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PARP1 takes part in the base excision repair pathway, by catalyzing the poly ADP-ribosyl of a restricted number of acceptor proteins involved in chromatin architecture and in DNA metabolism.. PARP1 mediates the poly ADP-ribosy of APLF and CHFR. PARP1 positively regulates the transcription of MTUS1 and negatively regulates the transcription of MTUS2/TIP150. PARP1 is a chromatin-associated enzyme, poly (ADP-ribosyl) transferase, which modifies various nuclear proteins by poly ADP-ribosyl. PARP1 takes part in the regulation of various significant cellular processes such as differentiation, proliferation, and tumor transformation and also in the regulation of the molecular events involved in the recovery of cell from DNA damage. PARP1 is a site of mutation in Fanconi anemia, and is involved in the pathophysiology of type I diabetes.

TAF10 is a small subunit of TFIID which is related to a subdivision of TFIID complexes. Studies with human and mammalian cells verified that this subunit is mandatory for transcriptional activation by the estrogen receptor, for progression through the cell cycle, and is essential for several cellular differentiation programs.

CTDSP1 is a class 2C phosphatase with activity dependent on the conserved DxD motif. CTDSP1 preferentially catalyzes the dephosphorylation of 'Ser-5' within the tandem 7 residues repeats in the C-terminal domain (CTD) of the largest RNA polymerase II subunit POLR2A. In addition, CTDSP1 negatively regulates RNA polymerase II transcription, possibly by controlling the transition from initiation/capping to processive transcript elongation.

DNA-3-methyladenine glycosylase (MPG) is a member of the DNA glycosylase MPG family. MPG initiates base excision repair in DNA by removing a wide variety of alkylated, deaminated, and lipid peroxidation-induced purine adducts.

Single-strand-selective monofunctional uracil-DNA glycosylase (SMUG1) is an enzyme responsible for recognizing base lesions in the genome and initiating base excision DNA repair. SMUG1 participates in base excision repair by removing uracil from single- and double-stranded DNA. SMUG1 serves as a monofunctional DNA glycosylase specific for uracil (U) residues in DNA and has inclination for single-stranded DNA substrates. SMUG1 activity is greater against mismatches (U/G) than against matches (U/A).

Polymerase Delta 4 also known as POLD4 is the smallest subunit of DNA polymerase delta. DNA polymerase delta which takes a vital part in DNA replication and repair possesses both polymerase and 3' to 5' exonuclease activity. POLD4 increases the activity of DNA polymerase delta and takes a part in fork repair and stabilization during interactions with the DNA helicase Bloom syndrome protein. POLD4 contributes to PCNA-dependent activity of DNA polymerase delta.

MGMT is an enzyme that repairs O-6-methylguanine, a mutagenic DNA base damaged by endogenous and environmental alkylating agents and takes part in the cellular defense against the biological effects of O-6-methylguanine in DNA. MGMT repairs alkylated guanine in DNA by stoichiometrically transferring the alkyl group at the O-6 position to a cysteine residue in the enzyme. abnormal MGMT expression correlates with the prognosis in human solid cancers. MGMT decrease of expression is correlated with methylation. The human MGMT is a negative regulator of estrogen receptor-mediated transcription upon alkylation DNA damage. MGMT promoter hypermethylation plays an important role in the early steps of colorectal carcinogenesis. Abnormal promoter hypermethylation of MGMT gene is associated with oral squamous cell carcinomas.

OGG1 is a DNA glycosylase enzyme which takes part in base excision repair. OGG1 protein is the main enzyme accountable for the excision of 7,8-dihydro-8-oxoguanine (8-oxoG), a mutagenic base byproduct which arises as a result of exposure to reactive oxygen species (ROS). OGG1 shows beta lyase activity that nicks DNA 3'' to the lesion.

G/U mismatch-specific DNA glycosylase (mug) is a part of the TDG/mug DNA glycosylase family. Mug is necessary for DNA damage lesion repair in stationary-phase cells. Mug protein removes three N4-ethenocytosine and takes away s the uracil base from mismatches in the order of U:G>U:A. The enzyme Uracil-N-Glycosylase removes uracil from the DNA leaving an AP position. Mug is also able to hydrolyzing the carbon-nitrogen bond among the sugar-phosphate backbone of the DNA and the mispaired base. The complementary strand guanine plays a role in substrate recognition.

Uracil DNA glycosylase (UDG), or uracil-DNA glycosylase 1, is a crucial enzyme found in all life forms, involved in repairing damaged DNA by specifically removing uracil bases that are misincorporated into DNA during replication or deaminated cytosine. In various organisms, UDG goes by different names, such as b2580, JW2564, EC 3.2.2.27, DGU, UNG15, HIGM5, EC 3.2.2, HIGM4, and UNG2. Here, we delve into the E. coli UDG, examining its structure, function, and applications in molecular biology.

Structure: The crystal structure of E. coli UDG has been extensively studied, revealing that it belongs to the uracil DNA glycosylase (UDG) superfamily. The E. coli UDG monomer has 229 amino acids with a molecular weight of 25 kDa. The protein has a beta-sheet-rich structure with an alpha-helix on one side and a groove on the other side that binds to DNA. The active site of E. coli UDG contains a conserved glutamic acid residue that acts as a catalytic base to facilitate the hydrolysis of the N-glycosidic bond between uracil and the sugar phosphate backbone.

Function: E. coli UDG plays a critical role in maintaining the integrity of the genome by preventing the accumulation of mutations that can arise from the incorporation of uracil into DNA. Uracil in DNA can occur spontaneously from the deamination of cytosine or can be incorporated during DNA synthesis when dUTP is used instead of dTTP. Unrepaired uracil bases can lead to DNA damage and genomic instability, possibly resulting in cell death or disease. E. coli UDG specifically recognizes and removes uracil bases from DNA, creating an abasic site that is further processed by other repair enzymes.

SSU72 is an extremely conserved homologue of yeast Ssu72, a CTD phosphatase and a component of the polyadenylation/termination machinery. SSU72 interacts with TFIIB, Rb and DNAM-1 and operates to catalyze the dephosphorylation of target proteins, and taking part in RNA processing and termination via dephosphorylation of Pol II. SSU72 is found in multiple alternatively spliced isoforms.

UNG is a member of the Uracil-DNA glycosylase family. One of his functions is to prevent mutagenesis by eliminating uracil from DNAmolecules by cleaving the N-glycosylic bond and initiating the base-excision repair (BER) pathway. Uracil basesare formed as a result of cytosine deamination or misincorporation of dUMP residues. After a mutation is formed, the mutagenicthreat of uracil propagates through any subsequent DNA replication steps. Among the diseases associated with UNG are: congenital rubella, and immunodeficiency with hyper igm type 4.

N-6 Adenine-Specific DNA Methyltransferase 1, also known as N6AMT1 is part of the methyltransferase family. N6AMT1 is implicated in the methylation of release factor I during translation termination. In addition, N6AMT1 is involved in converting the arsenic metabolite monomethylarsonous acid to the less toxic dimethylarsonic acid.

CRCP is a ubiquitous coupling protein for the calcitonin gene-related peptide and adrenomedullin receptors. CRCP controls ligand sensitivity in several tissues and has DNA-directed RNA polymerase activity, catalytic activity and calcitonin receptor activity.

MUTM is a base excision repair enzyme that identifies and eliminates a large variety of oxidized purines from correspondingly impaired DNA. MUTM is nondismissable and essential to remove quickly its substrate lesions on the chromosome. MUTM, additionally, mends a large number of the lesions recognized by Endo III, signifying that MUTM takes a prominent part in the overall repair of both purine damage and pyrimidine damage in vivo.

Deoxyribonuclease I Human Recombinant (rhDNase), an enzyme which selectively cleaves DNA. Recombinant Human Dnase is an endonuclease enzyme which splits phosphodiester linkages within polynucleotides, acting primarely on single stranded DNA (ssDNA), double stranded DNA (ddDNA) and chromatin. Dnase is activated by bivalent metals such as Mg+2 and Ca+2 .
Dnase enzymes are common reagents used in biochemical methods requiring diestion of DNA and recovery of RNA, or where DNA is to be removed without affecting structural proteins or enzymes. Dnase enzymes are also used in tissue culture to digest DNA from damaged cells, resulting in reduced viscosity, and for removal of membrane-bound DNA fragments.

Endonuclease 8-like 2 (NEIL2) is a member of a class of DNA glycosylases homologous to the bacterial Fpg/Nei family. These glycosylases set off the first step in base excision repair by cleaving bases damaged by reactive oxygen species and introducing a DNA strand break through the associated lyase reaction. NEIL2 is involved in base excision repair of DNA damaged by oxidation or by mutagenic agents. NEIL2 has DNA glycosylase activity towards 5-hydroxyuracil and other oxidized derivatives of cytosine with a preference for mismatched double stranded DNA (DNA bubbles). NEIL2 has insignificant or undetectable activity with 8-oxoguanine, thymine glycol, 2-hydroxyadenine, hypoxanthine, and xanthine. NEIL2 also has AP (apurinic/apyrimidinic) lyase activity and creates incisions in the DNA strand. NEIL2 cleaves the DNA backbone by beta-delta exclusion to produce a single-strand break at the site of the removed base with both 3'- and 5'-phosphates. NEIL2 is found in the testis, skeletal muscle, heart, brain, placenta, lung, pancreas, kidney and liver.

TREX2 holds a 3-prime-to-5-prime exonuclease activity and eliminates mismatched, modified, fragmented, and normal nucleotides to produce the appropriate 3-prime termini for following steps in the DNA metabolic pathways. TREX2 has a role in DNA replication, repair, and recombination.

E. coli UDG is a valuable tool in molecular biology research for its ability to remove uracil from DNA templates. This enzyme is widely used in various applications, including site-directed mutagenesis, PCR amplification, and sequencing. UDG can remove uracil from the template strand of a DNA duplex, enabling the introduction of specific mutations or the creation of nicked DNA for downstream applications. Additionally, UDG is used in PCR amplification to prevent the amplification of any residual uracil-containing templates, which can lead to false-positive results. UDG has also been used in sequencing applications to remove uracil from DNA templates before sequencing, improving the accuracy and reliability of the results.

Conclusion: E. coli UDG is a highly conserved enzyme that plays a crucial role in maintaining genomic integrity by removing uracil from DNA. The crystal structure of E. coli UDG has been extensively studied, revealing the conserved catalytic mechanism and the interaction of the protein with DNA. E. coli UDG is a valuable enzyme with numerous applications in molecular biology research and potential applications in the medical field, such as cancer treatment. More research is needed to fully understand the therapeutic potential of targeting UDG. Overall, E. coli UDG is a valuable enzyme with numerous applications in molecular biology research and potential applications in the medical field.

Adenine DNA glycosylase (mutY) is an adenine DNA glycosylase active on DNA substrates including A/G, A/8-oxoG, or A/C mismatches and also has a weak guanine glycosylase activity on G/8- oxoG-containing DNA. mutY is essential for the prevention of mutations resulting from oxidative DNA impairment. Rising levels of mutY in A549 cells exposed to oxygen and infrared radiation leads to improvements in cell survival. mutY is common in neurons where mitochondrial genomes exposed to reactive oxygen species that damage DNA must uphold integrity over the whole mammalian life span.

Endonuclease III (nth) is a DNA repair enzyme which has both DNA N-glycosylase activity and AP-lyase activity. The DNA N-glycosylase activity releases numerous damaged pyrimidines from DNA by cleaving the N-glycosidic bond and leaving an AP (apurinic/apyrimidinic) site. This AP-lyase activity cleaves the phosphodiester bond 3' to the AP site by a beta-elimination, thus leaving a 3'-terminal unsaturated sugar and a product with a terminal 5'-phosphate.

Thymine-DNA glycosylase (TDG) is a member of the TDG/mug DNA glycosylase family.
TDG is a nuclear protein that fixes G/T mismatches to G/C pairs by hydrolyzing the carbon-nitrogen bond between the sugar-phosphate backbone of the DNA and the mispaired thymin. In addition, TDG removes uracil and 5-bromouracil from mispairings with guanine. The TDG enzyme has an essential role in cellular defense against genetic mutation triggered by the spontaneous deamination of 5-methylcytosine and cytosine.

DNA toposisomerase I is a key nuclear enzyme that interconverts supercoiled DNA to the required topological conformations for normal DNA replication and transcription. This enzyme is the target antigen for the so-called Scl-70 autoantibodies. Scl-70 antibodies are a specific marker in Scleroderma patients (specificity 98-100%) and are associated with the presence of diffuse skin involvement and pulmonary fibrosis.
In human tissues the DNA topoisomerase I is initially synthesized as a protein with 100 kDa molecular weight. Most of this precursor is then proteolytically processed to a species with 70 kDa molecular weight from which the Scl-70 antigen has derived its name.