PDBsum entry 2zqe

DNA binding protein

PDB id: 2zqe

Contents

Protein chain

80 a.a. *

Waters ×104

* Residue conservation analysis

PDB id:

2zqe

Name:

DNA binding protein

Title:

Crystal structure of the smr domain of thermus thermophilus muts2

Structure:

Muts2 protein. Chain: a. Fragment: unp residue 663-744. Engineered: yes

Source:

Thermus thermophilus. Organism_taxid: 300852. Strain: hb8. Gene: ttha1645. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

1.70Å R-factor: 0.191 R-free: 0.227

Authors:

K.Fukui,Y.Kitamura,N.Nakagawa,R.Masui,S.Kuramitsu

Key ref:

K.Fukui et al. (2008). Crystal structure of MutS2 endonuclease domain and the mechanism of homologous recombination suppression. J Biol Chem, 283, 33417-33427. PubMed id: 18838375 DOI: 10.1074/jbc.M806755200

Date:

08-Aug-08 Release date: 30-Sep-08

Protein chain

Q5SHT5  (MUTS2_THET8) -  Endonuclease MutS2 from Thermus thermophilus (strain ATCC 27634 / DSM 579 / HB8)

Seq: 744 a.a.

Struc: 80 a.a.

Enzyme reactions

• Enzyme class 2: E.C.3.1.12.- - ?????
• Enzyme class 3: E.C.3.6.4.- - ?????

Note, where more than one E.C. class is given (as above), each may correspond to a different protein domain or, in the case of polyprotein precursors, to a different mature protein.

DOI no: 10.1074/jbc.M806755200

J Biol Chem 283:33417-33427 (2008)

PubMed id: 18838375

Crystal structure of MutS2 endonuclease domain and the mechanism of homologous recombination suppression.

K.Fukui, N.Nakagawa, Y.Kitamura, Y.Nishida, R.Masui, S.Kuramitsu.

ABSTRACT

DNA recombination events need to be strictly regulated, because an increase in the recombinational frequency causes unfavorable alteration of genetic information. Recent studies revealed the existence of a novel anti-recombination enzyme, MutS2. However, the mechanism by which MutS2 inhibits homologous recombination has been unknown. Previously, we found that Thermus thermophilus MutS2 (ttMutS2) harbors an endonuclease activity and that this activity is confined to the C-terminal domain, whose amino acid sequence is widely conserved in a variety of proteins with unknown function from almost all organisms ranging from bacteria to man. In this study, we determined the crystal structure of the ttMutS2 endonuclease domain at 1.7-angstroms resolution, which resembles the structure of the DNase I-like catalytic domain of Escherichia coli RNase E, a sequence-nonspecific endonuclease. The N-terminal domain of ttMutS2, however, recognized branched DNA structures, including the Holliday junction and D-loop structure, a primary intermediate in homologous recombination. The full-length of ttMutS2 digested the branched DNA structures at the junction. These results indicate that ttMutS2 suppresses homologous recombination through a novel mechanism involving resolution of early intermediates.

Selected figure(s)

Figure 1.
A schematic representation of the primary structures of ttMutS1 and ttMutS2. Regions represented as mismatch-recognition, dsDNA-binding, and ATP-binding and dimerization domains in ttMutS1 are the counterparts of T. aquaticus MutS whose crystal structure has been solved (55). The dsDNA-binding and ATP-binding domains of ttMutS2 show >30% identity in the respective domains of ttMutS.

Figure 7.
The proposed model for the mechanism of homologous recombination suppression by MutS2. MutS2 recognizes an early intermediate, such as the D-loop structure, and incises it. The incision of the D-loop structure prevents the formation of the Holliday junction. Helicases and/or exonucleases remove the remaining DNA fragments.

The above figures are reprinted from an Open Access publication published by the ASBMB: J Biol Chem (2008, 283, 33417-33427) copyright 2008.

Figures were selected by the author.