AlkB homolog 1, histone H2A dioxygenase is a protein that in humans is encoded by the ALKBH1 gene. [5]
AlkB homolog 1, histone H2A dioxygenase is a protein that in humans is encoded by the ALKBH1 gene. [5]
This gene encodes a homolog to the E. coli alkB gene product. The E. coli alkB protein is part of the adaptive response mechanism of DNA alkylation damage repair. It is involved in damage reversal by oxidative demethylation of 1-methyladenine and 3-methylcytosine. [provided by RefSeq, Jul 2008].
The CpG sites or CG sites are regions of DNA where a cytosine nucleotide is followed by a guanine nucleotide in the linear sequence of bases along its 5' → 3' direction. CpG sites occur with high frequency in genomic regions called CpG islands.
DNA glycosylases are a family of enzymes involved in base excision repair, classified under EC number EC 3.2.2. Base excision repair is the mechanism by which damaged bases in DNA are removed and replaced. DNA glycosylases catalyze the first step of this process. They remove the damaged nitrogenous base while leaving the sugar-phosphate backbone intact, creating an apurinic/apyrimidinic site, commonly referred to as an AP site. This is accomplished by flipping the damaged base out of the double helix followed by cleavage of the N-glycosidic bond.
Base excision repair (BER) is a cellular mechanism, studied in the fields of biochemistry and genetics, that repairs damaged DNA throughout the cell cycle. It is responsible primarily for removing small, non-helix-distorting base lesions from the genome. The related nucleotide excision repair pathway repairs bulky helix-distorting lesions. BER is important for removing damaged bases that could otherwise cause mutations by mispairing or lead to breaks in DNA during replication. BER is initiated by DNA glycosylases, which recognize and remove specific damaged or inappropriate bases, forming AP sites. These are then cleaved by an AP endonuclease. The resulting single-strand break can then be processed by either short-patch or long-patch BER.
Activation-induced cytidine deaminase, also known as AICDA, AID and single-stranded DNA cytosine deaminase, is a 24 kDa enzyme which in humans is encoded by the AICDA gene. It creates mutations in DNA by deamination of cytosine base, which turns it into uracil. In other words, it changes a C:G base pair into a U:G mismatch. The cell's DNA replication machinery recognizes the U as a T, and hence C:G is converted to a T:A base pair. During germinal center development of B lymphocytes, error-prone DNA repair following AID action also generates other types of mutations, such as C:G to A:T. AID is a member of the APOBEC family.
The adaptive response is a DNA damage response pathway prevalent across bacteria that protects DNA from damage by external agents or by errors during replication. It is initiated specifically against alkylation, particularly methylation, of guanine or thymine nucleotides or phosphate groups on the sugar-phosphate backbone of DNA. Under sustained exposure to low-level treatment with alkylating mutagens, bacteria can adapt to the presence of the mutagen, rendering subsequent treatment with high doses of the same agent less effective.
AlkB (Alkylation B) is a protein found in E. coli, induced during an adaptive response and involved in the direct reversal of alkylation damage. AlkB specifically removes alkylation damage to single stranded (SS) DNA caused by SN2 type of chemical agents. It efficiently removes methyl groups from 1-methyl adenines, 3-methyl cytosines in SS DNA. AlkB is an alpha-ketoglutarate-dependent hydroxylase, a superfamily non-haem iron-containing proteins. It oxidatively demethylates the DNA substrate. Demethylation by AlkB is accompanied with release of CO2, succinate, and formaldehyde.
DNA-(apurinic or apyrimidinic site) lyase is an enzyme that in humans is encoded by the APEX1 gene.
The enzyme DNA-(apurinic or apyrimidinic site) lyase, also referred to as DNA-(apurinic or apyrimidinic site) 5'-phosphomonoester-lyase or DNA AP lyase catalyzes the cleavage of the C-O-P bond 3' from the apurinic or apyrimidinic site in DNA via β-elimination reaction, leaving a 3'-terminal unsaturated sugar and a product with a terminal 5'-phosphate. In the 1970s, this class of enzyme was found to repair at apurinic or apyrimidinic DNA sites in E. coli and in mammalian cells. The major active enzyme of this class in bacteria, and specifically, E. coli is endonuclease type III. This enzyme is part of a family of lyases that cleave carbon-oxygen bonds.
Uracil-DNA glycosylase is an enzyme. Its most important function is to prevent mutagenesis by eliminating uracil from DNA molecules by cleaving the N-glycosidic bond and initiating the base-excision repair (BER) pathway.
DNA polymerase lambda, also known as Pol λ, is an enzyme found in all eukaryotes. In humans, it is encoded by the POLL gene.
Cyclin-O is a protein that in humans is encoded by the CCNO gene.
Single-strand selective monofunctional uracil DNA glycosylase is an enzyme that in humans is encoded by the SMUG1 gene. SMUG1 is a glycosylase that removes uracil from single- and double-stranded DNA in nuclear chromatin, thus contributing to base excision repair.
In DNA repair, the Ada regulon is a set of genes whose expression is essential to adaptive response, which is triggered in prokaryotic cells by exposure to sub-lethal doses of alkylating agents. This allows the cells to tolerate the effects of such agents, which are otherwise toxic and mutagenic.
Tet methylcytosine dioxygenase 2 (TET2) is a human gene. It resides at chromosome 4q24, in a region showing recurrent microdeletions and copy-neutral loss of heterozygosity (CN-LOH) in patients with diverse myeloid malignancies.
DNA oxidative demethylase (EC 1.14.11.33, alkylated DNA repair protein, alpha-ketoglutarate-dependent dioxygenase ABH1, alkB (gene)) is an enzyme with systematic name methyl DNA-base, 2-oxoglutarate:oxygen oxidoreductase (formaldehyde-forming). This enzyme catalyses the following chemical reaction
The human KDM2B gene encodes the protein lysine (K)-specific demethylase 2B.
Alpha-ketoglutarate-dependent hydroxylases are a major class of non-heme iron proteins that catalyse a wide range of reactions. These reactions include hydroxylation reactions, demethylations, ring expansions, ring closures, and desaturations. Functionally, the αKG-dependent hydroxylases are comparable to cytochrome P450 enzymes. Both use O2 and reducing equivalents as cosubstrates and both generate water.
AlkB homolog 3, alpha-ketoglutaratedependent dioxygenase is a protein that in humans is encoded by the ALKBH3 gene.
RNA demethylase ALKBH5 is a protein that in humans is encoded by the ALKBH5 gene.
Tet methylcytosine dioxygenase 3 is a protein that in humans is encoded by the TET3 gene.
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This article incorporates text from the United States National Library of Medicine, which is in the public domain.