Download MendeleyVariable Zinc Coordination in Endostatin
Hohenester, E., Sasaki, T., Mann, K., Timpl, R.(2000) J Mol Biol 297: 1
- PubMed: 10704302
- DOI: https://doi.org/10.1006/jmbi.2000.3553
- Primary Citation of Related Structures:
1DY0, 1DY1 - PubMed Abstract:
Endostatin is a proteolytic fragment of collagen XVIII that potently inhibits angiogenesis and tumour growth. Human endostatin contains a zinc ion, bound near the N terminus, which was not observed in the original structure of mouse endostatin at pH 5. Controversial data exist on the role of this zinc ion in the anti-tumour activity. We report two new crystal structures of mouse endostatin at pH 8.5 with bound zinc. One crystal form shows a metal ion coordination similar to that in human endostatin (His132, His134, His142, Asp207), but the conformation of the N-terminal segment is different. In the other crystal form, Asp136 replaces His132 as a zinc ligand. Site-directed mutagenesis of zinc-binding residues demonstrates that both coordination geometries occur in solution. The large degree of structural heterogeneity of the zinc-binding site has implications for endostatin function. We conclude that zinc is likely to play a structural rather than a critical functional role in endostatin.
Organizational Affiliation:
Biophysics Section, Blackett Laboratory, Imperial College, London, SW7 2AZ, UK. hohenester@ic.ac.uk
