Contribution of Msh2 and Msh6 Subunits to the Asymmetric ATPase and DNA Mismatch Binding Activities of Saccharomyces cerevisiae Msh2–Msh6 Mismatch Repair Protein

Authors

Edwin Antony, Marquette UniversityFollow
Sapna Khubchandani, Wesleyan University
Siying Chen, Wesleyan University
Manju M. Hingorani, Wesleyan University

Document Type

Article

Language

eng

Format of Original

10 p.

Publication Date

2-2006

Publisher

Elsevier

Source Publication

DNA Repair

Source ISSN

1568-7864

Abstract

Previous analyses of both Thermus aquaticus MutS homodimer and Saccharomyces cerevisiae Msh2–Msh6 heterodimer have revealed that the subunits in these protein complexes bind and hydrolyze ATP asymmetrically, emulating their asymmetric DNA binding properties. In the MutS homodimer, one subunit (S₁) binds ATP with high affinity and hydrolyzes it rapidly, while the other subunit (S₂) binds ATP with lower affinity and hydrolyzes it at an apparently slower rate. Interaction of MutS with mismatched DNA results in suppression of ATP hydrolysis at S₁—but which of these subunits, S₁ or S₂, makes specific contact with the mismatch (e.g., base stacking by a conserved phenylalanine residue) remains unknown. In order to answer this question and to clarify the links between the DNA binding and ATPase activities of each subunit in the dimer, we made mutations in the ATPase sites of Msh2 and Msh6 and assessed their impact on the activity of the Msh2–Msh6 heterodimer (in Msh2–Msh6, only Msh6 makes base specific contact with the mismatch). The key findings are: (a) Msh6 hydrolyzes ATP rapidly, and thus resembles the S₁ subunit of the MutS homodimer, (b) Msh2 hydrolyzes ATP at a slower rate, and thus resembles the S₂ subunit of MutS, (c) though itself an apparently weak ATPase, Msh2 has a strong influence on the ATPase activity of Msh6, (d) Msh6 binding to mismatched DNA results in suppression of rapid ATP hydrolysis, revealing a “cis” linkage between its mismatch recognition and ATPase activities, (e) the resultant Msh2–Msh6 complex, with both subunits in the ATP-bound state, exhibits altered interactions with the mismatch.

Comments

Accepted version. DNA Repair, Vol. 5, No. 2 (February 2006): 153-162. DOI. © 2006 Elsevier. Used with permission.

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

Recommended Citation

Antony, Edwin; Khubchandani, Sapna; Chen, Siying; and Hingorani, Manju M., "Contribution of Msh2 and Msh6 Subunits to the Asymmetric ATPase and DNA Mismatch Binding Activities of Saccharomyces cerevisiae Msh2–Msh6 Mismatch Repair Protein" (2006). Biological Sciences Faculty Research and Publications. 415.
https://epublications.marquette.edu/bio_fac/415