PMID: 12419246 , Related PDB id: 1MR1

Authors:

Wu JW, Krawitz AR, Chai J, Li W, Zhang F, Luo K, Shi Y

Title:

Structural mechanism of Smad4 recognition by the nuclear oncoprotein Ski: insights on Ski-mediated repression of TGF-beta signaling.

Journal:

Cell. 2002 Nov 1;111(3):357-67.

Abstract:

The Ski family of nuclear oncoproteins represses TGF-beta signaling through interactions with the Smad proteins. The crystal structure of the Smad4 binding domain of human c-Ski in complex with the MH2 domain of Smad4 reveals specific recognition of the Smad4 L3 loop region by a highly conserved interaction loop (I loop) from Ski. The Ski binding surface on Smad4 significantly overlaps with that required for binding of the R-Smads. Indeed, Ski disrupts the formation of a functional complex between the Co- and R-Smads, explaining how it could lead to repression of TGF-beta, activin, and BMP responses. Intriguingly, the structure of the Ski fragment, stabilized by a bound zinc atom, resembles the SAND domain, in which the corresponding I loop is responsible for DNA binding.