Browse
Submit Data
Databases
API
Help

Dataset Information

30 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

New family of deamination repair enzymes in uracil-DNA glycosylase superfamily.

ABSTRACT: DNA glycosylases play a major role in the repair of deaminated DNA damage. Previous investigations identified five families within the uracil-DNA glycosylase (UDG) superfamily. All enzymes within the superfamily studied thus far exhibit uracil-DNA glycosylase activity. Here we identify a new class of DNA glycosylases in the UDG superfamily that lacks UDG activity. Instead, these enzymes act as hypoxanthine-DNA glycosylases in vitro and in vivo. Molecular modeling and structure-guided mutational analysis allowed us to identify a unique catalytic center in this class of DNA glycosylases. Based on unprecedented biochemical properties and phylogenetic analysis, we propose this new class of DNA repair glycosylases that exists in bacteria, archaea, and eukaryotes as family 6 and designate it as the hypoxanthine-DNA glycosylase family. This study demonstrates the structural evolvability that underlies substrate specificity and catalytic flexibility in the evolution of enzymatic function.

SUBMITTER: Lee HW

PROVIDER: S-EPMC3173141 | biostudies-literature | 2011 Sep

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

New family of deamination repair enzymes in uracil-DNA glycosylase superfamily.

Lee Hyun-Wook HW Dominy Brian N BN Cao Weiguo W

The Journal of biological chemistry 20110603 36

DNA glycosylases play a major role in the repair of deaminated DNA damage. Previous investigations identified five families within the uracil-DNA glycosylase (UDG) superfamily. All enzymes within the superfamily studied thus far exhibit uracil-DNA glycosylase activity. Here we identify a new class of DNA glycosylases in the UDG superfamily that lacks UDG activity. Instead, these enzymes act as hypoxanthine-DNA glycosylases in vitro and in vivo. Molecular modeling and structure-guided mutational ...[more]

PMID: 21642431

Similar Datasets

A novel uracil-DNA glycosylase family related to the helix-hairpin-helix DNA glycosylase superfamily.

Project description:Cytosine bases can be deaminated spontaneously to uracil, causing DNA damage. Uracil-DNA glycosylase (UDG), a ubiquitous uracil-excising enzyme found in bacteria and eukaryotes, is one of the enzymes that repair this kind of DNA damage. To date, no UDG-coding gene has been identified in Methanococcus jannaschii, although its entire genome was deciphered. Here, we have identified and characterized a novel UDG from M.jannaschii designated as MjUDG. It efficiently removed uracil from both single- and double-stranded DNA. MjUDG also catalyzes the excision of 8-oxoguanine from DNA. MjUDG has a helix-hairpin-helix motif and a [4Fe-4S]-binding cluster that is considered to be important for the DNA binding and catalytic activity. Although MjUDG shares these features with other structural families such as endonuclease III and mismatch-specific DNA glycosylase (MIG), unique conserved amino acids and substrate specificity distinguish MjUDG from other families. Also, a homologous member of MjUDG was identified in Aquifex aeolicus. We report that MjUDG belongs to a novel UDG family that has not been described to date.

| S-EPMC153747 | biostudies-literature

A unique uracil-DNA binding protein of the uracil DNA glycosylase superfamily.

Project description:Uracil DNA glycosylases (UDGs) are an important group of DNA repair enzymes, which pioneer the base excision repair pathway by recognizing and excising uracil from DNA. Based on two short conserved sequences (motifs A and B), UDGs have been classified into six families. Here we report a novel UDG, UdgX, from Mycobacterium smegmatis and other organisms. UdgX specifically recognizes uracil in DNA, forms a tight complex stable to sodium dodecyl sulphate, 2-mercaptoethanol, urea and heat treatment, and shows no detectable uracil excision. UdgX shares highest homology to family 4 UDGs possessing Fe-S cluster. UdgX possesses a conserved sequence, KRRIH, which forms a flexible loop playing an important role in its activity. Mutations of H in the KRRIH sequence to S, G, A or Q lead to gain of uracil excision activity in MsmUdgX, establishing it as a novel member of the UDG superfamily. Our observations suggest that UdgX marks the uracil-DNA for its repair by a RecA dependent process. Finally, we observed that the tight binding activity of UdgX is useful in detecting uracils in the genomes.

| S-EPMC4787834 | biostudies-literature

Phylogenomic analysis of the uracil-DNA glycosylase superfamily.

Project description:The spontaneous deamination of cytosine produces uracil mispaired with guanine in DNA, which will produce a mutation, unless repaired. In all domains of life, uracil-DNA glycosylases (UDGs) are responsible for the elimination of uracil from DNA. Thus, UDGs contribute to the integrity of the genetic information and their loss results in mutator phenotypes. We are interested in understanding the role of UDG genes in the evolutionary variation of the rate and the spectrum of spontaneous mutations. To this end, we determined the presence or absence of the five main UDG families in more than 1,000 completely sequenced genomes and analyzed their patterns of gene loss and gain in eubacterial lineages. We observe nonindependent patterns of gene loss and gain between UDG families in Eubacteria, suggesting extensive functional overlap in an evolutionary timescale. Given that UDGs prevent transitions at G:C sites, we expected the loss of UDG genes to bias the mutational spectrum toward a lower equilibrium G + C content. To test this hypothesis, we used phylogenetically independent contrasts to compare the G + C content at intergenic and 4-fold redundant sites between lineages where UDG genes have been lost and their sister clades. None of the main UDG families present in Eubacteria was associated with a higher G + C content at intergenic or 4-fold redundant sites. We discuss the reasons of this negative result and report several features of the evolution of the UDG superfamily with implications for their functional study. uracil-DNA glycosylase, mutation rate evolution, mutational bias, GC content, DNA repair, mutator gene.

| S-EPMC3107667 | biostudies-literature

Poxvirus uracil-DNA glycosylase-An unusual member of the family I uracil-DNA glycosylases.

Project description:Uracil-DNA glycosylases are ubiquitous enzymes, which play a key role repairing damages in DNA and in maintaining genomic integrity by catalyzing the first step in the base excision repair pathway. Within the superfamily of uracil-DNA glycosylases family I enzymes or UNGs are specific for recognizing and removing uracil from DNA. These enzymes feature conserved structural folds, active site residues and use common motifs for DNA binding, uracil recognition and catalysis. Within this family the enzymes of poxviruses are unique and most remarkable in terms of amino acid sequences, characteristic motifs and more importantly for their novel non-enzymatic function in DNA replication. UNG of vaccinia virus, also known as D4, is the most extensively characterized UNG of the poxvirus family. D4 forms an unusual heterodimeric processivity factor by attaching to a poxvirus-specific protein A20, which also binds to the DNA polymerase E9 and recruits other proteins necessary for replication. D4 is thus integrated in the DNA polymerase complex, and its DNA-binding and DNA scanning abilities couple DNA processivity and DNA base excision repair at the replication fork. The adaptations necessary for taking on the new function are reflected in the amino acid sequence and the three-dimensional structure of D4. An overview of the current state of the knowledge on the structure-function relationship of D4 is provided here.

| S-EPMC5119566 | biostudies-literature

Project description:Enzymes in Uracil DNA glycosylase (UDG) superfamily are essential for the removal of uracil. Family 4 UDGa is a robust uracil DNA glycosylase that only acts on double-stranded and single-stranded uracil-containing DNA. Based on mutational, kinetic and modeling analyses, a catalytic mechanism involving leaving group stabilization by H155 in motif 2 and water coordination by N89 in motif 3 is proposed. Mutual Information analysis identifies a complexed correlated mutation network including a strong correlation in the EG doublet in motif 1 of family 4 UDGa and in the QD doublet in motif 1 of family 1 UNG. Conversion of EG doublet in family 4 Thermus thermophilus UDGa to QD doublet increases the catalytic efficiency by over one hundred-fold and seventeen-fold over the E41Q and G42D single mutation, respectively, rectifying the strong correlation in the doublet. Molecular dynamics simulations suggest that the correlated mutations in the doublet in motif 1 position the catalytic H155 in motif 2 to stabilize the leaving uracilate anion. The integrated approach has important implications in studying enzyme evolution and protein structure and function.

| S-EPMC5387724 | biostudies-literature

A structural determinant in the uracil DNA glycosylase superfamily for the removal of uracil from adenine/uracil base pairs.

Project description: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.

| S-EPMC4333384 | biostudies-literature

Uracil-DNA glycosylases-structural and functional perspectives on an essential family of DNA repair enzymes.

Project description:Uracil-DNA glycosylases (UDGs) are evolutionarily conserved DNA repair enzymes that initiate the base excision repair pathway and remove uracil from DNA. The UDG superfamily is classified into six families based on their substrate specificity. This review focuses on the family I enzymes since these are the most extensively studied members of the superfamily. The structural basis for substrate specificity and base recognition as well as for DNA binding, nucleotide flipping and catalytic mechanism is discussed in detail. Other topics include the mechanism of lesion search and molecular mimicry through interaction with uracil-DNA glycosylase inhibitors. The latest studies and findings detailing structure and function in the UDG superfamily are presented.

| S-EPMC4253808 | biostudies-literature

Escherichia coli DNA repair helicase Lhr is also a uracil-DNA glycosylase.

Project description:DNA glycosylases protect genetic fidelity during DNA replication by removing potentially mutagenic chemically damaged DNA bases. Bacterial Lhr proteins are well-characterized DNA repair helicases that are fused to additional 600-700 amino acids of unknown function, but with structural homology to SecB chaperones and AlkZ DNA glycosylases. Here, we identify that Escherichia coli Lhr is a uracil-DNA glycosylase (UDG) that depends on an active site aspartic acid residue. We show that the Lhr DNA helicase activity is functionally independent of the UDG activity, but that the helicase domains are required for fully active UDG activity. Consistent with UDG activity, deletion of lhr from the E. coli chromosome sensitized cells to oxidative stress that triggers cytosine deamination to uracil. The ability of Lhr to translocate single-stranded DNA and remove uracil bases suggests a surveillance role to seek and remove potentially mutagenic base changes during replication stress.

| S-EPMC10953399 | biostudies-literature

Specificity and catalytic mechanism in family 5 uracil DNA glycosylase.

Project description:UDGb belongs to family 5 of the uracil DNA glycosylase (UDG) superfamily. Here, we report that family 5 UDGb from Thermus thermophilus HB8 is not only a uracil DNA glycosyase acting on G/U, T/U, C/U, and A/U base pairs, but also a hypoxanthine DNA glycosylase acting on G/I, T/I, and A/I base pairs and a xanthine DNA glycosylase acting on all double-stranded and single-stranded xanthine-containing DNA. Analysis of potentials of mean force indicates that the tendency of hypoxanthine base flipping follows the order of G/I > T/I, A/I > C/I, matching the trend of hypoxanthine DNA glycosylase activity observed in vitro. Genetic analysis indicates that family 5 UDGb can also act as an enzyme to remove uracil incorporated into DNA through the existence of dUTP in the nucleotide pool. Mutational analysis coupled with molecular modeling and molecular dynamics analysis reveals that although hydrogen bonding to O2 of uracil underlies the UDG activity in a dissociative fashion, Tth UDGb relies on multiple catalytic residues to facilitate its excision of hypoxanthine and xanthine. This study underscores the structural and functional diversity in the UDG superfamily.

| S-EPMC4140252 | biostudies-literature

An unconventional family 1 uracil DNA glycosylase in Nitratifractor salsuginis.

Project description:The uracil DNA glycosylase superfamily consists of at least six families with a diverse specificity toward DNA base damage. Family 1 uracil N-glycosylase (UNG) exhibits exclusive specificity on uracil-containing DNA. Here, we report a family 1 UNG homolog from Nitratifractor salsuginis with distinct biochemical features that differentiate it from conventional family 1 UNGs. Globally, the crystal structure of N. salsuginisUNG shows a few additional secondary structural elements. Biochemical and enzyme kinetic analysis, coupled with structural determination, molecular modeling, and molecular dynamics simulations, shows that N. salsuginisUNG contains a salt bridge network that plays an important role in DNA backbone interactions. Disruption of the amino acid residues involved in the salt bridges greatly impedes the enzymatic activity. A tyrosine residue in motif 1 (GQDPY) is one of the distinct sequence features setting family 1 UNG apart from other families. The crystal structure of Y81G mutant indicates that several subtle changes may account for its inactivity. Unlike the conventional family 1 UNG enzymes, N. salsuginisUNG is not inhibited by Ugi, a potent inhibitor specific for family 1 UNG. This study underscores the diversity of paths that a uracil DNA glycosylase may take to acquire its unique structural and biochemical properties during evolution.DatabaseStructure data are available in the PDB under accession numbers 5X3G and 5X3H.

| S-EPMC5716868 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data