Crystal Structure of the TSP-1 Type 1 Repeats: A Novel Layered Fold and Its Biological Implication

Thrombospondin-1 (TSP-1) contains three type 1 repeats (TSRs), which mediate cell attachment, glycosaminoglycan binding, inhibition of angiogenesis, activation of TGFβ, and inhibition of matrix metalloproteinases. The crystal structure of the TSRs reported in this article reveals a novel, antiparallel, three-stranded fold that consists of alternating stacked layers of tryptophan and arginine residues from respective strands, capped by disulfide bonds on each end. The front face of the TSR contains a right-handed spiral, positively charged groove that might be the "recognition" face, mediating interactions with various ligands. This is the first high-resolution crystal structure of a TSR domain that provides a prototypic architecture for structural and functional exploration of the diverse members of the TSR superfamily.