Engineered annexin A5 variants have impaired cell entry for molecular imaging of apoptosis using pretargeting strategies

Lisette Ungethüm, Heidi Kenis, Gerry A. Nicolaes, Ludovic Autin, Svetla Stoilova-McPhie, Chris P.M. Reutelingsperger

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

Phosphatidylserine (PS) on apoptotic cells is a target for diagnosis and therapy using annexin A5 (anxA5). Pretargeting is a strategy developed to improve signal to background ratio for molecular imaging and to minimize undesired side effects of pharmacological and radiotherapy. Pretargeting relies on accessibility of the target finder on the surface of the target cell. anxA5 binds PS and crystallizes in a two-dimensional network covering the PS-expressing cell surface. Two-dimensional crystallization is the driving force for anxA5 internalization by PS-expressing cells. Here, we report structure/function analysis of anxA5 internalization. Guided by structural bioinformatics including protein-protein docking, we revealed that the amino acids Arg63, Lys70, Lys101, Glu138, Asp139, and Asn160 engage in intermolecular salt bridges within the anxA5 trimer, which is the basic building block of the two-dimensional network. Disruption of the salt bridges by site-directed mutagenesis does not affect PS binding but inhibits trimer formation and cell entry of surface-bound anxA5. The anxA5 variants with impaired internalization are superior molecular imaging agents in pretargeting strategies as compared with wild-type anxA5.

Original languageEnglish (US)
Pages (from-to)1903-1910
Number of pages8
JournalJournal of Biological Chemistry
Volume286
Issue number3
DOIs
StatePublished - Jan 21 2011

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Ungethüm, L., Kenis, H., Nicolaes, G. A., Autin, L., Stoilova-McPhie, S., & Reutelingsperger, C. P. M. (2011). Engineered annexin A5 variants have impaired cell entry for molecular imaging of apoptosis using pretargeting strategies. Journal of Biological Chemistry, 286(3), 1903-1910. https://doi.org/10.1074/jbc.M110.163527