Methanothermobacter thermoautotrophicus (Mth), favoring single-stranded DNA binding.
  • The zinc-binding domain plays a crucial role in nucleic acid interaction, suggesting a molecular clamp-like function for grasping single-stranded DNA.

Conclusions:

  • The Sso MCM N-terminal domain's structure supports a model where it acts as a molecular clamp, specifically binding single-stranded DNA.
  • These findings provide insights into potential DNA unwinding mechanisms mediated by MCM proteins.
  • The unique structural features of Sso MCM highlight the diversity of DNA helicase mechanisms across different archaeal species.

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