Multiple Factors Insulate Msh2-Msh6 Mismatch Repair Activity from Defects in Msh2 Domain I

JOURNAL OF MOLECULAR BIOLOGY

卷:411

Article

Kumar, Charanya¹  Piacente, Sarah C.¹  Sibert, Justin²  Bukata, Andrew R.¹  O'Connor, Jaime¹  Alani, Eric²  Surtees, Jennifer A.¹ 

[1] SUNY Buffalo, Dept Biochem, Sch Med & Biomed Sci, Buffalo, NY 14214 USA

[2] Cornell Univ, Dept Mol Biol & Genet, Ithaca, NY 14853 USA

关键词: mismatch repair;    Msh2-Msh6;    mutator phenotype;    hereditary non-polyposis colorectal cancer;    Saccharomyces cerevisiae;   

DOI  :  10.1016/j.jmb.2011.06.030

来源: Elsevier

【 摘 要 】

DNA mismatch repair (MMR) is a highly conserved mutation avoidance mechanism that corrects DNA polymerase misincorporation errors. In initial steps in MMR, Msh2-Msh6 binds mispairs and small insertion/deletion loops, and Msh2-Msh3 binds larger insertion/deletion loops. The msh2 Delta 1 mutation, which deletes the conserved DNA-binding domain I of Msh2, does not dramatically affect Msh2-Msh6-dependent repair. In contrast, msh2 Delta 1 mutants show strong defects in Msh2-Msh3 functions. Interestingly, several mutations identified in patients with hereditary nonpolyposis colorectal cancer map to domain I of Msh2; none have been found in MSH3. To understand the role of Msh2 domain I in MMR, we examined the consequences of combining the msh2 Delta 1 mutation with mutations in two distinct regions of MSH6 and those that increase cellular mutational load (pol3-01 and rad27). These experiments reveal msh2 Delta 1-specific phenotypes in Msh2-Msh6 repair, with significant effects on mutation rates. In vitro assays demonstrate that msh2 Delta 1-Msh6 DNA binding is less specific for DNA mismatches and produces an altered footprint on a mismatch DNA substrate. Together, these results provide evidence that, in vivo, multiple factors insulate MMR from defects in domain I of Msh2 and provide insights into how mutations in Msh2 domain I may cause hereditary nonpolyposis colorectal cancer. (C) 2011 Elsevier Ltd. All rights reserved.

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