title: Chimeric Saccharomyces cerevisiae Msh6 protein with an Msh3 mispair-binding domain combines properties of both proteins.
abstract: Msh2-Msh3 and Msh2-Msh6 are two partially redundant mispair-recognition complexes that initiate mismatch repair in eukaryotes. Crystal structures of the prokaryotic homolog MutS suggest the mechanism by which Msh6 interacts with mispairs because key mispair-contacting residues are conserved in these two proteins. Because Msh3 lacks these conserved residues, we constructed a series of mutants to investigate the requirements for mispair interaction by Msh3. We found that a chimeric protein in which the mispair-binding domain (MBD) of Msh6 was replaced by the equivalent domain of Msh3 was functional for mismatch repair. This chimera possessed the mispair-binding specificity of Msh3 and revealed that communication between the MBD and the ATPase domain is conserved between Msh2-Msh3 and Msh2-Msh6. Further, the chimeric protein retained Msh6-like properties with respect to genetic interactions with the MutL homologs and an Msh2 MBD deletion mutant, indicating that Msh3-like behaviors beyond mispair specificity are not features controlled by the MBD.
authors.affiliation: Ludwig Institute for Cancer Research, Departments of Medicine and Cellular and Molecular Medicine, and Cancer Center, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0669, USA.
authors.forename: Scarlet S
authors.initials: SS
authors.lastname: Shell
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Putnam
authors.forename: Richard D
authors.initials: RD
authors.lastname: Kolodner
mesh_terms: D020137:Base Pair Mismatch; D001665:Binding Sites / Q000235:genetics; D017124:Conserved Sequence; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000502:physiology; D005656:Fungal Proteins / Q000235:genetics* / Q000502:physiology; D051718:MutS Homolog 2 Protein / Q000235:genetics* / Q000502:physiology; D016297:Mutagenesis, Site-Directed; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000502:physiology
chemical_list: D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C098790:MSH6 protein, S cerevisiae; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D051718:MutS Homolog 2 Protein