title: Study of interaction between Smad7 and DNA by single-molecule force spectroscopy.
abstract: Smad7 is an antagonist of TGF-beta signaling pathway and the mechanism of its inhibitory effect is of great interest. We recently found that Smad7 could function in the nucleus by binding to the DNA elements containing the minimal Smad binding element CAGA box. In this work, we further applied single-molecule force spectroscopy to study the DNA-binding property of Smad7. Smad7 showed similar binding strength to the oligonucleotides corresponding to the CAGA-containing activin responsive element (ARE) and the PAI-1 promoter, as that of Smad4. However, Smad7 also exhibited a binding activity to the mutant ARE with the CAGA sequence substituted, indicating its DNA-binding specificity is different from other Smads. Moreover, we demonstrated that the MH2 domain of Smad7 had a higher binding affinity to the DNA elements than the full-length Smad7, while the N-terminal domain exhibited an inhibitory effect.
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Key Laboratory of Molecular Nanostructures and Nanotechnology, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Shi
authors.forename: Feng
authors.initials: F
authors.lastname: Chen
authors.forename: Junping
authors.initials: J
authors.lastname: Yu
authors.forename: Yongchun
authors.initials: Y
authors.lastname: Xu
authors.forename: Suping
authors.initials: S
authors.lastname: Zhang
authors.forename: Ye-Guang
authors.initials: YG
authors.lastname: Chen
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Fang
mesh_terms: D001483:Base Sequence; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D018625:Microscopy, Atomic Force; D017395:Plasminogen Activator Inhibitor 1 / Q000235:genetics; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D020218:Response Elements; D051906:Smad7 Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D017395:Plasminogen Activator Inhibitor 1; D051906:Smad7 Protein; D004247:DNA