DNA Mismatch Coupling
By identifying the replication error, fix, mismatch repair (MMR), which improves the fidelity of DNA replication. Is an important component of the MMR and DNA replication, speed and their mechanism to participate in the MMR is still unknown bracket of processing power. We found that to examine the role of processing power clamp DnaN Bacillus subtilis, which functions as a platform for connecting the repair replication of DNA and mismatch detection. By visualizing the fluorescent fusion of the in vivo function of the MutS, MutS form of lesions of the (ie Repurisomu) gap detection site of replication is found independently we. By directing the search to a nascent DNA, MutS focus of this is directed that non-compliance of any assistance, and pliers to Repurisomu area DnaN. Repurisomu, MutS after release, you open the mismatch from easily repaired. I found that we test the functional importance of DnaN mediated mismatch detection MMR, it constitutes 90% of the repair. This high dependence DnaN can be avoided by increasing the concentration of MutS in the cell that shows the average mode of detection of the in vivo that MutS of identification contradiction directly without mixing of Repurisomu. Overall, our results provide a couple mismatch recognition of new insights DnaN mechanism of DNA replication in living cells.
In eukaryotes is associated with the DNA replication temporarily mismatch repair (MMR), it is not clear how strand-specific MMR Whether is directed. We fused the Saccharomyces cerevisiae MSH6 and cyclin to limit the presence of the G2 / M phase of the cell cycle or S phase or MSH2, MSH6 mismatch recognition complex. While there is a defect in MSH6-G2 / M cyclin synthesis cyclin synthesis of MSH6-S, is an attempt to suppress the variation of the three loci replicated in mid-S phase. However, the functional MMR, MSH6-G2 / M cyclin fusion is a slow printing area very genome. In contrast to the hetero functionality of the recombinant MMR rejection at the time it is partially functional during both the G2 / M phase and S phase. These results connection MMR temporary indicates the rejection of the hetero DNA replication.
MMR mechanism, has been the subject of much discussion. It is not on the experimental results of the controversy surrounding the trans mechanism cis and save MMR system and many bacteria. There is a consensus biochemical properties of protein MMR considerably. Instead, the discussion will focus on the interpretation, I explained the mechanism of MMR biologically relevant experimental results. The cis initial model, they evidence the spiral does not appear but, MMR proteins are said to be able to form a nucleoprotein filament mismatch DNA to the start site. For the other models, was affected by the fact that ATP and mispairs distinction as (MutS MSHS, of homology) homologue of eukaryotic and CIS MMR Hano MutS. Mispair the MSHS and MutS challenge bound in ATP is able to capture containing DNA from end blocks of DNA indicates that occur in the dissociation DNA helix by pairing erroneous. This score is interpreted as aggressive move on the similarity of previous type I and III of the restriction enzyme.
MutS, however, the hydrolysis of ATP to give ADP-bound form that MutSβ is bound to subjected to hydrolysis of ATP-driven translocation (MSH2-MSH3 hetero eukaryotic) and (MSH2, MSH6 hetero eukaryotic) MutSα that it is not degraded mismatch is apparent. Instead after causing structural changes slidably in DNA, bound in the bound MutS mismatch hydrolysis ATP,. ATP was predicted to act as a cofactor to induce a conformational change of the specific Thus, to obtain such a structure pinch on the basis of a comparison of the structure of the ATP-ase RAD50 and MutS structure of ADP bound. This mechanism is possible to load the MutS dimer some dimer thereof, for example, DNA is through four interface to produce a DNA sequence such as that these observations may be interacting Te (MutS the required initial stages of ATP hydrolysis, hydrolysis-driven rotation) does not occur. The tetramer MutS and of, but not be able to mediate the DNA helix of communication, without the need especially for MMR, the structure of this type, report of four for MSH of complex eukaryotes.
Emphasize that it is the subject of MutS / Mutl with Mutl association with a long residence time in mispairs in MutS of ATP-challenging complex ATP load state of MutS of unlike models of MMR transformer. The mismatch, come from the analysis of the activation disgruntled there was a reaction in which the substrate has been hemi GATC, the first evidence of the transformer model, second most effective if both sites are the same criteria . It can be interpreted as a failure of the reaction absent Mutl assembly models only sliding transformer of MutS. The ease with MutS relative sliding can be also not a substrate access to naked DNA, blocking, there is a potential problem. Complex eukaryotic or their equivalents MutS Mutl / a, despite the fact that this is resistant to sliding. , Also, MutSαMSH2 complex of MMR-deficient mutant dominant – it retains the ability to assemble (MLH1, PMS1 Saccharomyces cerevisiae) the MutLα, and emphasizes the importance of the sliding But MSH6-G1142D failure sliding.
I tested an important aspect that distinguishes the model of trans and cis direct Modri ch and Pluciennik: requirement of the DNA helix and block continuous. In one experiment, they show that the binding of EcoRI to reduce the inactive mutant catalytically into the EcoRI recognition site located between the hemi GATC site mating erroneous, but depends mismatches Muth activation does not eliminate. It is suppressed due to the fact that it is not possible binding proteins firmly take 100% and attachment time of the place even in complete absence of the reaction. In the second experiment, and is used for double strand breaks to eliminate completely Muth activated and ends at a short distance between the hemi GATC plasmid mismatched. The results of a simple experiment these elegant, fall at a right angle to the cis-activation mechanism Chelsea side.