Bsmutl Model Summary

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The overall purpose of the study was to create a model based off the crystal structure of the endonuclease domain of Bacillus subtilis MutL. This structure, in particular, exposes the presence of zinc in the binding site which is important for the MMR function of BsMutL in vivo. From there, they proposed a model describing the association of MutS and DNA polymerase III, β clamp with MutL, and nicking of a synthesized DNA strand. The importance of MutL is in its united effort with MutS to recognize mismatches and interactions of the β clamp - these correlate with the polymerases ability to catalyze consecutive reactions without releasing the substrate. The combined effort could allow MutL to signal nicking of a newly synthesized DNA strand. …show more content…
These forms were obtained by amplifying the DNA and cloning it. Next, purification was completed using size exclusion and ion exchange chromatography. Crystallization concluded their methods as they resulted with three crystals. The structure of crystal form 1 has good resolution of 2.50 Å. Additionally, the R factor is 21.7% which still classifies it as good. The Rfree value is 26.8%; it’s slightly high but still within 5% of the R factor so it’s considered good. The outliers are not given, however, based off the data given still deems it a good structure. Crystal form 2 has a resolution of 2.0Å which is considered excellent/good structure. Furthermore, it has an R factor of 19.1% and an Rfree value of 22.8% - both considered excellent. Lastly, crystal 3 has a resolution of 2.3Å – this is deemed as good. The R factor is 21.4% and the Rfree value is 26.9% - both are considered good. The data just discussed allows us to infer that the atomic structure correctly reflects the structure of the protein. This validates the accuracy of the results …show more content…
When zinc was added to crystal 1, there was only 1 structure and no zinc seen. Crystal 2 had a small amount of zinc added to the buffer that the protein was in. The result was a little bit of change in shape and the zinc didn’t bind completely, therefore, it was difficult to see. Crystal 3 had even more zinc added to the crystallization solution. The outcome consisted of an even larger shape change as well as visibility of zinc bound. From this experiment, they learned that the zinc and the structural site help binding by locking the orientation between the dimerization and regulatory subdomains. Without such, whether it orients correctly or not is highly

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