Asymmetric ATP Binding and Hydrolysis Activity of the Thermus aquaticus MutS Dimer Is Key to Modulation of Its Interactions with Mismatched DNA

Authors

Edwin Antony, Marquette UniversityFollow
Manju M. Hingorani, Wesleyan University

Document Type

Article

Language

eng

Format of Original

14 p.

Publication Date

10-2004

Publisher

American Chemical Society

Source Publication

Biochemistry

Source ISSN

0006-2960

Abstract

Prokaryotic MutS and eukaryotic Msh proteins recognize base pair mismatches and insertions or deletions in DNA and initiate mismatch repair. These proteins function as dimers (and perhaps higher order oligomers) and possess an ATPase activity that is essential for DNA repair. Previous studies of Escherichia coli MutS and eukaryotic Msh2−Msh6 proteins have revealed asymmetry within the dimer with respect to both DNA binding and ATPase activities. We have found the Thermus aquaticus MutS protein amenable to detailed investigation of the nature and role of this asymmetry. Here, we show that (a) in a MutS dimer one subunit (S1) binds nucleotide with high affinity and the other (S2) with 10-fold weaker affinity, (b) S1 hydrolyzes ATP rapidly while S2 hydrolyzes ATP at a 30−50-fold slower rate, (c) mismatched DNA binding to MutS inhibits ATP hydrolysis at S1 but slow hydrolysis continues at S2, and (d) interaction between mismatched DNA and MutS is weakened when both subunits are occupied by ATP but remains stable when S1 is occupied by ATP and S2 by ADP. These results reveal key MutS species in the ATPase pathway; S1_ADP−S2_ATP is formed preferentially in the absence of DNA or in the presence of fully matched DNA, while S1_ATP−S2_ATP and S1_ATP−S2_ADP are formed preferentially in the presence of mismatched DNA. These MutS species exhibit differences in interaction with mismatched DNA that are likely important for the mechanism of MutS action in DNA repair.

Comments

Accepted version. Biochemistry, Vol. 43, No. 41 (October 2004): 13115–13128. DOI. © 2004 American Chemical Society Publications. Used with permission.

Edwin Antony was affiliated with Wesleyan University at time of publication.

Recommended Citation

Antony, Edwin and Hingorani, Manju M., "Asymmetric ATP Binding and Hydrolysis Activity of the Thermus aquaticus MutS Dimer Is Key to Modulation of Its Interactions with Mismatched DNA" (2004). Biological Sciences Faculty Research and Publications. 413.
https://epublications.marquette.edu/bio_fac/413