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MutS and DNA dynamics during mismatch recognition and repair.
Author(s) -
Sharma Anushi,
Hingorani Manju
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.lb80
Subject(s) - dna mismatch repair , thermus thermophilus , thermus aquaticus , dna , biophysics , chemistry , base pair , dna repair , microbiology and biotechnology , biology , biochemistry , dna polymerase , gene , escherichia coli
Mismatch repair (MMR) is essential for correcting base‐pairing errors in DNA. MutS protein recognizes mispaired bases in DNA and signals excision and resynthesis of the mismatched strand. The DNA binding and ATPase activities of MutS are under active investigation‐especially the transient events involved in mismatch recognition and initiation of repair. We utilize transient kinetic methods coupled with fluorescence spectroscopy to determine the mechanisms of action of Thermus aquaticus MutS. Our results indicate a two‐step DNA binding mechanism for MutS, wherein an initial rapid encounter establishes a weak binding equilibrium ( K D1 = 3 μM), followed by slow formation of a mismatch‐specific MutS‐DNA complex with the DNA in bent conformation ( k conf ~ 20 s −1 and K D2 = 5 nM). ATP binding to MutS‐DNA complex ( k ON = 0.3 μM −1 s −1 ) is followed by two slow steps involving conformational changes in MutS and the mismatch site in DNA (~ 2 s −1 ) followed by MutS release from the mismatch (~ 0.5 s −1 ). With detailed kinetic analysis, we are developing a comprehensive view of MutS actions on DNA, and gaining novel mechanistic insights into the mechanism of initiation of MMR.