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A structural determinant in the uracil DNA glycosylase superfamily for the removal of uracil from adenine/uracil base pairs
- Source :
- Nucleic Acids Research
- Publication Year :
- 2014
- Publisher :
- Oxford University Press (OUP), 2014.
-
Abstract
- The uracil DNA glycosylase superfamily consists of several distinct families. Family 2 mismatch-specific uracil DNA glycosylase (MUG) from Escherichia coli is known to exhibit glycosylase activity on three mismatched base pairs, T/U, G/U and C/U. Family 1 uracil N-glycosylase (UNG) from E. coli is an extremely efficient enzyme that can remove uracil from any uracil-containing base pairs including the A/U base pair. Here, we report the identification of an important structural determinant that underlies the functional difference between MUG and UNG. Substitution of a Lys residue at position 68 with Asn in MUG not only accelerates the removal of uracil from mismatched base pairs but also enables the enzyme to gain catalytic activity on A/U base pairs. Binding and kinetic analysis demonstrate that the MUG-K68N substitution results in enhanced ground state binding and transition state interactions. Molecular modeling reveals that MUG-K68N, UNG-N123 and family 5 Thermus thermophiles UDGb-A111N can form bidentate hydrogen bonds with the N3 and O4 moieties of the uracil base. Genetic analysis indicates the gain of function for A/U base pairs allows the MUG-K68N mutant to remove uracil incorporated into the genome during DNA replication. The implications of this study in the origin of life are discussed.
- Subjects :
- Models, Molecular
DNA Repair
Base Pair Mismatch
Base pair
Stereochemistry
Biology
03 medical and health sciences
chemistry.chemical_compound
Intrinsic termination
Escherichia coli
Genetics
Uracil
Uracil-DNA Glycosidase
Base Pairing
030304 developmental biology
0303 health sciences
Nucleic Acid Enzymes
Adenine
Escherichia coli Proteins
030302 biochemistry & molecular biology
DNA replication
Amino Acid Substitution
Biochemistry
chemistry
DNA glycosylase
Uracil-DNA glycosylase
DNA
Subjects
Details
- ISSN :
- 13624962 and 03051048
- Volume :
- 43
- Database :
- OpenAIRE
- Journal :
- Nucleic Acids Research
- Accession number :
- edsair.doi.dedup.....6b9adae2ee7fc85cfe3aa9d54f00657e