Mammalian SMC3 C-terminal and Coiled-coil Protein Domains Specifically Bind Palindromic DNA, Do Not Block DNA Ends, and Prevent DNA Bending

• Published in: The Journal of biological chemistry 1999-12, Vol.274 (53), p.38216-38224
• Main Authors: Akhmedov, A T, Gross, B, Jessberger, R
• Format: Article
• Language: English
• Subjects: Animals; Base Sequence; Cattle; Cell Cycle Proteins - chemistry; Cell Cycle Proteins - genetics; Cell Cycle Proteins - metabolism; Chromosomal Proteins, Non-Histone - chemistry; Chromosomal Proteins, Non-Histone - genetics; Chromosomal Proteins, Non-Histone - metabolism; DNA - chemistry; DNA - metabolism; DNA Primers; DNA-Binding Proteins - chemistry; DNA-Binding Proteins - metabolism; Nucleic Acid Conformation; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; SMC1 protein; SMC3 protein
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.274.53.38216

The C-terminal domains of yeast structural maintenance of chromosomes (SMC) proteins were previously shown to bind double-stranded DNA, which generated the idea of the antiparallel SMC heterodimer, such as the SMC1/3 dimer, bridging two DNA molecules. Analysis of bovine SMC1 and SMC3 protein domains now reveals that not only the C-terminal domains, but also the coiled-coil region, binds DNA, while the N terminus is inactive. Duplex DNA and DNA molecules with secondary structures are highly preferred substrates for both the C-terminal and coiled-coil domains. Contrasting other cruciform DNA-binding proteins like HMG1, the SMC3 C-terminal and coiled-coil domains do not bend DNA, but rather prevent bending in ring closure assays. Phosphatase, exonuclease, and ligase assays showed that neither domain renders DNA ends inaccessible for other enzymes. These observations allow modifications of models for SMC-DNA interactions.