Dynamics of MutS鈥揗ismatched DNA Complexes Are Predictive of Their Repair Phenotypes
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- 作者：Vanessa C. DeRocco ; Lauryn E. Sass ; Ruoyi Qiu ; Keith R. Weninger ; Dorothy A. Erie
- 刊名：Biochemistry
- 出版年：2014
- 出版时间：April 1, 2014
- 年：2014
- 卷：53
- 期：12
- 页码：2043-2052
- 全文大小：436K
- 年卷期：v.53,no.12(April 1, 2014)
- ISSN：1520-4995
文摘
MutS recognizes base鈥揵ase mismatches and base insertions/deletions (IDLs) in newly replicated DNA. Specific interactions between MutS and these errors trigger a cascade of protein鈥損rotein interactions that ultimately lead to their repair. The inability to explain why different DNA errors are repaired with widely varying efficiencies in vivo remains an outstanding example of our limited knowledge of this process. Here, we present single-molecule F枚rster resonance energy transfer measurements of the DNA bending dynamics induced by Thermus aquaticus MutS and the E41A mutant of MutS, which is known to have error specific deficiencies in signaling repair. We compared three DNA mismatches/IDLs (T-bulge, GT, and CC) with repair efficiencies ranging from high to low. We identify three dominant DNA bending states [slightly bent/unbent (U), intermediately bent (I), and significantly bent (B)] and find that the kinetics of interconverting among states varies widely for different complexes. The increased stability of MutS鈥搈ismatch/IDL complexes is associated with stabilization of U and lowering of the B to U transition barrier. Destabilization of U is always accompanied by a destabilization of B, supporting the suggestion that B is a 鈥渞equired鈥?precursor to U. Comparison of MutS and MutS-E41A dynamics on GT and the T-bulge suggests that hydrogen bonding to MutS facilitates the changes in base鈥揵ase hydrogen bonding that are required to achieve the U state, which has been implicated in repair signaling. Taken together with repair propensities, our data suggest that the bending kinetics of MutS鈥搈ismatched DNA complexes may control the entry into functional pathways for downstream signaling of repair.