Crystal Structure of the LG3 Domain of Endorepellin, an Angiogenesis Inhibitor

Endorepellin, the C-terminal region of perlecan, inhibits angiogenesis by disrupting actin cytoskeleton and focal adhesions. The C-terminal laminin-like globular domain (LG3) of endorepellin directs most of this antiangiogenic activity. To investigate the angiostatic mechanism and to identify structural determinants, we have solved crystal structures of the LG3 domain in both apo- and calcium-bound forms at resolutions of 1.5 Å and 2.8 Å, respectively. The conserved core has the jellyroll fold characteristic of LG domains. The calcium-induced structural changes seem very restricted, and the calcium binding site appears to be preformed, suggesting that the bound calcium ion, rather than structural rearrangements, contributes to antiangiogenesis. We have identified H4268 on the EF loop as a key residue for the biochemical function of LG3, since its mutation abolishes antiangiogenic activity, and mutant LG3 can no longer form a direct interaction with integrin. Taken together, we propose that these two distinct structural elements contribute to the angiostatic effect of endorepellin.

Graphical AbstractFigure optionsDownload high-quality image (129 K)Download as PowerPoint slideResearch Highlights
► Laminin-like globular (LG3) domain of endorepellin inhibits angiogenesis by disrupting actin cytoskeleton and focal adhesions.
► Crystal structures of LG3 were determined in apo and Ca2+-bound forms.
► The Ca2+-induced structural changes of LG3 were very restricted, though the actin disassembly activity was dependent on Ca2+ coordination.
► The bound Ca2+ rather than structural rearrangements contributes to antiangiogeneis.
► H4268 on the EF loop was newly identified as a distinctive element for integrin binding and antiangiogenic function.