Structure of RecJ Exonuclease Defines Its Specificity for Single-stranded DNA

RecJ is a single-stranded DNA (ssDNA)-specific 5′-3′ exonuclease that plays an important role in DNA repair and recombination. To elucidate how RecJ achieves its high specificity for ssDNA, we determined the entire structures of RecJ both in a ligand-free form and in a complex with Mn2+ or Mg2+ by x...

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Bibliographic Details
Published in:The Journal of biological chemistry 2010-03, Vol.285 (13), p.9762-9769
Main Authors: Wakamatsu, Taisuke, Kitamura, Yoshiaki, Kotera, Yutaro, Nakagawa, Noriko, Kuramitsu, Seiki, Masui, Ryoji
Format: Article
Language:English
Subjects:
Bacterial Proteins - chemistry
Bacterial Proteins - genetics
Crystallography, X-Ray - methods
DNA And Chromosomes
DNA Recombination
DNA Repair
DNA, Single-Stranded - chemistry
DNA, Single-Stranded - genetics
DNase
Enzyme Mechanisms
Enzyme Structure
Exodeoxyribonucleases - chemistry
Exodeoxyribonucleases - genetics
Hydrolysis
Ions
Kinetics
Magnesium - chemistry
Manganese - chemistry
Models, Molecular
OB fold
Oligonucleotides - chemistry
Oligosaccharides - chemistry
Protein Conformation
Protein Domains
Protein Folding
Protein Metal Ion Interaction
Protein Structure and Folding
Protein Structure, Tertiary
Protein-DNA Interaction
RecJ
Thermus thermophilus - enzymology
Thermus thermophilus - genetics
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Summary:RecJ is a single-stranded DNA (ssDNA)-specific 5′-3′ exonuclease that plays an important role in DNA repair and recombination. To elucidate how RecJ achieves its high specificity for ssDNA, we determined the entire structures of RecJ both in a ligand-free form and in a complex with Mn2+ or Mg2+ by x-ray crystallography. The entire RecJ consists of four domains that form a molecule with an O-like structure. One of two newly identified domains had structural similarities to an oligonucleotide/oligosaccharide-binding (OB) fold. The OB fold domain alone could bind to DNA, indicating that this domain is a novel member of the OB fold superfamily. The truncated RecJ containing only the core domain exhibited much lower affinity for the ssDNA substrate compared with intact RecJ. These results support the hypothesis that these structural features allow specific binding of RecJ to ssDNA. In addition, the structure of the RecJ-Mn2+ complex suggests that the hydrolysis reaction catalyzed by RecJ proceeds through a two-metal ion mechanism.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M109.096487