Structure of Ca2+-bound S100A4 and its interaction with peptides derived from nonmuscle myosin-IIA

Vladimir N. Malashkevich, Kristen M. Varney, Sarah C. Garrett, Paul T. Wilder, David Knight, Thomas H. Charpentier, Udupi A. Ramagopal, Steven C. Almo, David J. Weber, Anne R. Bresnick

Research output: Contribution to journalArticlepeer-review

68 Scopus citations


S100A4, also known as mts1, is a member of the S100 family of Ca 2+-binding proteins that is directly involved in tumor invasion and metastasis via interactions with specific protein targets, including nonmuscle myosin-IIA (MIIA). Human S100A4 binds two Ca2+ ions with the typical EF-hand exhibiting an affinity that is nearly 1 order of magnitude tighter than that of the pseudo-EF-hand. To examine how Ca2+ modifies the overall organization and structure of the protein, we determined the 1.7 Å crystal structure of the human Ca2+-S100A4. Ca2+ binding induces a large reorientation of helix 3 in the typical EF-hand. This reorganization exposes a hydrophobic cleft that is comprised of residues from the hinge region, helix 3, and helix 4, which afford specific target recognition and binding. The Ca2+-dependent conformational change is required for S100A4 to bind peptide sequences derived from the C-terminal portion of the MIIA rod with submicromolar affinity. In addition, the level of binding of Ca2+ to both EF-hands increases by 1 order of magnitude in the presence of MIIA. NMR spectroscopy studies demonstrate that following titration with a MIIA peptide, the largest chemical shift perturbations and exchange broadening effects occur for residues in the hydrophobic pocket of Ca2+-S100A4. Most of these residues are not exposed in apo-S100A4 and explain the Ca2+ dependence of formation of the S100A4-MIIA complex. These studies provide the foundation for understanding S100A4 target recognition and may support the development of reagents that interfere with S100A4 function.

Original languageEnglish (US)
Pages (from-to)5111-5126
Number of pages16
Issue number18
StatePublished - May 6 2008

ASJC Scopus subject areas

  • Biochemistry


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