PDBsum entry 3f9v

Hydrolase

PDB id: 3f9v

Contents

Protein chain

595 a.a. *

* Residue conservation analysis

PDB id:

3f9v

Name:

Hydrolase

Title:

Crystal structure of a near full-length archaeal mcm: functional insights for an aaa+ hexameric helicase

Structure:

Minichromosome maintenance protein mcm. Chain: a. Engineered: yes

Source:

Sulfolobus solfataricus. Organism_taxid: 2287. Strain: p2. Gene: mcm, sso0774. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

4.35Å R-factor: 0.415 R-free: 0.481

Authors:

X.J.Chen,A.S.Brewster,G.G.Wang,X.Yu,W.Greenleaf,M.Tjajadi,M.Klein

Key ref:

A.S.Brewster et al. (2008). Crystal structure of a near-full-length archaeal MCM: functional insights for an AAA+ hexameric helicase. Proc Natl Acad Sci U S A, 105, 20191-20196. PubMed id: 19073923 DOI: 10.1073/pnas.0808037105

Date:

14-Nov-08 Release date: 30-Dec-08

Protein chain

Q9UXG1  (MCM_SULSO) -  Minichromosome maintenance protein MCM from Saccharolobus solfataricus (strain ATCC 35092 / DSM 1617 / JCM 11322 / P2)

Seq: 686 a.a.

Struc: 595 a.a.

Enzyme reactions

• Enzyme class: E.C.3.6.4.12 - Dna helicase.
• Reaction: ATP + H2O = ADP + phosphate + H⁺

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

DOI no: 10.1073/pnas.0808037105

Proc Natl Acad Sci U S A 105:20191-20196 (2008)

PubMed id: 19073923

Crystal structure of a near-full-length archaeal MCM: functional insights for an AAA+ hexameric helicase.

A.S.Brewster, G.Wang, X.Yu, W.B.Greenleaf, J.M.Carazo, M.Tjajadia, M.G.Klein, X.S.Chen.

ABSTRACT

The minichromosome maintenance protein (MCM) complex is an essential replicative helicase for DNA replication in Archaea and Eukaryotes. Whereas the eukaryotic complex consists of 6 homologous proteins (MCM2-7), the archaeon Sulfolobus solfataricus has only 1 MCM protein (ssoMCM), 6 subunits of which form a homohexamer. Here, we report a 4.35-A crystal structure of the near-full-length ssoMCM. The structure shows an elongated fold, with 5 subdomains that are organized into 2 large N- and C-terminal domains. A near-full-length ssoMCM hexamer generated based on the 6-fold symmetry of the N-terminal Methanothermobacter thermautotrophicus (mtMCM) hexamer shows intersubunit distances suitable for bonding contacts, including the interface around the ATP pocket. Four unusual beta-hairpins of each subunit are located inside the central channel or around the side channels in the hexamer. Additionally, the hexamer fits well into the double-hexamer EM map of mtMCM. Our mutational analysis of residues at the intersubunit interfaces and around the side channels demonstrates their critical roles for hexamerization and helicase function. These structural and biochemical results provide a basis for future study of the helicase mechanisms of the archaeal and eukaryotic MCM complexes in DNA replication.

Selected figure(s)

Figure 2.
Structural features of the ssoMCM hexamer. (A) Double hexameric EM map of mtMCM with the ssoMCM hexamer model fitting snugly inside the map (20). The PS1 hairpin is located near the side channels of the EM map (indicated by an arrow). (B) Side and top views of the ssoMCM hexamer model. Subunits are labeled a–f. Two subunits in the front are removed in the side view to reveal the interior. The 4 β-hairpins located inside the central and side channels are colored. (C) Close-up view of subunits a and b in the back side of the hexamer in B (side view). β-Hairpins are labeled as in Fig. 1B. The opening between the 2 neighboring subunits at the C terminus (side channel) is indicated. (D) Close-up top view as in B, showing the radial and helical nature of the 4 β-hairpins.

Figure 4.
Two possible DNA unwinding modes by MCM helicase. (A) Schematic representation of a MCM hexamer helicase. The 4 β-hairpins (NT, H2I, PS1, and EXT hairpins) are represented by short solid bars; the central channel and the side channels are in darker shades. (B) Steric exclusion model for a single-hexameric MCM helicase. (C) Side-channel extrusion model, showing ssDNA extruding from the side channel. DNA is shown as black lines. Arrows indicate direction of helicase movement.

Figures were selected by an automated process.