Search results
Results from the WOW.Com Content Network
Uracil DNA glycosylase flips a uracil residue out of the duplex, shown in yellow. DNA glycosylases are responsible for initial recognition of the lesion. They flip the damaged base out of the double helix, as pictured, and cleave the N-glycosidic bond of the damaged base, leaving an AP site. There are two categories of glycosylases ...
After a mutation occurs, the mutagenic threat of uracil propagates through any subsequent DNA replication steps. [6] Once unzipped, mismatched guanine and uracil pairs are separated, and DNA polymerase inserts complementary bases to form a guanine-cytosine (GC) pair in one daughter strand and an adenine-uracil (AU) pair in the other. [7]
Uracil-DNA glycosylases are DNA repair enzymes that excise uracil residues from DNA by cleaving the N-glycosydic bond, initiating the base excision repair pathway. Uracil in DNA can arise either through the deamination of cytosine to form mutagenic U:G mispairs, or through the incorporation of dUMP by DNA polymerase to form U:A pairs. [18]
UNG is known to be the major player in uracil removal but when depleted SMUG1 can provide a backup for UNG in the antibody diversification process. [11] [12] In addition to uracil, SMUG1 removes several pyrimidine oxidation products. [13] and has a specific function to remove the thymine oxidation product 5-hydroxymethyl uracil from DNA. [14]
Structure of the base-excision repair enzyme uracil-DNA glycosylase excising a hydrolytically-produced uracil residue from DNA. The uracil residue is shown in yellow. When only one of the two strands of a double helix has a defect, the other strand can be used as a template to guide the correction of the damaged strand.
The small, excised, damage-containing DNA (sedDNA) oligonucleotides are initially released from the duplex in complex with TFIIH but then dissociate in an ATP-dependent manner and become bound to replication protein A (RPA). Inhibition of gap filling DNA synthesis and ligation results in an accumulation of RPA-bound sedDNAs in the cell.
Multiple DNA polymerases take on different roles in the DNA replication process. In E. coli, DNA Pol III is the polymerase enzyme primarily responsible for DNA replication. It assembles into a replication complex at the replication fork that exhibits extremely high processivity, remaining intact for the entire replication cycle.
Uracil-DNA glycosylase excises uracil bases from double-stranded DNA. This enzyme would therefore recognize and cut out both types of uracil – the one incorporated naturally, and the one formed due to cytosine deamination, which would trigger unnecessary and inappropriate repair processes. [14] This problem is believed to have been solved in ...