ATP-dependent assembly of a ternary complex consisting of a DNA mismatch and the yeast MSH2-MSH6 and MLH1-PMS1 protein complexes

• Published in: The Journal of biological chemistry Vol. 273; no. 16; pp. 9837 - 9841
• Main Authors: Habraken, Y, Sung, P, Prakash, L, Prakash, S
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 17.04.1998
• Subjects: Adenosine Triphosphate - metabolism; ADN; ATP; Base Composition; Base Sequence; BINDING; BINDING PROTEINS; Binding Sites; Carrier Proteins; DEFAUT; DEFECTOS; DEFECTS; DNA; DNA CONFORMATION; DNA REPAIR; DNA, Fungal - chemistry; DNA, Fungal - metabolism; DNA-Binding Proteins - chemistry; DNA-Binding Proteins - isolation & purification; DNA-Binding Proteins - metabolism; Fungal Proteins - chemistry; Fungal Proteins - isolation & purification; Fungal Proteins - metabolism; INTERACTIONS; Molecular Sequence Data; MutL Proteins; MutS Homolog 2 Protein; Protein Binding; PROTEINAS AGLUTINANTES; PROTEINE DE LIAISON; SACCHAROMYCES CEREVISIAE; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.273.16.9837

MSH2 and MSH6 proteins exist as a stable complex, as do the MLH1 and PMS1 proteins. To study the mismatch binding properties of the MSH2-MSH6 complex and to examine its functional interaction with the MLH1-PMS1 complex, these protein complexes were purified to near homogeneity from overproducing yeast strains. As has been reported previously, the purified MSH2-MSH6 complex binds DNA substrates containing a G/T mismatch and insertion/deletion mismatches, but the binding affinity for the latter decreases as the size of the extrahelical loop increases. Addition of ATP or the nonhydrolyzable ATPγS reduces binding of the MSH2-MSH6 complex to the DNA substrates markedly. Here, we show that MSH2-MSH6 forms a ternary complex with MLH1-PMS1 on a mismatch containing DNA substrate. The formation of this ternary complex requires ATP, which can be substituted by ATPγS, suggesting that ATP binding alone is sufficient for ternary complex formation. Thus, it appears that ATP binding by the MSH2-MSH6 complex induces a conformation that is conducive for the interaction with MLH1-PMS1 complex, leading to the formation of the ternary complex.