The G·A mismatch

The biochemical tests, be efficiently repaired them less in the cells as compared to non-conformity because other has been shown, G · base pairs, is particularly interesting. Different configurations and four G · structure mismatch dominant, not characterized by NMR and X-ray crystallography. PH and salt concentration of the medium depends on the base stacking the exact format mismatch G. Various forms of G · mismatch because it represents another target for recognition, for this difference, enzyme repair of G · mismatch, raises a particular problem.

The G·A mismatch

Glioma cell lines of human 2 (O6-methylguanine-DNA methyltransferase is missing) gap various extracts from (ie, A1235-MR4 differential resistance and alkylation A1235) of the base model (45-BP were examined for their ability to perform the incision direction of) DNA. In one of the 3 mispairs, in the same place, with the exception of the presence, this hetero substrate is in the same order: human thymine and U. ATP: G: T, O6-methylguanine: T: G and (M6G T) supplemented with (TDG) DNA glycosylase, parent (A1235) extract, and competent action 5 ‘cut immediately, the three bases to uracil residues or mismatch thymine. (M6G or: T) T: the substrate is remarkable, while it decreased in the absence of ATP, G: potency of the extract to the A1235 G U substrate: only G Unlike this derived extracts under the same conditions as recognition U substrate irrelevant The addition of ATP to a, and is cleaved rapidly by extracts of both. Does not depend on ATP no T operations, effects and other ATP-dependent and effective: the combined data, these earlier studies we showed that human cells have two G Check the results, and extension.

Derivative extract lacks the activity of the former, but I retain the activity of the last. I inhibit the T-substrate itself U substrate ATP-dependent G: greater than T incision activity G: The study of substrate competition of G. Given the choice of the substrate is well known for G TDG, T-section machine in human cells:: U in comparison with G T, the result of this unexpected, and that TDG is an integral part of the ATP-dependent G and means you can be. Finally, to the mismatch G in 5 ‘G: Base provides A1235 extract sequence preference in the presence of TDG and ATP, mismatched T is the observation of the latter is preferred pudding much more (cytosine in particular) pyrimidine I show that ATP-dependent. It aims to repair the CpG islands methylation in T incision activity is associated with the control of deamination 5 methycytosine lesion gene expression: G.

G: T is, 5 – mispairs at the origin of the DNA by spontaneous deamination of methyl cytosine. Human cells K and the C pair of two strains of E: that has been restored mispairs such, the normal G. In this study, I analyzed the maintenance of human cell extract of G: DNA mismatch T in various contexts. We performed two sets of experiments. First, identification of the G in the sequence was a repair: mispairs are repaired in CpG sites in CpG sites different 4, T is, G: GPG was T-mismatch site. Cytosine hemimethylation does not lock the repair substrate comprising a CpG / GPT gap. The second series of experiments the substrate G: This is done G positional T mismatch mismatch, T, G, at the 5 ‘or C, the change in the complementary strand, to provide a thorough Watson-Crick pairing otherwise . All cut 5 ‘slight mismatch T, and competed repair G: is 5 “and mismatch G. Therefore T-substrate, human G C: the mismatch activity of T shows the incision sequence specificity to G: T mismatch rather than DNA specific sites, however. Incisable site to others, is affected by the base 5 ‘mismatch G. incision smaller pairs

DNA mismatch repair (MMR), is responsible for maintaining accurate DNA for replication. It captures errors in DNA strand newly synthesized is omitted to reduce the frequency of mutations by the factor 100 to 1000, from the polymerase adjustment. In humans, loss of alleles of any of the mismatch repair protein, one of the most common forms of cancer predisposition, thereby referred to as (HNPCC) Hereditary nonpolyposis colon cancer. The mismatch repair functional, recognition of the mismatch depends on the (MSH2/MSH3 or MSH2/MSH6) heterodimer in humans in the MutS protein homodimers of dimer in bacteria. To recognize tie and ATP incompatibility, you can activate the MutS Mutl protein signal search direction discrimination of second. Be removed after the signal (in one kilobytes apart) chain newly synthesized was detected, it was resynthesised.

Crystal structure of MutS of E. coli have been resolved. T mismatch DNA oligomer: Crystal grew MutS C800, C-terminus (53 amino acids) truncation, over in the presence of G. Structure was solved by a three-wavelength selenomethionine MAD experiment performed at the beam line BM14. The high-resolution data, I gathered in ID14-2 beam line from the same crystal.

Structure of the MutS dimer binds to mismatched DNA oligomer. The protein, whereas the N-terminal domain from a single monomer, mismatch probe includes a DNA having a non-specific binding domains of the two monomers. Therefore, this protein is present to explain the reasons for determining the contradiction that is bound to only one of the partners of hetero eukaryotic, as structural heterodimer. It is recognized by hydrogen bonding base, to putting phenylalanine contradiction bending DNA at mismatch site dramatically. MutS DNA recognition in the area of ​​the flexible, allows the entry of minor changes connections required to recognize mismatches all different.